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drm/dp: move hw_mutex up the call stack

PATCH In review Rob Clark 4 participants 9 messages Feb 25, 2016 – Dec 22, 2016

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Rob Clark

author
#0 lore raw

PATCH 1/2 drm/dp: move hw_mutex up the call stack

1) don't let other threads trying to bang on aux channel interrupt the defer timeout/logic
2) don't let other threads interrupt the i2c over aux logic

Technically, according to people who actually have the DP spec, this should not be required. In practice, it makes some troublesome Dell monitor (and perhaps others) work, so probably a case of "It's compliant if it works with windows" on the hw vendor's part..

v2: rebased to come before DPCD/AUX logging patch for easier backport to stable branches.

Reported-by Dave Wysochanski <[email protected]>

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1274157

Cc [email protected]
Signed-off-by Rob Clark <[email protected]>
---
 drivers/gpu/drm/drm_dp_helper.c | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)
drivers/gpu/drm/drm_dp_helper.c +17 -10
index 7d58f59..df64ed1 100644
@@ -179,7 +179,7 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
 {
 	struct drm_dp_aux_msg msg;
 	unsigned int retry;
-	int err;
+	int err = 0;
 
 	memset(&msg, 0, sizeof(msg));
 	msg.address = offset;

@@ -187,6 +187,8 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
 	msg.buffer = buffer;
 	msg.size = size;
 
+	mutex_lock(&aux->hw_mutex);
+
 	/*
 	 * The specification doesn't give any recommendation on how often to
 	 * retry native transactions. We used to retry 7 times like for

@@ -195,25 +197,24 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
 	 */
 	for (retry = 0; retry < 32; retry++) {
 
-		mutex_lock(&aux->hw_mutex);
 		err = aux->transfer(aux, &msg);
-		mutex_unlock(&aux->hw_mutex);
 		if (err < 0) {
 			if (err == -EBUSY)
 				continue;
 
-			return err;
+			goto unlock;
 		}
 
 
 		switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) {
 		case DP_AUX_NATIVE_REPLY_ACK:
 			if (err < size)
-				return -EPROTO;
-			return err;
+				err = -EPROTO;
+			goto unlock;
 
 		case DP_AUX_NATIVE_REPLY_NACK:
-			return -EIO;
+			err = -EIO;
+			goto unlock;
 
 		case DP_AUX_NATIVE_REPLY_DEFER:
 			usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100);

@@ -222,7 +223,11 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
 	}
 
 	DRM_DEBUG_KMS("too many retries, giving up\n");
-	return -EIO;
+	err = -EIO;
+
+unlock:
+	mutex_unlock(&aux->hw_mutex);
+	return err;
 }
 
 /**

@@ -544,9 +549,7 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 	int max_retries = max(7, drm_dp_i2c_retry_count(msg, dp_aux_i2c_speed_khz));
 
 	for (retry = 0, defer_i2c = 0; retry < (max_retries + defer_i2c); retry++) {
-		mutex_lock(&aux->hw_mutex);
 		ret = aux->transfer(aux, msg);
-		mutex_unlock(&aux->hw_mutex);
 		if (ret < 0) {
 			if (ret == -EBUSY)
 				continue;

@@ -685,6 +688,8 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
 
 	memset(&msg, 0, sizeof(msg));
 
+	mutex_lock(&aux->hw_mutex);
+
 	for (i = 0; i < num; i++) {
 		msg.address = msgs[i].addr;
 		drm_dp_i2c_msg_set_request(&msg, &msgs[i]);

@@ -739,6 +744,8 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
 	msg.size = 0;
 	(void)drm_dp_i2c_do_msg(aux, &msg);
 
+	mutex_unlock(&aux->hw_mutex);
+
 	return err;
 }
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author
#1 lore raw

PATCH 2/2 drm/dp: add DPCD/AUX logging

Add a new drm_debug bit for turning on DPCD logging, to aid debugging with troublesome monitors.

v2: don't try to hexdump the universe if driver returns -errno, and change the "too many retries" traces to DRM_ERROR()
v3: rename to more generic "AUX" instead of DP specific DPCD, add DP_AUX_I2C_WRITE_STATUS_UPDATE

Signed-off-by Rob Clark <[email protected]>
---
 drivers/gpu/drm/drm_dp_helper.c | 62 +++++++++++++++++++++++++++++++++--------
 include/drm/drmP.h              |  8 +++++-
 2 files changed, 58 insertions(+), 12 deletions(-)
drivers/gpu/drm/drm_dp_helper.c +51 -11
index df64ed1..3ef35fd 100644
@@ -160,6 +160,45 @@ int drm_dp_bw_code_to_link_rate(u8 link_bw)
 }
 EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate);
 
+static ssize_t aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
+{
+	ssize_t ret;
+
+	DRM_DEBUG_AUX("%s: req=0x%02x, address=0x%05x, size=%zu\n", aux->name,
+			msg->request, msg->address, msg->size);
+
+	if (unlikely(drm_debug & DRM_UT_AUX)) {
+		switch (msg->request & ~DP_AUX_I2C_MOT) {
+		case DP_AUX_NATIVE_WRITE:
+		case DP_AUX_I2C_WRITE:
+		case DP_AUX_I2C_WRITE_STATUS_UPDATE:
+			print_hex_dump(KERN_DEBUG, "DPCD: ", DUMP_PREFIX_OFFSET,
+					16, 1, msg->buffer, msg->size, false);
+			break;
+		default:
+			break;
+		}
+	}
+
+	ret = aux->transfer(aux, msg);
+
+	DRM_DEBUG_AUX("%s: reply=0x%02x, size=%zd\n", aux->name, msg->reply, ret);
+
+	if (unlikely(drm_debug & DRM_UT_AUX) && (ret > 0)) {
+		switch (msg->request & ~DP_AUX_I2C_MOT) {
+		case DP_AUX_NATIVE_READ:
+		case DP_AUX_I2C_READ:
+			print_hex_dump(KERN_DEBUG, "DPCD: ", DUMP_PREFIX_OFFSET,
+					16, 1, msg->buffer, ret, false);
+			break;
+		default:
+			break;
+		}
+	}
+
+	return ret;
+}
+
 #define AUX_RETRY_INTERVAL 500 /* us */
 
 /**

@@ -197,7 +236,7 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
 	 */
 	for (retry = 0; retry < 32; retry++) {
 
-		err = aux->transfer(aux, &msg);
+		err = aux_transfer(aux, &msg);
 		if (err < 0) {
 			if (err == -EBUSY)
 				continue;

@@ -205,7 +244,6 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
 			goto unlock;
 		}
 
-
 		switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) {
 		case DP_AUX_NATIVE_REPLY_ACK:
 			if (err < size)

@@ -213,16 +251,18 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
 			goto unlock;
 
 		case DP_AUX_NATIVE_REPLY_NACK:
+			DRM_DEBUG_AUX("native nack (result=%d, size=%zu)\n", err, msg.size);
 			err = -EIO;
 			goto unlock;
 
 		case DP_AUX_NATIVE_REPLY_DEFER:
+			DRM_DEBUG_AUX("native defer\n");
 			usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100);
 			break;
 		}
 	}
 
-	DRM_DEBUG_KMS("too many retries, giving up\n");
+	DRM_ERROR("DPCD: too many retries, giving up!\n");
 	err = -EIO;
 
 unlock:

@@ -549,12 +589,12 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 	int max_retries = max(7, drm_dp_i2c_retry_count(msg, dp_aux_i2c_speed_khz));
 
 	for (retry = 0, defer_i2c = 0; retry < (max_retries + defer_i2c); retry++) {
-		ret = aux->transfer(aux, msg);
+		ret = aux_transfer(aux, msg);
 		if (ret < 0) {
 			if (ret == -EBUSY)
 				continue;
 
-			DRM_DEBUG_KMS("transaction failed: %d\n", ret);
+			DRM_DEBUG_AUX("transaction failed: %d\n", ret);
 			return ret;
 		}
 

@@ -568,11 +608,11 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 			break;
 
 		case DP_AUX_NATIVE_REPLY_NACK:
-			DRM_DEBUG_KMS("native nack (result=%d, size=%zu)\n", ret, msg->size);
+			DRM_DEBUG_AUX("native nack (result=%d, size=%zu)\n", ret, msg->size);
 			return -EREMOTEIO;
 
 		case DP_AUX_NATIVE_REPLY_DEFER:
-			DRM_DEBUG_KMS("native defer\n");
+			DRM_DEBUG_AUX("native defer\n");
 			/*
 			 * We could check for I2C bit rate capabilities and if
 			 * available adjust this interval. We could also be

@@ -601,12 +641,12 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 			return ret;
 
 		case DP_AUX_I2C_REPLY_NACK:
-			DRM_DEBUG_KMS("I2C nack (result=%d, size=%zu\n", ret, msg->size);
+			DRM_DEBUG_AUX("I2C nack (result=%d, size=%zu)\n", ret, msg->size);
 			aux->i2c_nack_count++;
 			return -EREMOTEIO;
 
 		case DP_AUX_I2C_REPLY_DEFER:
-			DRM_DEBUG_KMS("I2C defer\n");
+			DRM_DEBUG_AUX("I2C defer\n");
 			/* DP Compliance Test 4.2.2.5 Requirement:
 			 * Must have at least 7 retries for I2C defers on the
 			 * transaction to pass this test

@@ -625,7 +665,7 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 		}
 	}
 
-	DRM_DEBUG_KMS("too many retries, giving up\n");
+	DRM_ERROR("I2C: too many retries, giving up\n");
 	return -EREMOTEIO;
 }
 

@@ -653,7 +693,7 @@ static int drm_dp_i2c_drain_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *o
 			return err == 0 ? -EPROTO : err;
 
 		if (err < msg.size && err < ret) {
-			DRM_DEBUG_KMS("Partial I2C reply: requested %zu bytes got %d bytes\n",
+			DRM_DEBUG_AUX("Partial I2C reply: requested %zu bytes got %d bytes\n",
 				      msg.size, err);
 			ret = err;
 		}
include/drm/drmP.h +7 -1
index 3c8422c..cc524b5 100644
@@ -117,7 +117,7 @@ struct dma_buf_attachment;
  * drm.debug=0x2 will enable DRIVER messages
  * drm.debug=0x3 will enable CORE and DRIVER messages
  * ...
- * drm.debug=0x3f will enable all messages
+ * drm.debug=0x7f will enable all messages
  *
  * An interesting feature is that it's possible to enable verbose logging at
  * run-time by echoing the debug value in its sysfs node:

@@ -129,6 +129,7 @@ struct dma_buf_attachment;
 #define DRM_UT_PRIME		0x08
 #define DRM_UT_ATOMIC		0x10
 #define DRM_UT_VBL		0x20
+#define DRM_UT_AUX		0x40
 
 extern __printf(2, 3)
 void drm_ut_debug_printk(const char *function_name,

@@ -226,6 +227,11 @@ void drm_err(const char *format, ...);
 		if (unlikely(drm_debug & DRM_UT_VBL))			\
 			drm_ut_debug_printk(__func__, fmt, ##args);	\
 	} while (0)
+#define DRM_DEBUG_AUX(fmt, args...)					\
+	do {								\
+		if (unlikely(drm_debug & DRM_UT_AUX))			\
+			drm_ut_debug_printk(__func__, fmt, ##args);	\
+	} while (0)
 
 /*@}*/
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#2 lore raw

Re: [PATCH 2/2] drm/dp: add DPCD/AUX logging

Quoted 19 lines · Rob Clark

Add a new drm_debug bit for turning on DPCD logging, to aid debugging with troublesome monitors.

v2: don't try to hexdump the universe if driver returns -errno, and change the "too many retries" traces to DRM_ERROR()
v3: rename to more generic "AUX" instead of DP specific DPCD, add DP_AUX_I2C_WRITE_STATUS_UPDATE

Signed-off-by Rob Clark <[email protected]>
---
 drivers/gpu/drm/drm_dp_helper.c | 62 +++++++++++++++++++++++++++++++++--------
 include/drm/drmP.h              |  8 +++++-
 2 files changed, 58 insertions(+), 12 deletions(-)
drivers/gpu/drm/drm_dp_helper.c +0 -0
index df64ed1..3ef35fd 100644

drivers/gpu/drm/drm_dp_helper.c int drm_dp_bw_code_to_link_rate(u8 link_bw) · line 168

Quoted 9 lines
drivers/gpu/drm/drm_dp_helper.c +6 -0
@@ -160,6 +160,45 @@ int drm_dp_bw_code_to_link_rate(u8 link_bw)
 }
 EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate);
 
+static ssize_t aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
+{
+	ssize_t ret;
+
+	DRM_DEBUG_AUX("%s: req=0x%02x, address=0x%05x, size=%zu\n", aux->name,
+			msg->request, msg->address, msg->size);

Bunch of stuff doesn't seem to be indented quite right in this patch. This being one of them.

drivers/gpu/drm/drm_dp_helper.c int drm_dp_bw_code_to_link_rate(u8 link_bw) · line 176

Quoted 8 lines
drivers/gpu/drm/drm_dp_helper.c +8 -0
+
+	if (unlikely(drm_debug & DRM_UT_AUX)) {
+		switch (msg->request & ~DP_AUX_I2C_MOT) {
+		case DP_AUX_NATIVE_WRITE:
+		case DP_AUX_I2C_WRITE:
+		case DP_AUX_I2C_WRITE_STATUS_UPDATE:
+			print_hex_dump(KERN_DEBUG, "DPCD: ", DUMP_PREFIX_OFFSET,
+					16, 1, msg->buffer, msg->size, false);

That shouldn't say "DPCD", at least for i2c.

Quoted 6 lines
drivers/gpu/drm/drm_dp_helper.c +6 -0
+			break;
+		default:
+			break;
+		}
+	}
+

drivers/gpu/drm/drm_dp_helper.c int drm_dp_bw_code_to_link_rate(u8 link_bw) · line 192

Quoted 10 lines
drivers/gpu/drm/drm_dp_helper.c +10 -0
+	ret = aux->transfer(aux, msg);
+
+	DRM_DEBUG_AUX("%s: reply=0x%02x, size=%zd\n", aux->name, msg->reply, ret);
+
+	if (unlikely(drm_debug & DRM_UT_AUX) && (ret > 0)) {
+		switch (msg->request & ~DP_AUX_I2C_MOT) {
+		case DP_AUX_NATIVE_READ:
+		case DP_AUX_I2C_READ:
+			print_hex_dump(KERN_DEBUG, "DPCD: ", DUMP_PREFIX_OFFSET,
+					16, 1, msg->buffer, ret, false);

ditto

Otherwise looks all right.

Quoted 146 lines
drivers/gpu/drm/drm_dp_helper.c +21 -11
+			break;
+		default:
+			break;
+		}
+	}
+
+	return ret;
+}
+
 #define AUX_RETRY_INTERVAL 500 /* us */
 
 /**

@@ -197,7 +236,7 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
 	 */
 	for (retry = 0; retry < 32; retry++) {
 
-		err = aux->transfer(aux, &msg);
+		err = aux_transfer(aux, &msg);
 		if (err < 0) {
 			if (err == -EBUSY)
 				continue;

@@ -205,7 +244,6 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
 			goto unlock;
 		}
 
-
 		switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) {
 		case DP_AUX_NATIVE_REPLY_ACK:
 			if (err < size)

@@ -213,16 +251,18 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
 			goto unlock;
 
 		case DP_AUX_NATIVE_REPLY_NACK:
+			DRM_DEBUG_AUX("native nack (result=%d, size=%zu)\n", err, msg.size);
 			err = -EIO;
 			goto unlock;
 
 		case DP_AUX_NATIVE_REPLY_DEFER:
+			DRM_DEBUG_AUX("native defer\n");
 			usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100);
 			break;
 		}
 	}
 
-	DRM_DEBUG_KMS("too many retries, giving up\n");
+	DRM_ERROR("DPCD: too many retries, giving up!\n");
 	err = -EIO;
 
 unlock:

@@ -549,12 +589,12 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 	int max_retries = max(7, drm_dp_i2c_retry_count(msg, dp_aux_i2c_speed_khz));
 
 	for (retry = 0, defer_i2c = 0; retry < (max_retries + defer_i2c); retry++) {
-		ret = aux->transfer(aux, msg);
+		ret = aux_transfer(aux, msg);
 		if (ret < 0) {
 			if (ret == -EBUSY)
 				continue;
 
-			DRM_DEBUG_KMS("transaction failed: %d\n", ret);
+			DRM_DEBUG_AUX("transaction failed: %d\n", ret);
 			return ret;
 		}
 

@@ -568,11 +608,11 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 			break;
 
 		case DP_AUX_NATIVE_REPLY_NACK:
-			DRM_DEBUG_KMS("native nack (result=%d, size=%zu)\n", ret, msg->size);
+			DRM_DEBUG_AUX("native nack (result=%d, size=%zu)\n", ret, msg->size);
 			return -EREMOTEIO;
 
 		case DP_AUX_NATIVE_REPLY_DEFER:
-			DRM_DEBUG_KMS("native defer\n");
+			DRM_DEBUG_AUX("native defer\n");
 			/*
 			 * We could check for I2C bit rate capabilities and if
 			 * available adjust this interval. We could also be

@@ -601,12 +641,12 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 			return ret;
 
 		case DP_AUX_I2C_REPLY_NACK:
-			DRM_DEBUG_KMS("I2C nack (result=%d, size=%zu\n", ret, msg->size);
+			DRM_DEBUG_AUX("I2C nack (result=%d, size=%zu)\n", ret, msg->size);
 			aux->i2c_nack_count++;
 			return -EREMOTEIO;
 
 		case DP_AUX_I2C_REPLY_DEFER:
-			DRM_DEBUG_KMS("I2C defer\n");
+			DRM_DEBUG_AUX("I2C defer\n");
 			/* DP Compliance Test 4.2.2.5 Requirement:
 			 * Must have at least 7 retries for I2C defers on the
 			 * transaction to pass this test

@@ -625,7 +665,7 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 		}
 	}
 
-	DRM_DEBUG_KMS("too many retries, giving up\n");
+	DRM_ERROR("I2C: too many retries, giving up\n");
 	return -EREMOTEIO;
 }
 

@@ -653,7 +693,7 @@ static int drm_dp_i2c_drain_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *o
 			return err == 0 ? -EPROTO : err;
 
 		if (err < msg.size && err < ret) {
-			DRM_DEBUG_KMS("Partial I2C reply: requested %zu bytes got %d bytes\n",
+			DRM_DEBUG_AUX("Partial I2C reply: requested %zu bytes got %d bytes\n",
 				      msg.size, err);
 			ret = err;
 		}
include/drm/drmP.h +7 -1
index 3c8422c..cc524b5 100644
@@ -117,7 +117,7 @@ struct dma_buf_attachment;
  * drm.debug=0x2 will enable DRIVER messages
  * drm.debug=0x3 will enable CORE and DRIVER messages
  * ...
- * drm.debug=0x3f will enable all messages
+ * drm.debug=0x7f will enable all messages
  *
  * An interesting feature is that it's possible to enable verbose logging at
  * run-time by echoing the debug value in its sysfs node:

@@ -129,6 +129,7 @@ struct dma_buf_attachment;
 #define DRM_UT_PRIME		0x08
 #define DRM_UT_ATOMIC		0x10
 #define DRM_UT_VBL		0x20
+#define DRM_UT_AUX		0x40
 
 extern __printf(2, 3)
 void drm_ut_debug_printk(const char *function_name,

@@ -226,6 +227,11 @@ void drm_err(const char *format, ...);
 		if (unlikely(drm_debug & DRM_UT_VBL))			\
 			drm_ut_debug_printk(__func__, fmt, ##args);	\
 	} while (0)
+#define DRM_DEBUG_AUX(fmt, args...)					\
+	do {								\
+		if (unlikely(drm_debug & DRM_UT_AUX))			\
+			drm_ut_debug_printk(__func__, fmt, ##args);	\
+	} while (0)
 
 /*@}*/
Signature · 1 line
2.5.0
Signature · 6 lines
Ville Syrjälä
Intel OTC
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Acked-by on v1 2/2
#3 lore raw

Re: [PATCH 2/2] drm/dp: add DPCD/AUX logging

In reply to Rob Clark
Quoted 9 lines · Rob Clark

Add a new drm_debug bit for turning on DPCD logging, to aid debugging with troublesome monitors.

v2: don't try to hexdump the universe if driver returns -errno, and change the "too many retries" traces to DRM_ERROR()
v3: rename to more generic "AUX" instead of DP specific DPCD, add DP_AUX_I2C_WRITE_STATUS_UPDATE

Signed-off-by Rob Clark <[email protected]>

I used the rebased version of this after Ville pointed me to it for remote debugging some odd adaptor behavior. It'd be quite useful imo, so:

Acked-by Imre Deak <[email protected]>
Quoted 184 lines

---
 drivers/gpu/drm/drm_dp_helper.c | 62 +++++++++++++++++++++++++++++++++-------- include/drm/drmP.h              |  8 +++++-

 2 files changed, 58 insertions(+), 12 deletions(-)
drivers/gpu/drm/drm_dp_helper.c +0 -0
index df64ed1..3ef35fd 100644
@@ -160,6 +160,45 @@ int drm_dp_bw_code_to_link_rate(u8 link_bw)
  }
  EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate);

drivers/gpu/drm/drm_dp_helper.c +39 -0
+static ssize_t aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
+{
+	ssize_t ret;
+
+	DRM_DEBUG_AUX("%s: req=0x%02x, address=0x%05x, size=%zu\n", aux->name,
+			msg->request, msg->address, msg->size);
+
+	if (unlikely(drm_debug & DRM_UT_AUX)) {
+		switch (msg->request & ~DP_AUX_I2C_MOT) {
+		case DP_AUX_NATIVE_WRITE:
+		case DP_AUX_I2C_WRITE:
+		case DP_AUX_I2C_WRITE_STATUS_UPDATE:
+			print_hex_dump(KERN_DEBUG, "DPCD: ", DUMP_PREFIX_OFFSET,
+					16, 1, msg->buffer, msg->size, false);
+			break;
+		default:
+			break;
+		}
+	}
+
+	ret = aux->transfer(aux, msg);
+
+	DRM_DEBUG_AUX("%s: reply=0x%02x, size=%zd\n", aux->name, msg->reply, ret);
+
+	if (unlikely(drm_debug & DRM_UT_AUX) && (ret > 0)) {
+		switch (msg->request & ~DP_AUX_I2C_MOT) {
+		case DP_AUX_NATIVE_READ:
+		case DP_AUX_I2C_READ:
+			print_hex_dump(KERN_DEBUG, "DPCD: ", DUMP_PREFIX_OFFSET,
+					16, 1, msg->buffer, ret, false);
+			break;
+		default:
+			break;
+		}
+	}
+
+	return ret;
+}
+

 #define AUX_RETRY_INTERVAL 500 /* us */

 /**

drivers/gpu/drm/drm_dp_helper.c +0 -0
@@ -197,7 +236,7 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
  	 */
  	for (retry = 0; retry < 32; retry++) {

drivers/gpu/drm/drm_dp_helper.c +1 -1
-		err = aux->transfer(aux, &msg);
+		err = aux_transfer(aux, &msg);

  if (err < 0) {
  if (err == -EBUSY)
  continue;

drivers/gpu/drm/drm_dp_helper.c +0 -0
@@ -205,7 +244,6 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
  			goto unlock;
  		}


-
  switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) { case DP_AUX_NATIVE_REPLY_ACK:
  if (err < size)

drivers/gpu/drm/drm_dp_helper.c +0 -0
@@ -213,16 +251,18 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
  			goto unlock;


  case DP_AUX_NATIVE_REPLY_NACK:

drivers/gpu/drm/drm_dp_helper.c +1 -0
+			DRM_DEBUG_AUX("native nack (result=%d, size=%zu)\n", err, msg.size);

  err = -EIO;
  goto unlock;

  case DP_AUX_NATIVE_REPLY_DEFER:

drivers/gpu/drm/drm_dp_helper.c +1 -0
+			DRM_DEBUG_AUX("native defer\n");

  usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100); break;
  }
  }

drivers/gpu/drm/drm_dp_helper.c +1 -1
-	DRM_DEBUG_KMS("too many retries, giving up\n");
+	DRM_ERROR("DPCD: too many retries, giving up!\n");

  err = -EIO;

 unlock:

drivers/gpu/drm/drm_dp_helper.c +0 -0
@@ -549,12 +589,12 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
  	int max_retries = max(7, drm_dp_i2c_retry_count(msg, dp_aux_i2c_speed_khz));


  for (retry = 0, defer_i2c = 0; retry < (max_retries + defer_i2c); retry++) {

drivers/gpu/drm/drm_dp_helper.c +1 -1
-		ret = aux->transfer(aux, msg);
+		ret = aux_transfer(aux, msg);

  if (ret < 0) {
  if (ret == -EBUSY)
  continue;

drivers/gpu/drm/drm_dp_helper.c +1 -1
-			DRM_DEBUG_KMS("transaction failed: %d\n", ret);
+			DRM_DEBUG_AUX("transaction failed: %d\n", ret);

  return ret;
  }

drivers/gpu/drm/drm_dp_helper.c +0 -0
@@ -568,11 +608,11 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
  			break;


  case DP_AUX_NATIVE_REPLY_NACK:

drivers/gpu/drm/drm_dp_helper.c +1 -1
-			DRM_DEBUG_KMS("native nack (result=%d, size=%zu)\n", ret, msg->size);
+			DRM_DEBUG_AUX("native nack (result=%d, size=%zu)\n", ret, msg->size);

  return -EREMOTEIO;

  case DP_AUX_NATIVE_REPLY_DEFER:

drivers/gpu/drm/drm_dp_helper.c +1 -1
-			DRM_DEBUG_KMS("native defer\n");
+			DRM_DEBUG_AUX("native defer\n");

  /*
   * We could check for I2C bit rate capabilities and if
   * available adjust this interval. We could also be

drivers/gpu/drm/drm_dp_helper.c +0 -0
@@ -601,12 +641,12 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
  			return ret;


  case DP_AUX_I2C_REPLY_NACK:

drivers/gpu/drm/drm_dp_helper.c +1 -1
-			DRM_DEBUG_KMS("I2C nack (result=%d, size=%zu\n", ret, msg->size);
+			DRM_DEBUG_AUX("I2C nack (result=%d, size=%zu)\n", ret, msg->size);

  aux->i2c_nack_count++;
  return -EREMOTEIO;

  case DP_AUX_I2C_REPLY_DEFER:

drivers/gpu/drm/drm_dp_helper.c +1 -1
-			DRM_DEBUG_KMS("I2C defer\n");
+			DRM_DEBUG_AUX("I2C defer\n");

  /* DP Compliance Test 4.2.2.5 Requirement:
   * Must have at least 7 retries for I2C defers on the
   * transaction to pass this test

drivers/gpu/drm/drm_dp_helper.c +0 -0
@@ -625,7 +665,7 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
  		}
  	}

drivers/gpu/drm/drm_dp_helper.c +1 -1
-	DRM_DEBUG_KMS("too many retries, giving up\n");
+	DRM_ERROR("I2C: too many retries, giving up\n");

  return -EREMOTEIO;
 }

drivers/gpu/drm/drm_dp_helper.c +0 -0
@@ -653,7 +693,7 @@ static int drm_dp_i2c_drain_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *o
  			return err == 0 ? -EPROTO : err;


  if (err < msg.size && err < ret) {

drivers/gpu/drm/drm_dp_helper.c +1 -1
-			DRM_DEBUG_KMS("Partial I2C reply: requested %zu bytes got %d bytes\n",
+			DRM_DEBUG_AUX("Partial I2C reply: requested %zu bytes got %d bytes\n",

        msg.size, err); ret = err;
  }

include/drm/drmP.h +2 -1
index 3c8422c..cc524b5 100644
@@ -117,7 +117,7 @@ struct dma_buf_attachment;
   * drm.debug=0x2 will enable DRIVER messages
   * drm.debug=0x3 will enable CORE and DRIVER messages
   * ...
- * drm.debug=0x3f will enable all messages
+ * drm.debug=0x7f will enable all messages
   *
   * An interesting feature is that it's possible to enable verbose logging at
   * run-time by echoing the debug value in its sysfs node:

@@ -129,6 +129,7 @@ struct dma_buf_attachment;
  #define DRM_UT_PRIME		0x08
  #define DRM_UT_ATOMIC		0x10
  #define DRM_UT_VBL		0x20
+#define DRM_UT_AUX		0x40


 extern __printf(2, 3)
 void drm_ut_debug_printk(const char *function_name,

include/drm/drmP.h +5 -0
@@ -226,6 +227,11 @@ void drm_err(const char *format, ...);
  		if (unlikely(drm_debug & DRM_UT_VBL))			\
  			drm_ut_debug_printk(__func__, fmt, ##args);	\
  	} while (0)
+#define DRM_DEBUG_AUX(fmt, args...)					\
+	do {								\
+		if (unlikely(drm_debug & DRM_UT_AUX))			\
+			drm_ut_debug_printk(__func__, fmt, ##args);	\
+	} while (0)
Quoted 3 lines


 /*@}*/

_______________________________________________
dri-devel mailing list
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https://lists.freedesktop.org/mailman/listinfo/dri-devel

author
#4 lore raw

Re: [PATCH 2/2] drm/dp: add DPCD/AUX logging

Quoted 9 lines · Imre Deak
Quoted 8 lines · Rob Clark

Add a new drm_debug bit for turning on DPCD logging, to aid debugging with troublesome monitors.

v2: don't try to hexdump the universe if driver returns -errno, and change the "too many retries" traces to DRM_ERROR()
v3: rename to more generic "AUX" instead of DP specific DPCD, add DP_AUX_I2C_WRITE_STATUS_UPDATE

Quoted 5 lines
Quoted 1 line
Signed-off-by Rob Clark <[email protected]>

I used the rebased version of this after Ville pointed me to it for remote debugging some odd adaptor behavior. It'd be quite useful imo, so:

Acked-by Imre Deak <[email protected]>

tbh I completely forgot about this patch.. mind posting the rebased version (or push to a git tree somewhere)? IIRC there were just some minor cosmetic things to fix up, probably worth doing that before I forget about it again..

BR,
-R

Quoted 186 lines
Quoted 186 lines
---
 drivers/gpu/drm/drm_dp_helper.c | 62 +++++++++++++++++++++++++++++++++--------
 include/drm/drmP.h              |  8 +++++-
 2 files changed, 58 insertions(+), 12 deletions(-)
drivers/gpu/drm/drm_dp_helper.c +51 -11
index df64ed1..3ef35fd 100644
@@ -160,6 +160,45 @@ int drm_dp_bw_code_to_link_rate(u8 link_bw)
 }
 EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate);
 
+static ssize_t aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
+{
+     ssize_t ret;
+
+     DRM_DEBUG_AUX("%s: req=0x%02x, address=0x%05x, size=%zu\n", aux->name,
+                     msg->request, msg->address, msg->size);
+
+     if (unlikely(drm_debug & DRM_UT_AUX)) {
+             switch (msg->request & ~DP_AUX_I2C_MOT) {
+             case DP_AUX_NATIVE_WRITE:
+             case DP_AUX_I2C_WRITE:
+             case DP_AUX_I2C_WRITE_STATUS_UPDATE:
+                     print_hex_dump(KERN_DEBUG, "DPCD: ", DUMP_PREFIX_OFFSET,
+                                     16, 1, msg->buffer, msg->size, false);
+                     break;
+             default:
+                     break;
+             }
+     }
+
+     ret = aux->transfer(aux, msg);
+
+     DRM_DEBUG_AUX("%s: reply=0x%02x, size=%zd\n", aux->name, msg->reply, ret);
+
+     if (unlikely(drm_debug & DRM_UT_AUX) && (ret > 0)) {
+             switch (msg->request & ~DP_AUX_I2C_MOT) {
+             case DP_AUX_NATIVE_READ:
+             case DP_AUX_I2C_READ:
+                     print_hex_dump(KERN_DEBUG, "DPCD: ", DUMP_PREFIX_OFFSET,
+                                     16, 1, msg->buffer, ret, false);
+                     break;
+             default:
+                     break;
+             }
+     }
+
+     return ret;
+}
+
 #define AUX_RETRY_INTERVAL 500 /* us */
 
 /**

@@ -197,7 +236,7 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
       */
      for (retry = 0; retry < 32; retry++) {
 
-             err = aux->transfer(aux, &msg);
+             err = aux_transfer(aux, &msg);
              if (err < 0) {
                      if (err == -EBUSY)
                              continue;

@@ -205,7 +244,6 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
                      goto unlock;
              }
 
-
              switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) {
              case DP_AUX_NATIVE_REPLY_ACK:
                      if (err < size)

@@ -213,16 +251,18 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
                      goto unlock;
 
              case DP_AUX_NATIVE_REPLY_NACK:
+                     DRM_DEBUG_AUX("native nack (result=%d, size=%zu)\n", err, msg.size);
                      err = -EIO;
                      goto unlock;
 
              case DP_AUX_NATIVE_REPLY_DEFER:
+                     DRM_DEBUG_AUX("native defer\n");
                      usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100);
                      break;
              }
      }
 
-     DRM_DEBUG_KMS("too many retries, giving up\n");
+     DRM_ERROR("DPCD: too many retries, giving up!\n");
      err = -EIO;
 
 unlock:

@@ -549,12 +589,12 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
      int max_retries = max(7, drm_dp_i2c_retry_count(msg, dp_aux_i2c_speed_khz));
 
      for (retry = 0, defer_i2c = 0; retry < (max_retries + defer_i2c); retry++) {
-             ret = aux->transfer(aux, msg);
+             ret = aux_transfer(aux, msg);
              if (ret < 0) {
                      if (ret == -EBUSY)
                              continue;
 
-                     DRM_DEBUG_KMS("transaction failed: %d\n", ret);
+                     DRM_DEBUG_AUX("transaction failed: %d\n", ret);
                      return ret;
              }
 

@@ -568,11 +608,11 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
                      break;
 
              case DP_AUX_NATIVE_REPLY_NACK:
-                     DRM_DEBUG_KMS("native nack (result=%d, size=%zu)\n", ret, msg->size);
+                     DRM_DEBUG_AUX("native nack (result=%d, size=%zu)\n", ret, msg->size);
                      return -EREMOTEIO;
 
              case DP_AUX_NATIVE_REPLY_DEFER:
-                     DRM_DEBUG_KMS("native defer\n");
+                     DRM_DEBUG_AUX("native defer\n");
                      /*
                       * We could check for I2C bit rate capabilities and if
                       * available adjust this interval. We could also be

@@ -601,12 +641,12 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
                      return ret;
 
              case DP_AUX_I2C_REPLY_NACK:
-                     DRM_DEBUG_KMS("I2C nack (result=%d, size=%zu\n", ret, msg->size);
+                     DRM_DEBUG_AUX("I2C nack (result=%d, size=%zu)\n", ret, msg->size);
                      aux->i2c_nack_count++;
                      return -EREMOTEIO;
 
              case DP_AUX_I2C_REPLY_DEFER:
-                     DRM_DEBUG_KMS("I2C defer\n");
+                     DRM_DEBUG_AUX("I2C defer\n");
                      /* DP Compliance Test 4.2.2.5 Requirement:
                       * Must have at least 7 retries for I2C defers on the
                       * transaction to pass this test

@@ -625,7 +665,7 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
              }
      }
 
-     DRM_DEBUG_KMS("too many retries, giving up\n");
+     DRM_ERROR("I2C: too many retries, giving up\n");
      return -EREMOTEIO;
 }
 

@@ -653,7 +693,7 @@ static int drm_dp_i2c_drain_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *o
                      return err == 0 ? -EPROTO : err;
 
              if (err < msg.size && err < ret) {
-                     DRM_DEBUG_KMS("Partial I2C reply: requested %zu bytes got %d bytes\n",
+                     DRM_DEBUG_AUX("Partial I2C reply: requested %zu bytes got %d bytes\n",
                                    msg.size, err);
                      ret = err;
              }
include/drm/drmP.h +7 -1
index 3c8422c..cc524b5 100644
@@ -117,7 +117,7 @@ struct dma_buf_attachment;
  * drm.debug=0x2 will enable DRIVER messages
  * drm.debug=0x3 will enable CORE and DRIVER messages
  * ...
- * drm.debug=0x3f will enable all messages
+ * drm.debug=0x7f will enable all messages
  *
  * An interesting feature is that it's possible to enable verbose logging at
  * run-time by echoing the debug value in its sysfs node:

@@ -129,6 +129,7 @@ struct dma_buf_attachment;
 #define DRM_UT_PRIME         0x08
 #define DRM_UT_ATOMIC                0x10
 #define DRM_UT_VBL           0x20
+#define DRM_UT_AUX           0x40
 
 extern __printf(2, 3)
 void drm_ut_debug_printk(const char *function_name,

@@ -226,6 +227,11 @@ void drm_err(const char *format, ...);
              if (unlikely(drm_debug & DRM_UT_VBL))                   \
                      drm_ut_debug_printk(__func__, fmt, ##args);     \
      } while (0)
+#define DRM_DEBUG_AUX(fmt, args...)                                  \
+     do {                                                            \
+             if (unlikely(drm_debug & DRM_UT_AUX))                   \
+                     drm_ut_debug_printk(__func__, fmt, ##args);     \
+     } while (0)
Quoted 2 lines

include/drm/drmP.h void drm_err(const char *format, ...); · line 237

Quoted 2 lines
include/drm/drmP.h +0 -0
 /*@}*/

_______________________________________________
dri-devel mailing list
[email protected]
https://lists.freedesktop.org/mailman/listinfo/dri-devel

#5 lore raw

Re: [PATCH 2/2] drm/dp: add DPCD/AUX logging

Quoted 12 lines · Rob Clark
Quoted 11 lines · Imre Deak
Quoted 9 lines · Rob Clark

Add a new drm_debug bit for turning on DPCD logging, to aid debugging with troublesome monitors.

v2: don't try to hexdump the universe if driver returns -errno, and change the "too many retries" traces to DRM_ERROR()
v3: rename to more generic "AUX" instead of DP specific DPCD, add DP_AUX_I2C_WRITE_STATUS_UPDATE

Signed-off-by Rob Clark <[email protected]>
Quoted 8 lines
Quoted 3 lines

I used the rebased version of this after Ville pointed me to it for remote debugging some odd adaptor behavior. It'd be quite useful imo, so:

Acked-by Imre Deak <[email protected]>

tbh I completely forgot about this patch.. mind posting the rebased version (or push to a git tree somewhere)? IIRC there were just some minor cosmetic things to fix up, probably worth doing that before I forget about it again..

There's patches for dynamic debugging floating around, I think that'd be the more interesting approach than adding ever more magic bits that no one understands. But besides that this makes sense.
-Daniel

Quoted 197 lines

BR,
-R

Quoted 186 lines
Quoted 186 lines
---
 drivers/gpu/drm/drm_dp_helper.c | 62 +++++++++++++++++++++++++++++++++--------
 include/drm/drmP.h              |  8 +++++-
 2 files changed, 58 insertions(+), 12 deletions(-)
drivers/gpu/drm/drm_dp_helper.c +51 -11
index df64ed1..3ef35fd 100644
@@ -160,6 +160,45 @@ int drm_dp_bw_code_to_link_rate(u8 link_bw)
 }
 EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate);
 
+static ssize_t aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
+{
+     ssize_t ret;
+
+     DRM_DEBUG_AUX("%s: req=0x%02x, address=0x%05x, size=%zu\n", aux->name,
+                     msg->request, msg->address, msg->size);
+
+     if (unlikely(drm_debug & DRM_UT_AUX)) {
+             switch (msg->request & ~DP_AUX_I2C_MOT) {
+             case DP_AUX_NATIVE_WRITE:
+             case DP_AUX_I2C_WRITE:
+             case DP_AUX_I2C_WRITE_STATUS_UPDATE:
+                     print_hex_dump(KERN_DEBUG, "DPCD: ", DUMP_PREFIX_OFFSET,
+                                     16, 1, msg->buffer, msg->size, false);
+                     break;
+             default:
+                     break;
+             }
+     }
+
+     ret = aux->transfer(aux, msg);
+
+     DRM_DEBUG_AUX("%s: reply=0x%02x, size=%zd\n", aux->name, msg->reply, ret);
+
+     if (unlikely(drm_debug & DRM_UT_AUX) && (ret > 0)) {
+             switch (msg->request & ~DP_AUX_I2C_MOT) {
+             case DP_AUX_NATIVE_READ:
+             case DP_AUX_I2C_READ:
+                     print_hex_dump(KERN_DEBUG, "DPCD: ", DUMP_PREFIX_OFFSET,
+                                     16, 1, msg->buffer, ret, false);
+                     break;
+             default:
+                     break;
+             }
+     }
+
+     return ret;
+}
+
 #define AUX_RETRY_INTERVAL 500 /* us */
 
 /**

@@ -197,7 +236,7 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
       */
      for (retry = 0; retry < 32; retry++) {
 
-             err = aux->transfer(aux, &msg);
+             err = aux_transfer(aux, &msg);
              if (err < 0) {
                      if (err == -EBUSY)
                              continue;

@@ -205,7 +244,6 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
                      goto unlock;
              }
 
-
              switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) {
              case DP_AUX_NATIVE_REPLY_ACK:
                      if (err < size)

@@ -213,16 +251,18 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
                      goto unlock;
 
              case DP_AUX_NATIVE_REPLY_NACK:
+                     DRM_DEBUG_AUX("native nack (result=%d, size=%zu)\n", err, msg.size);
                      err = -EIO;
                      goto unlock;
 
              case DP_AUX_NATIVE_REPLY_DEFER:
+                     DRM_DEBUG_AUX("native defer\n");
                      usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100);
                      break;
              }
      }
 
-     DRM_DEBUG_KMS("too many retries, giving up\n");
+     DRM_ERROR("DPCD: too many retries, giving up!\n");
      err = -EIO;
 
 unlock:

@@ -549,12 +589,12 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
      int max_retries = max(7, drm_dp_i2c_retry_count(msg, dp_aux_i2c_speed_khz));
 
      for (retry = 0, defer_i2c = 0; retry < (max_retries + defer_i2c); retry++) {
-             ret = aux->transfer(aux, msg);
+             ret = aux_transfer(aux, msg);
              if (ret < 0) {
                      if (ret == -EBUSY)
                              continue;
 
-                     DRM_DEBUG_KMS("transaction failed: %d\n", ret);
+                     DRM_DEBUG_AUX("transaction failed: %d\n", ret);
                      return ret;
              }
 

@@ -568,11 +608,11 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
                      break;
 
              case DP_AUX_NATIVE_REPLY_NACK:
-                     DRM_DEBUG_KMS("native nack (result=%d, size=%zu)\n", ret, msg->size);
+                     DRM_DEBUG_AUX("native nack (result=%d, size=%zu)\n", ret, msg->size);
                      return -EREMOTEIO;
 
              case DP_AUX_NATIVE_REPLY_DEFER:
-                     DRM_DEBUG_KMS("native defer\n");
+                     DRM_DEBUG_AUX("native defer\n");
                      /*
                       * We could check for I2C bit rate capabilities and if
                       * available adjust this interval. We could also be

@@ -601,12 +641,12 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
                      return ret;
 
              case DP_AUX_I2C_REPLY_NACK:
-                     DRM_DEBUG_KMS("I2C nack (result=%d, size=%zu\n", ret, msg->size);
+                     DRM_DEBUG_AUX("I2C nack (result=%d, size=%zu)\n", ret, msg->size);
                      aux->i2c_nack_count++;
                      return -EREMOTEIO;
 
              case DP_AUX_I2C_REPLY_DEFER:
-                     DRM_DEBUG_KMS("I2C defer\n");
+                     DRM_DEBUG_AUX("I2C defer\n");
                      /* DP Compliance Test 4.2.2.5 Requirement:
                       * Must have at least 7 retries for I2C defers on the
                       * transaction to pass this test

@@ -625,7 +665,7 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
              }
      }
 
-     DRM_DEBUG_KMS("too many retries, giving up\n");
+     DRM_ERROR("I2C: too many retries, giving up\n");
      return -EREMOTEIO;
 }
 

@@ -653,7 +693,7 @@ static int drm_dp_i2c_drain_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *o
                      return err == 0 ? -EPROTO : err;
 
              if (err < msg.size && err < ret) {
-                     DRM_DEBUG_KMS("Partial I2C reply: requested %zu bytes got %d bytes\n",
+                     DRM_DEBUG_AUX("Partial I2C reply: requested %zu bytes got %d bytes\n",
                                    msg.size, err);
                      ret = err;
              }
include/drm/drmP.h +7 -1
index 3c8422c..cc524b5 100644
@@ -117,7 +117,7 @@ struct dma_buf_attachment;
  * drm.debug=0x2 will enable DRIVER messages
  * drm.debug=0x3 will enable CORE and DRIVER messages
  * ...
- * drm.debug=0x3f will enable all messages
+ * drm.debug=0x7f will enable all messages
  *
  * An interesting feature is that it's possible to enable verbose logging at
  * run-time by echoing the debug value in its sysfs node:

@@ -129,6 +129,7 @@ struct dma_buf_attachment;
 #define DRM_UT_PRIME         0x08
 #define DRM_UT_ATOMIC                0x10
 #define DRM_UT_VBL           0x20
+#define DRM_UT_AUX           0x40
 
 extern __printf(2, 3)
 void drm_ut_debug_printk(const char *function_name,

@@ -226,6 +227,11 @@ void drm_err(const char *format, ...);
              if (unlikely(drm_debug & DRM_UT_VBL))                   \
                      drm_ut_debug_printk(__func__, fmt, ##args);     \
      } while (0)
+#define DRM_DEBUG_AUX(fmt, args...)                                  \
+     do {                                                            \
+             if (unlikely(drm_debug & DRM_UT_AUX))                   \
+                     drm_ut_debug_printk(__func__, fmt, ##args);     \
+     } while (0)
Quoted 2 lines

include/drm/drmP.h void drm_err(const char *format, ...); · line 237

Quoted 2 lines
include/drm/drmP.h +0 -0
 /*@}*/

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Signature · 7 lines
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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#6 lore raw

Re: [PATCH 2/2] drm/dp: add DPCD/AUX logging

Quoted 17 lines · Daniel Vetter
Quoted 16 lines · Rob Clark
Quoted 14 lines · Imre Deak
Quoted 9 lines · Rob Clark

Add a new drm_debug bit for turning on DPCD logging, to aid debugging with troublesome monitors.

v2: don't try to hexdump the universe if driver returns -errno, and change the "too many retries" traces to DRM_ERROR()
v3: rename to more generic "AUX" instead of DP specific DPCD, add DP_AUX_I2C_WRITE_STATUS_UPDATE

Signed-off-by Rob Clark <[email protected]>

I used the rebased version of this after Ville pointed me to it for remote debugging some odd adaptor behavior. It'd be quite useful imo, so:

Acked-by Imre Deak <[email protected]>
Quoted 8 lines
Quoted 4 lines

tbh I completely forgot about this patch.. mind posting the rebased version (or push to a git tree somewhere)?  IIRC there were just some minor cosmetic things to fix up, probably worth doing that before I forget about it again..

There's patches for dynamic debugging floating around, I think that'd be the more interesting approach than adding ever more magic bits that no one understands. But besides that this makes sense.

Ok, although it's better than not having any way to debug and it could be converted to dyndbg with the reset. For reference:
https://github.com/ideak/linux/commits/aux-debug

--Imre

Quoted 202 lines

-Daniel

Quoted 198 lines

BR,
-R

Quoted 186 lines
Quoted 186 lines

---
 drivers/gpu/drm/drm_dp_helper.c | 62 +++++++++++++++++++++++++++++++++-------- include/drm/drmP.h              |  8 +++++-

 2 files changed, 58 insertions(+), 12 deletions(-)
drivers/gpu/drm/drm_dp_helper.c +40 -2
index df64ed1..3ef35fd 100644
@@ -160,6 +160,45 @@ int drm_dp_bw_code_to_link_rate(u8 link_bw)
  }
  EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate);
 
+static ssize_t aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
+{
+     ssize_t ret;
+
+     DRM_DEBUG_AUX("%s: req=0x%02x, address=0x%05x, size=%zu\n", aux->name,
+                     msg->request, msg->address, msg->size);
+
+     if (unlikely(drm_debug & DRM_UT_AUX)) {
+             switch (msg->request & ~DP_AUX_I2C_MOT) {
+             case DP_AUX_NATIVE_WRITE:
+             case DP_AUX_I2C_WRITE:
+             case DP_AUX_I2C_WRITE_STATUS_UPDATE:
+                     print_hex_dump(KERN_DEBUG, "DPCD: ", DUMP_PREFIX_OFFSET,
+                                     16, 1, msg->buffer, msg->size, false);
+                     break;
+             default:
+                     break;
+             }
+     }
+
+     ret = aux->transfer(aux, msg);
+
+     DRM_DEBUG_AUX("%s: reply=0x%02x, size=%zd\n", aux->name, msg->reply, ret);
+
+     if (unlikely(drm_debug & DRM_UT_AUX) && (ret > 0)) {
+             switch (msg->request & ~DP_AUX_I2C_MOT) {
+             case DP_AUX_NATIVE_READ:
+             case DP_AUX_I2C_READ:
+                     print_hex_dump(KERN_DEBUG, "DPCD: ", DUMP_PREFIX_OFFSET,
+                                     16, 1, msg->buffer, ret, false);
+                     break;
+             default:
+                     break;
+             }
+     }
+
+     return ret;
+}
+
  #define AUX_RETRY_INTERVAL 500 /* us */
 
  /**

@@ -197,7 +236,7 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
        */
       for (retry = 0; retry < 32; retry++) {
 
-             err = aux->transfer(aux, &msg);
+             err = aux_transfer(aux, &msg);
               if (err < 0) {
                       if (err == -EBUSY)
                               continue;

@@ -205,7 +244,6 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
                       goto unlock;
               }
 
-
               switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) {

              case DP_AUX_NATIVE_REPLY_ACK:
                      if (err < size)

drivers/gpu/drm/drm_dp_helper.c +0 -0
@@ -213,16 +251,18 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
                       goto unlock;

              case DP_AUX_NATIVE_REPLY_NACK:
+                     DRM_DEBUG_AUX("native nack (result=%d, size=%zu)\n", err, msg.size); err = -EIO;
                      goto unlock;

              case DP_AUX_NATIVE_REPLY_DEFER:
+                     DRM_DEBUG_AUX("native defer\n"); usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100); break;
              }
      }

-     DRM_DEBUG_KMS("too many retries, giving up\n"); +     DRM_ERROR("DPCD: too many retries, giving up!\n"); err = -EIO;

 unlock:

drivers/gpu/drm/drm_dp_helper.c +2 -2
@@ -549,12 +589,12 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
       int max_retries = max(7, drm_dp_i2c_retry_count(msg, dp_aux_i2c_speed_khz));
 
       for (retry = 0, defer_i2c = 0; retry < (max_retries + defer_i2c); retry++) {
-             ret = aux->transfer(aux, msg);
+             ret = aux_transfer(aux, msg);
               if (ret < 0) {
                       if (ret == -EBUSY)
                               continue;
 
-                     DRM_DEBUG_KMS("transaction failed: %d\n", ret);
+                     DRM_DEBUG_AUX("transaction failed: %d\n", ret);
                       return ret;
               }
 

@@ -568,11 +608,11 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
                       break;

              case DP_AUX_NATIVE_REPLY_NACK:
-                     DRM_DEBUG_KMS("native nack (result=%d, size=%zu)\n", ret, msg->size); +                     DRM_DEBUG_AUX("native nack (result=%d, size=%zu)\n", ret, msg->size); return -EREMOTEIO;

              case DP_AUX_NATIVE_REPLY_DEFER:
-                     DRM_DEBUG_KMS("native defer\n");
+                     DRM_DEBUG_AUX("native defer\n");
                      /*
                       * We could check for I2C bit rate capabilities and if
                       * available adjust this interval. We could also be

drivers/gpu/drm/drm_dp_helper.c +0 -0
@@ -601,12 +641,12 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
                       return ret;

              case DP_AUX_I2C_REPLY_NACK:
-                     DRM_DEBUG_KMS("I2C nack (result=%d, size=%zu\n", ret, msg->size); +                     DRM_DEBUG_AUX("I2C nack (result=%d, size=%zu)\n", ret, msg->size); aux->i2c_nack_count++;
                      return -EREMOTEIO;

              case DP_AUX_I2C_REPLY_DEFER:
-                     DRM_DEBUG_KMS("I2C defer\n");
+                     DRM_DEBUG_AUX("I2C defer\n");
                      /* DP Compliance Test 4.2.2.5 Requirement:
                       * Must have at least 7 retries for I2C defers on the
                       * transaction to pass this test

drivers/gpu/drm/drm_dp_helper.c +2 -2
@@ -625,7 +665,7 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
               }
       }
 
-     DRM_DEBUG_KMS("too many retries, giving up\n");
+     DRM_ERROR("I2C: too many retries, giving up\n");
       return -EREMOTEIO;
  }
 

@@ -653,7 +693,7 @@ static int drm_dp_i2c_drain_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *o
                       return err == 0 ? -EPROTO : err;
 
               if (err < msg.size && err < ret) {
-                     DRM_DEBUG_KMS("Partial I2C reply: requested %zu bytes got %d bytes\n",
+                     DRM_DEBUG_AUX("Partial I2C reply: requested %zu bytes got %d bytes\n",
                                     msg.size, err);
                       ret = err;
               }
include/drm/drmP.h +7 -1
index 3c8422c..cc524b5 100644
@@ -117,7 +117,7 @@ struct dma_buf_attachment;
   * drm.debug=0x2 will enable DRIVER messages
   * drm.debug=0x3 will enable CORE and DRIVER messages
   * ...
- * drm.debug=0x3f will enable all messages
+ * drm.debug=0x7f will enable all messages
   *
   * An interesting feature is that it's possible to enable verbose logging at
   * run-time by echoing the debug value in its sysfs node:

@@ -129,6 +129,7 @@ struct dma_buf_attachment;
  #define DRM_UT_PRIME         0x08
  #define DRM_UT_ATOMIC                0x10
  #define DRM_UT_VBL           0x20
+#define DRM_UT_AUX           0x40
 
  extern __printf(2, 3)
  void drm_ut_debug_printk(const char *function_name,

@@ -226,6 +227,11 @@ void drm_err(const char *format, ...);
               if (unlikely(drm_debug & DRM_UT_VBL))                   \
                       drm_ut_debug_printk(__func__, fmt, ##args);     \
       } while (0)
+#define DRM_DEBUG_AUX(fmt, args...)                                  \
+     do {                                                            \
+             if (unlikely(drm_debug & DRM_UT_AUX))                   \
+                     drm_ut_debug_printk(__func__, fmt, ##args);     \
+     } while (0)
Quoted 2 lines

include/drm/drmP.h void drm_err(const char *format, ...); · line 237

Quoted 2 lines
include/drm/drmP.h +0 -0
  /*@}*/

_______________________________________________
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author
#7 lore raw

Re: [PATCH 2/2] drm/dp: add DPCD/AUX logging

In reply to Daniel Vetter
Quoted 17 lines · Daniel Vetter
Quoted 16 lines · Rob Clark
Quoted 14 lines · Imre Deak
Quoted 9 lines · Rob Clark

Add a new drm_debug bit for turning on DPCD logging, to aid debugging with troublesome monitors.

v2: don't try to hexdump the universe if driver returns -errno, and change the "too many retries" traces to DRM_ERROR()
v3: rename to more generic "AUX" instead of DP specific DPCD, add DP_AUX_I2C_WRITE_STATUS_UPDATE

Signed-off-by Rob Clark <[email protected]>

I used the rebased version of this after Ville pointed me to it for remote debugging some odd adaptor behavior. It'd be quite useful imo, so:

Acked-by Imre Deak <[email protected]>
Quoted 8 lines
Quoted 4 lines

tbh I completely forgot about this patch.. mind posting the rebased version (or push to a git tree somewhere)? IIRC there were just some minor cosmetic things to fix up, probably worth doing that before I forget about it again..

There's patches for dynamic debugging floating around, I think that'd be the more interesting approach than adding ever more magic bits that no one understands. But besides that this makes sense.

could make sense.. and by all means if someone wants to take over this patch and do something more clever, go for it..

I won't have access to a dp monitor for a couple weeks, so other than minor cosmetic tweaks there isn't much I can do.. and I mostly don't want this to fall through the cracks again.

BR,
-R

Quoted 200 lines

-Daniel

Quoted 191 lines

BR,
-R

Quoted 186 lines
Quoted 186 lines
---
 drivers/gpu/drm/drm_dp_helper.c | 62 +++++++++++++++++++++++++++++++++--------
 include/drm/drmP.h              |  8 +++++-
 2 files changed, 58 insertions(+), 12 deletions(-)
drivers/gpu/drm/drm_dp_helper.c +51 -11
index df64ed1..3ef35fd 100644
@@ -160,6 +160,45 @@ int drm_dp_bw_code_to_link_rate(u8 link_bw)
 }
 EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate);
 
+static ssize_t aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
+{
+     ssize_t ret;
+
+     DRM_DEBUG_AUX("%s: req=0x%02x, address=0x%05x, size=%zu\n", aux->name,
+                     msg->request, msg->address, msg->size);
+
+     if (unlikely(drm_debug & DRM_UT_AUX)) {
+             switch (msg->request & ~DP_AUX_I2C_MOT) {
+             case DP_AUX_NATIVE_WRITE:
+             case DP_AUX_I2C_WRITE:
+             case DP_AUX_I2C_WRITE_STATUS_UPDATE:
+                     print_hex_dump(KERN_DEBUG, "DPCD: ", DUMP_PREFIX_OFFSET,
+                                     16, 1, msg->buffer, msg->size, false);
+                     break;
+             default:
+                     break;
+             }
+     }
+
+     ret = aux->transfer(aux, msg);
+
+     DRM_DEBUG_AUX("%s: reply=0x%02x, size=%zd\n", aux->name, msg->reply, ret);
+
+     if (unlikely(drm_debug & DRM_UT_AUX) && (ret > 0)) {
+             switch (msg->request & ~DP_AUX_I2C_MOT) {
+             case DP_AUX_NATIVE_READ:
+             case DP_AUX_I2C_READ:
+                     print_hex_dump(KERN_DEBUG, "DPCD: ", DUMP_PREFIX_OFFSET,
+                                     16, 1, msg->buffer, ret, false);
+                     break;
+             default:
+                     break;
+             }
+     }
+
+     return ret;
+}
+
 #define AUX_RETRY_INTERVAL 500 /* us */
 
 /**

@@ -197,7 +236,7 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
       */
      for (retry = 0; retry < 32; retry++) {
 
-             err = aux->transfer(aux, &msg);
+             err = aux_transfer(aux, &msg);
              if (err < 0) {
                      if (err == -EBUSY)
                              continue;

@@ -205,7 +244,6 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
                      goto unlock;
              }
 
-
              switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) {
              case DP_AUX_NATIVE_REPLY_ACK:
                      if (err < size)

@@ -213,16 +251,18 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
                      goto unlock;
 
              case DP_AUX_NATIVE_REPLY_NACK:
+                     DRM_DEBUG_AUX("native nack (result=%d, size=%zu)\n", err, msg.size);
                      err = -EIO;
                      goto unlock;
 
              case DP_AUX_NATIVE_REPLY_DEFER:
+                     DRM_DEBUG_AUX("native defer\n");
                      usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100);
                      break;
              }
      }
 
-     DRM_DEBUG_KMS("too many retries, giving up\n");
+     DRM_ERROR("DPCD: too many retries, giving up!\n");
      err = -EIO;
 
 unlock:

@@ -549,12 +589,12 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
      int max_retries = max(7, drm_dp_i2c_retry_count(msg, dp_aux_i2c_speed_khz));
 
      for (retry = 0, defer_i2c = 0; retry < (max_retries + defer_i2c); retry++) {
-             ret = aux->transfer(aux, msg);
+             ret = aux_transfer(aux, msg);
              if (ret < 0) {
                      if (ret == -EBUSY)
                              continue;
 
-                     DRM_DEBUG_KMS("transaction failed: %d\n", ret);
+                     DRM_DEBUG_AUX("transaction failed: %d\n", ret);
                      return ret;
              }
 

@@ -568,11 +608,11 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
                      break;
 
              case DP_AUX_NATIVE_REPLY_NACK:
-                     DRM_DEBUG_KMS("native nack (result=%d, size=%zu)\n", ret, msg->size);
+                     DRM_DEBUG_AUX("native nack (result=%d, size=%zu)\n", ret, msg->size);
                      return -EREMOTEIO;
 
              case DP_AUX_NATIVE_REPLY_DEFER:
-                     DRM_DEBUG_KMS("native defer\n");
+                     DRM_DEBUG_AUX("native defer\n");
                      /*
                       * We could check for I2C bit rate capabilities and if
                       * available adjust this interval. We could also be

@@ -601,12 +641,12 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
                      return ret;
 
              case DP_AUX_I2C_REPLY_NACK:
-                     DRM_DEBUG_KMS("I2C nack (result=%d, size=%zu\n", ret, msg->size);
+                     DRM_DEBUG_AUX("I2C nack (result=%d, size=%zu)\n", ret, msg->size);
                      aux->i2c_nack_count++;
                      return -EREMOTEIO;
 
              case DP_AUX_I2C_REPLY_DEFER:
-                     DRM_DEBUG_KMS("I2C defer\n");
+                     DRM_DEBUG_AUX("I2C defer\n");
                      /* DP Compliance Test 4.2.2.5 Requirement:
                       * Must have at least 7 retries for I2C defers on the
                       * transaction to pass this test

@@ -625,7 +665,7 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
              }
      }
 
-     DRM_DEBUG_KMS("too many retries, giving up\n");
+     DRM_ERROR("I2C: too many retries, giving up\n");
      return -EREMOTEIO;
 }
 

@@ -653,7 +693,7 @@ static int drm_dp_i2c_drain_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *o
                      return err == 0 ? -EPROTO : err;
 
              if (err < msg.size && err < ret) {
-                     DRM_DEBUG_KMS("Partial I2C reply: requested %zu bytes got %d bytes\n",
+                     DRM_DEBUG_AUX("Partial I2C reply: requested %zu bytes got %d bytes\n",
                                    msg.size, err);
                      ret = err;
              }
include/drm/drmP.h +7 -1
index 3c8422c..cc524b5 100644
@@ -117,7 +117,7 @@ struct dma_buf_attachment;
  * drm.debug=0x2 will enable DRIVER messages
  * drm.debug=0x3 will enable CORE and DRIVER messages
  * ...
- * drm.debug=0x3f will enable all messages
+ * drm.debug=0x7f will enable all messages
  *
  * An interesting feature is that it's possible to enable verbose logging at
  * run-time by echoing the debug value in its sysfs node:

@@ -129,6 +129,7 @@ struct dma_buf_attachment;
 #define DRM_UT_PRIME         0x08
 #define DRM_UT_ATOMIC                0x10
 #define DRM_UT_VBL           0x20
+#define DRM_UT_AUX           0x40
 
 extern __printf(2, 3)
 void drm_ut_debug_printk(const char *function_name,

@@ -226,6 +227,11 @@ void drm_err(const char *format, ...);
              if (unlikely(drm_debug & DRM_UT_VBL))                   \
                      drm_ut_debug_printk(__func__, fmt, ##args);     \
      } while (0)
+#define DRM_DEBUG_AUX(fmt, args...)                                  \
+     do {                                                            \
+             if (unlikely(drm_debug & DRM_UT_AUX))                   \
+                     drm_ut_debug_printk(__func__, fmt, ##args);     \
+     } while (0)
Quoted 6 lines
Quoted 2 lines

include/drm/drmP.h void drm_err(const char *format, ...); · line 237

Quoted 2 lines
include/drm/drmP.h +0 -0
 /*@}*/

_______________________________________________
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[email protected]
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Quoted 4 lines

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

_______________________________________________
dri-devel mailing list
[email protected]
https://lists.freedesktop.org/mailman/listinfo/dri-devel

Reviewed-by on v1 1/2
#8 lore raw
In reply to Rob Clark
Quoted 9 lines · Rob Clark

1) don't let other threads trying to bang on aux channel interrupt the defer timeout/logic
2) don't let other threads interrupt the i2c over aux logic

Technically, according to people who actually have the DP spec, this should not be required. In practice, it makes some troublesome Dell monitor (and perhaps others) work, so probably a case of "It's compliant if it works with windows" on the hw vendor's part..

Quoted 7 lines

v2: rebased to come before DPCD/AUX logging patch for easier backport to stable branches.

Reported-by Dave Wysochanski <[email protected]>

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1274157

Cc [email protected]
Signed-off-by Rob Clark <[email protected]>
Reviewed-by Daniel Vetter <[email protected]>

Dave, can you pls pick up?

Thanks, Daniel

Quoted 101 lines
---
 drivers/gpu/drm/drm_dp_helper.c | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)
drivers/gpu/drm/drm_dp_helper.c +17 -10
index 7d58f59..df64ed1 100644
@@ -179,7 +179,7 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
 {
 	struct drm_dp_aux_msg msg;
 	unsigned int retry;
-	int err;
+	int err = 0;
 
 	memset(&msg, 0, sizeof(msg));
 	msg.address = offset;

@@ -187,6 +187,8 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
 	msg.buffer = buffer;
 	msg.size = size;
 
+	mutex_lock(&aux->hw_mutex);
+
 	/*
 	 * The specification doesn't give any recommendation on how often to
 	 * retry native transactions. We used to retry 7 times like for

@@ -195,25 +197,24 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
 	 */
 	for (retry = 0; retry < 32; retry++) {
 
-		mutex_lock(&aux->hw_mutex);
 		err = aux->transfer(aux, &msg);
-		mutex_unlock(&aux->hw_mutex);
 		if (err < 0) {
 			if (err == -EBUSY)
 				continue;
 
-			return err;
+			goto unlock;
 		}
 
 
 		switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) {
 		case DP_AUX_NATIVE_REPLY_ACK:
 			if (err < size)
-				return -EPROTO;
-			return err;
+				err = -EPROTO;
+			goto unlock;
 
 		case DP_AUX_NATIVE_REPLY_NACK:
-			return -EIO;
+			err = -EIO;
+			goto unlock;
 
 		case DP_AUX_NATIVE_REPLY_DEFER:
 			usleep_range(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100);

@@ -222,7 +223,11 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
 	}
 
 	DRM_DEBUG_KMS("too many retries, giving up\n");
-	return -EIO;
+	err = -EIO;
+
+unlock:
+	mutex_unlock(&aux->hw_mutex);
+	return err;
 }
 
 /**

@@ -544,9 +549,7 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 	int max_retries = max(7, drm_dp_i2c_retry_count(msg, dp_aux_i2c_speed_khz));
 
 	for (retry = 0, defer_i2c = 0; retry < (max_retries + defer_i2c); retry++) {
-		mutex_lock(&aux->hw_mutex);
 		ret = aux->transfer(aux, msg);
-		mutex_unlock(&aux->hw_mutex);
 		if (ret < 0) {
 			if (ret == -EBUSY)
 				continue;

@@ -685,6 +688,8 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
 
 	memset(&msg, 0, sizeof(msg));
 
+	mutex_lock(&aux->hw_mutex);
+
 	for (i = 0; i < num; i++) {
 		msg.address = msgs[i].addr;
 		drm_dp_i2c_msg_set_request(&msg, &msgs[i]);

@@ -739,6 +744,8 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
 	msg.size = 0;
 	(void)drm_dp_i2c_do_msg(aux, &msg);
 
+	mutex_unlock(&aux->hw_mutex);
+
 	return err;
 }
Signature · 1 line
2.5.0
Signature · 7 lines
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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