drm/dp_helper: don't return EPROTO for defers (v2)

From: Dave Airlie <[email protected]>

If we get a msg.reply of REPLY_DEFER, we also get an err of 0 so we fail reads with 0 < size and return -EPROTO instead of trying again.

v2: same fix in i2c code.

Found writing MST support.

Signed-off-by Dave Airlie <[email protected]>

---
 drivers/gpu/drm/drm_dp_helper.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

drivers/gpu/drm/drm_dp_helper.c +4 -4

index f4babed..2767148 100644
@@ -386,11 +386,11 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
 			return err;
 		}
 
-		if (err < size)
-			return -EPROTO;
 
 		switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) {
 		case DP_AUX_NATIVE_REPLY_ACK:
+			if (err < size)
+				return -EPROTO;
 			return err;
 
 		case DP_AUX_NATIVE_REPLY_NACK:

@@ -599,8 +599,6 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 			return err;
 		}
 
-		if (err < msg->size)
-			return -EPROTO;
 
 		switch (msg->reply & DP_AUX_NATIVE_REPLY_MASK) {
 		case DP_AUX_NATIVE_REPLY_ACK:

@@ -639,6 +637,8 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 			 * Both native ACK and I2C ACK replies received. We
 			 * can assume the transfer was successful.
 			 */
+			if (err < msg->size)
+				return -EPROTO;
 			return 0;
 
 		case DP_AUX_I2C_REPLY_NACK:

Signature · 6 lines

1.8.5.3

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