Implement CRC and Add necessary infrastructure

This patch add the necessary functions to map/unmap GEM backing memory to the kernel's virtual address space.

Signed-off-by Haneen Mohammed <[email protected]>

---
Changes in v2:
- add vkms_gem_vunmap
- use vmap_count to guard against multiple prepare_fb calls on the same fb
Changes in v3:
- change vkms_gem_vmap to retrun int
- cleanup if vmap failed
- increment vmap_count after successful vmap

 drivers/gpu/drm/vkms/vkms_drv.h |  9 ++++
 drivers/gpu/drm/vkms/vkms_gem.c | 80 ++++++++++++++++++++++++++++++++-
 2 files changed, 88 insertions(+), 1 deletion(-)

drivers/gpu/drm/vkms/vkms_drv.h +9 -0

index 07be29f2dc44..47048f707566 100644
@@ -39,6 +39,8 @@ struct vkms_gem_object {
 	struct drm_gem_object gem;
 	struct mutex pages_lock; /* Page lock used in page fault handler */
 	struct page **pages;
+	unsigned int vmap_count;
+	void *vaddr;
 };
 
 #define drm_crtc_to_vkms_output(target) \

@@ -47,6 +49,9 @@ struct vkms_gem_object {
 #define drm_device_to_vkms_device(target) \
 	container_of(target, struct vkms_device, drm)
 
+#define drm_gem_to_vkms_gem(target)\
+	container_of(target, struct vkms_gem_object, gem)
+
 /* CRTC */
 int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc,
 		   struct drm_plane *primary, struct drm_plane *cursor);

@@ -75,4 +80,8 @@ int vkms_dumb_map(struct drm_file *file, struct drm_device *dev,
 
 void vkms_gem_free_object(struct drm_gem_object *obj);
 
+int vkms_gem_vmap(struct drm_gem_object *obj);
+
+void vkms_gem_vunmap(struct drm_gem_object *obj);
+
 #endif /* _VKMS_DRV_H_ */

drivers/gpu/drm/vkms/vkms_gem.c +66 -1

index c7e38368602b..2e55c906d9b2 100644
@@ -37,7 +37,9 @@ void vkms_gem_free_object(struct drm_gem_object *obj)
 	struct vkms_gem_object *gem = container_of(obj, struct vkms_gem_object,
 						   gem);
 
-	kvfree(gem->pages);
+	WARN_ON(gem->pages);
+	WARN_ON(gem->vaddr);
+
 	mutex_destroy(&gem->pages_lock);
 	drm_gem_object_release(obj);
 	kfree(gem);

@@ -177,3 +179,79 @@ int vkms_dumb_map(struct drm_file *file, struct drm_device *dev,
 
 	return ret;
 }
+
+static struct page **_get_pages(struct vkms_gem_object *vkms_obj)
+{
+	struct drm_gem_object *gem_obj = &vkms_obj->gem;
+
+	if (!vkms_obj->pages) {
+		struct page **pages = drm_gem_get_pages(gem_obj);
+
+		if (IS_ERR(pages))
+			return pages;
+
+		if (cmpxchg(&vkms_obj->pages, NULL, pages))
+			drm_gem_put_pages(gem_obj, pages, false, true);
+	}
+
+	return vkms_obj->pages;
+}
+
+void vkms_gem_vunmap(struct drm_gem_object *obj)
+{
+	struct vkms_gem_object *vkms_obj = drm_gem_to_vkms_gem(obj);
+
+	mutex_lock(&vkms_obj->pages_lock);
+	if (vkms_obj->vmap_count < 1) {
+		WARN_ON(vkms_obj->vaddr);
+		WARN_ON(vkms_obj->pages);
+		mutex_unlock(&vkms_obj->pages_lock);
+		return;
+	}
+
+	vkms_obj->vmap_count--;
+
+	if (vkms_obj->vmap_count == 0) {
+		vunmap(vkms_obj->vaddr);
+		vkms_obj->vaddr = NULL;
+		drm_gem_put_pages(obj, vkms_obj->pages, false, true);
+		vkms_obj->pages = NULL;
+	}
+
+	mutex_unlock(&vkms_obj->pages_lock);
+}
+
+int vkms_gem_vmap(struct drm_gem_object *obj)
+{
+	struct vkms_gem_object *vkms_obj = drm_gem_to_vkms_gem(obj);
+	int ret = 0;
+
+	mutex_lock(&vkms_obj->pages_lock);
+
+	if (!vkms_obj->vaddr) {
+		unsigned int n_pages = obj->size >> PAGE_SHIFT;
+		struct page **pages = _get_pages(vkms_obj);
+
+		if (IS_ERR(pages)) {
+			ret = PTR_ERR(pages);
+			goto fail;
+		}
+
+		vkms_obj->vaddr = vmap(pages, n_pages, VM_MAP, PAGE_KERNEL);
+		if (!vkms_obj->vaddr) {
+			ret = -ENOMEM;
+			drm_gem_put_pages(obj, vkms_obj->pages, false, true);
+			vkms_obj->pages = NULL;

drivers/gpu/drm/vkms/vkms_gem.c +3 -0

+	mutex_unlock(&vkms_obj->pages_lock);
+	return ret;
+}

Signature · 1 line

2.17.1

This patch map/unmap GEM backing memory to kernel address space in prepare/cleanup_fb respectively and cache the virtual address for later use.

Signed-off-by Haneen Mohammed <[email protected]>

---
Changes in v2:
- use vkms_gem_vunmap

Changes in v3:
- return error number instead of vkms_obj->vaddr

 drivers/gpu/drm/vkms/vkms_plane.c | 35 +++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

drivers/gpu/drm/vkms/vkms_plane.c +5 -0

index 9f75b1e2c1c4..aa6cde34710c 100644
@@ -9,6 +9,7 @@
 #include "vkms_drv.h"
 #include <drm/drm_plane_helper.h>
 #include <drm/drm_atomic_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
 
 static const struct drm_plane_funcs vkms_plane_funcs = {
 	.update_plane		= drm_atomic_helper_update_plane,

@@ -24,8 +25,42 @@ static void vkms_primary_plane_update(struct drm_plane *plane,
 {
 }
 
+static int vkms_prepare_fb(struct drm_plane *plane,
+			   struct drm_plane_state *state)
+{
+	struct drm_gem_object *gem_obj;

drivers/gpu/drm/vkms/vkms_plane.c +18 -0

+
+	return drm_gem_fb_prepare_fb(plane, state);
+}
+
+static void vkms_cleanup_fb(struct drm_plane *plane,
+			    struct drm_plane_state *old_state)
+{
+	struct drm_gem_object *gem_obj;
+
+	if (!old_state->fb)
+		return;
+
+	gem_obj = drm_gem_fb_get_obj(old_state->fb, 0);
+	vkms_gem_vunmap(gem_obj);
+}
+
 static const struct drm_plane_helper_funcs vkms_primary_helper_funcs = {
 	.atomic_update		= vkms_primary_plane_update,
+	.prepare_fb		= vkms_prepare_fb,
+	.cleanup_fb		= vkms_cleanup_fb,
 };
 
 struct drm_plane *vkms_plane_init(struct vkms_device *vkmsdev)

Signature · 1 line

2.17.1

Implement the set_crc_source() callback.
Compute CRC using crc32 on the visible part of the framebuffer. Use ordered workqueue to compute and add CRC at the end of a vblank.

Use appropriate synchronization methods since the CRC computation must be atomic wrt the generated vblank event for a given atomic update, by using spinlock across atomic_begin and atomic_flush to wrap the event handling code completely and match the flip event with the CRC.

Signed-off-by Haneen Mohammed <[email protected]>

---
Changes in v3:
- flush work item instead of workqueue
- include missing vkms_crc.c file

 drivers/gpu/drm/vkms/Makefile     |  2 +-
 drivers/gpu/drm/vkms/vkms_crc.c   | 66 +++++++++++++++++++++++++++++++
 drivers/gpu/drm/vkms/vkms_crtc.c  | 58 ++++++++++++++++++++++-----
 drivers/gpu/drm/vkms/vkms_drv.c   |  1 +
 drivers/gpu/drm/vkms/vkms_drv.h   | 21 ++++++++++
 drivers/gpu/drm/vkms/vkms_plane.c | 10 +++++
 6 files changed, 148 insertions(+), 10 deletions(-)
 create mode 100644 drivers/gpu/drm/vkms/vkms_crc.c

drivers/gpu/drm/vkms/Makefile +1 -1

index 986297da51bf..37966914f70b 100644
@@ -1,3 +1,3 @@
-vkms-y := vkms_drv.o vkms_plane.o vkms_output.o vkms_crtc.o vkms_gem.o
+vkms-y := vkms_drv.o vkms_plane.o vkms_output.o vkms_crtc.o vkms_gem.o vkms_crc.o
 
 obj-$(CONFIG_DRM_VKMS) += vkms.o

drivers/gpu/drm/vkms/vkms_crc.c new file +10 -0

new file mode 100644
index 000000000000..9e8bb5c7fc80
@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "vkms_drv.h"
+#include <linux/crc32.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+
+static uint32_t _vkms_get_crc(struct vkms_crc_data *crc_data)
+{
+	struct drm_framebuffer *fb = &crc_data->fb;
+	struct drm_gem_object *gem_obj = drm_gem_fb_get_obj(fb, 0);
+	struct vkms_gem_object *vkms_obj = drm_gem_to_vkms_gem(gem_obj);

drivers/gpu/drm/vkms/vkms_crc.c new file +23 -0

+
+	if (WARN_ON(!vaddr))
+		return crc;
+
+	for (i = y; i < y + height; i++) {
+		src_offset = fb->offsets[0] + (i * fb->pitches[0]) + (x * cpp);
+		crc = crc32_le(crc, vaddr + src_offset, size_byte);
+	}
+
+	return crc;
+}
+
+void vkms_crc_work_handle(struct work_struct *work)
+{
+	struct vkms_crtc_state *crtc_state = container_of(work,
+						struct vkms_crtc_state,
+						crc_work);
+	struct drm_crtc *crtc = crtc_state->base.crtc;
+	struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
+
+	if (crtc_state && out->crc_enabled) {
+		u32 crc32 = _vkms_get_crc(&crtc_state->data);
+		unsigned int n_frame = crtc_state->n_frame;

drivers/gpu/drm/vkms/vkms_crc.c new file +13 -0

+	if (!src_name) {
+		out->crc_enabled = false;
+	} else if (strcmp(src_name, "auto") == 0) {
+		out->crc_enabled = true;
+	} else {
+		out->crc_enabled = false;
+		return -EINVAL;
+	}
+
+	*values_cnt = 1;
+
+	return 0;
+}

drivers/gpu/drm/vkms/vkms_crtc.c +22 -5

index 26babb85ca77..a7b39627b581 100644
@@ -10,17 +10,32 @@
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_crtc_helper.h>
 
-static enum hrtimer_restart vkms_vblank_simulate(struct hrtimer *timer)
+static void _vblank_handle(struct vkms_output *output)
 {
-	struct vkms_output *output = container_of(timer, struct vkms_output,
-						  vblank_hrtimer);
 	struct drm_crtc *crtc = &output->crtc;
-	int ret_overrun;
+	struct vkms_crtc_state *state = to_vkms_crtc_state(crtc->state);
 	bool ret;
 
+	spin_lock(&output->lock);
 	ret = drm_crtc_handle_vblank(crtc);
 	if (!ret)
-		DRM_ERROR("vkms failure on handling vblank");
+		DRM_ERROR("vkms failure on handling vblank\n");
+
+	if (state && output->crc_enabled) {
+		state->n_frame = drm_crtc_accurate_vblank_count(crtc);
+		queue_work(output->crc_workq, &state->crc_work);
+	}
+
+	spin_unlock(&output->lock);
+}
+
+static enum hrtimer_restart vkms_vblank_simulate(struct hrtimer *timer)
+{
+	struct vkms_output *output = container_of(timer, struct vkms_output,
+						  vblank_hrtimer);
+	int ret_overrun;
+
+	_vblank_handle(output);
 
 	ret_overrun = hrtimer_forward_now(&output->vblank_hrtimer,
 					  output->period_ns);

@@ -97,6 +112,8 @@ vkms_atomic_crtc_duplicate_state(struct drm_crtc *crtc)
 
 	__drm_atomic_helper_crtc_duplicate_state(crtc, &vkms_state->base);
 
+	INIT_WORK(&vkms_state->crc_work, vkms_crc_work_handle);
+
 	return &vkms_state->base;
 }
 

drivers/gpu/drm/vkms/vkms_crtc.c +4 -0

+		memset(&vkms_state->data, 0, sizeof(struct vkms_crc_data));
+		kfree(vkms_state);
+	}
 }
 
 static const struct drm_crtc_funcs vkms_crtc_funcs = {

@@ -120,6 +143,7 @@ static const struct drm_crtc_funcs vkms_crtc_funcs = {
 	.atomic_destroy_state   = vkms_atomic_crtc_destroy_state,
 	.enable_vblank		= vkms_enable_vblank,
 	.disable_vblank		= vkms_disable_vblank,
+	.set_crc_source		= vkms_set_crc_source,
 };
 
 static void vkms_crtc_atomic_enable(struct drm_crtc *crtc,

drivers/gpu/drm/vkms/vkms_crtc.c +9 -1

 		if (drm_crtc_vblank_get(crtc) != 0)
 			drm_crtc_send_vblank_event(crtc, crtc->state->event);
 		else
 			drm_crtc_arm_vblank_event(crtc, crtc->state->event);
 
-		spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
+		spin_unlock(&crtc->dev->event_lock);
 
 		crtc->state->event = NULL;
 	}
+
+	spin_unlock_irq(&vkms_output->lock);
 }
 
 static const struct drm_crtc_helper_funcs vkms_crtc_helper_funcs = {
+	.atomic_begin	= vkms_crtc_atomic_begin,
 	.atomic_flush	= vkms_crtc_atomic_flush,
 	.atomic_enable	= vkms_crtc_atomic_enable,
 	.atomic_disable	= vkms_crtc_atomic_disable,

@@ -162,6 +197,7 @@ static const struct drm_crtc_helper_funcs vkms_crtc_helper_funcs = {
 int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc,
 		   struct drm_plane *primary, struct drm_plane *cursor)
 {
+	struct vkms_output *vkms_out = drm_crtc_to_vkms_output(crtc);
 	int ret;
 
 	ret = drm_crtc_init_with_planes(dev, crtc, primary, cursor,

@@ -173,5 +209,9 @@ int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc,
 
 	drm_crtc_helper_add(crtc, &vkms_crtc_helper_funcs);
 
+	spin_lock_init(&vkms_out->lock);
+
+	vkms_out->crc_workq = alloc_ordered_workqueue("vkms_crc_workq", 0);
+
 	return ret;
 }

drivers/gpu/drm/vkms/vkms_drv.c +1 -0

index 37aa2ef33b21..5d78bd97e69c 100644
@@ -46,6 +46,7 @@ static void vkms_release(struct drm_device *dev)
 	platform_device_unregister(vkms->platform);
 	drm_mode_config_cleanup(&vkms->drm);
 	drm_dev_fini(&vkms->drm);
+	destroy_workqueue(vkms->output.crc_workq);
 }
 
 static struct drm_driver vkms_driver = {

drivers/gpu/drm/vkms/vkms_drv.h +21 -0

index 75e52d61e65d..a80281a12010 100644
@@ -20,12 +20,23 @@ static const u32 vkms_formats[] = {
 	DRM_FORMAT_XRGB8888,
 };
 
+struct vkms_crc_data {
+	struct drm_rect src;
+	struct drm_framebuffer fb;
+};
+
 /**
  * vkms_crtc_state - Driver specific CRTC state
  * @base: base CRTC state
+ * @crc_work: work struct to compute and add CRC entries
+ * @data: data required for CRC computation
+ * @n_frame: frame number for computed CRC
  */
 struct vkms_crtc_state {
 	struct drm_crtc_state base;
+	struct work_struct crc_work;
+	struct vkms_crc_data data;
+	unsigned int n_frame;
 };
 
 struct vkms_output {

@@ -35,6 +46,11 @@ struct vkms_output {
 	struct hrtimer vblank_hrtimer;
 	ktime_t period_ns;
 	struct drm_pending_vblank_event *event;
+	bool crc_enabled;
+	/* ordered wq for crc_work */
+	struct workqueue_struct *crc_workq;
+	/* protects concurrent access to crc_data */
+	spinlock_t lock;
 };
 
 struct vkms_device {

@@ -95,4 +111,9 @@ int vkms_gem_vmap(struct drm_gem_object *obj);
 
 void vkms_gem_vunmap(struct drm_gem_object *obj);
 
+/* CRC Support */
+int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name,
+			size_t *values_cnt);
+void vkms_crc_work_handle(struct work_struct *work);
+
 #endif /* _VKMS_DRV_H_ */

drivers/gpu/drm/vkms/vkms_plane.c +0 -0

index 5b7c5d59f103..b316b2af88ee 100644
@@ -24,6 +24,16 @@ static const struct drm_plane_funcs vkms_plane_funcs = {
 static void vkms_primary_plane_update(struct drm_plane *plane,
 				      struct drm_plane_state *old_state)
 {

drivers/gpu/drm/vkms/vkms_plane.c +0 -0

 }
 
 static int vkms_plane_atomic_check(struct drm_plane *plane,

Signature · 1 line

2.17.1