diff mbox series

[2/2] drm/vkms: Implement CRC debugfs API

Message ID b42fcf10cfefc7995542a942457a6bcb33f3da79.1532767204.git.hamohammed.sa@gmail.com (mailing list archive)
State New, archived
Headers show
Series drm/vkms: Add CRC support | expand

Commit Message

Haneen Mohammed July 28, 2018, 9:11 a.m. UTC 
This patch implement the necessary functions to compute and add CRCs
entries:

- Implement the set_crc_source() callback.
- Compute CRC using crc32 on the visible part of the framebuffer.
- Use ordered workqueue per output 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/atomic_flush to wrap the event
  handling code completely and match the flip event with the CRC.

Since vkms_crc_work_handle() can sleep, spinlock can't be acquired
while accessing vkms_output->primary_crc to compute CRC.
To make sure the data is updated and released without conflict with
the vkms_crc_work_handle(), the work_struct is flushed @crtc_destroy
and the data is updated before scheduling the work handle again, as
follow:

* CRC data update:
1- store vkms_crc_data {fb, src} per plane_state
2- @plane_duplicate_state -> allocate vkms_crc_data
3- during atomic commit (@atomic_update) ->
	a) copy {fb, src} to plane_state->crc_data
	b) get reference to fb,
3- @plane_destroy_state -> a) if (fb refcount) remove reference to fb
			   b) deallocate crc_data

* Atomic Commit:
1- vkms_plane_atomic_check
2- vkms_prepare_fb -> vmap vkms_gem_obj->vaddr
3- atomic_begin -> hold crc spinlock
4- atomic_plane_update -> a) update vkms_output->primary_crc
			  b) get reference to fb
5- atomic_flush -> a) send vblank event while holding event_lock
		   b) release crc spinlock

* hrtimer regular callback:
1- hold crc spinlock
2- drm_crtc_handle_vblank()
3- queue vkms_crc_work_handle
4- release crc spinlock

* cleanup:
1- @cleanup_fb ->vunmap vkms_gem_obj->vaddr
2- @crtc_destroy -> flush work struct
3- @plane_destroy -> a) if (fb refcount) remove reference to fb
		     b) deallocate crc_data

Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com>
---
 drivers/gpu/drm/vkms/Makefile     |  2 +-
 drivers/gpu/drm/vkms/vkms_crc.c   | 75 +++++++++++++++++++++++++++++++
 drivers/gpu/drm/vkms/vkms_crtc.c  | 56 +++++++++++++++++++----
 drivers/gpu/drm/vkms/vkms_drv.c   |  1 +
 drivers/gpu/drm/vkms/vkms_drv.h   | 22 +++++++++
 drivers/gpu/drm/vkms/vkms_plane.c | 44 ++++++++++++++++++
 6 files changed, 191 insertions(+), 9 deletions(-)
 create mode 100644 drivers/gpu/drm/vkms/vkms_crc.c

Comments

Sean Paul July 31, 2018, 6:01 p.m. UTC | #1 
On Sat, Jul 28, 2018 at 12:11:53PM +0300, Haneen Mohammed wrote:
> This patch implement the necessary functions to compute and add CRCs
> entries:
> 
> - Implement the set_crc_source() callback.
> - Compute CRC using crc32 on the visible part of the framebuffer.
> - Use ordered workqueue per output 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/atomic_flush to wrap the event
>   handling code completely and match the flip event with the CRC.
> 
> Since vkms_crc_work_handle() can sleep, spinlock can't be acquired
> while accessing vkms_output->primary_crc to compute CRC.
> To make sure the data is updated and released without conflict with
> the vkms_crc_work_handle(), the work_struct is flushed @crtc_destroy
> and the data is updated before scheduling the work handle again, as
> follow:
> 
> * CRC data update:
> 1- store vkms_crc_data {fb, src} per plane_state
> 2- @plane_duplicate_state -> allocate vkms_crc_data
> 3- during atomic commit (@atomic_update) ->
> 	a) copy {fb, src} to plane_state->crc_data
> 	b) get reference to fb,
> 3- @plane_destroy_state -> a) if (fb refcount) remove reference to fb
> 			   b) deallocate crc_data
> 
> * Atomic Commit:
> 1- vkms_plane_atomic_check
> 2- vkms_prepare_fb -> vmap vkms_gem_obj->vaddr
> 3- atomic_begin -> hold crc spinlock
> 4- atomic_plane_update -> a) update vkms_output->primary_crc
> 			  b) get reference to fb
> 5- atomic_flush -> a) send vblank event while holding event_lock
> 		   b) release crc spinlock
> 
> * hrtimer regular callback:
> 1- hold crc spinlock
> 2- drm_crtc_handle_vblank()
> 3- queue vkms_crc_work_handle
> 4- release crc spinlock
> 
> * cleanup:
> 1- @cleanup_fb ->vunmap vkms_gem_obj->vaddr
> 2- @crtc_destroy -> flush work struct
> 3- @plane_destroy -> a) if (fb refcount) remove reference to fb
> 		     b) deallocate crc_data
> 
> Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com>
> ---
>  drivers/gpu/drm/vkms/Makefile     |  2 +-
>  drivers/gpu/drm/vkms/vkms_crc.c   | 75 +++++++++++++++++++++++++++++++
>  drivers/gpu/drm/vkms/vkms_crtc.c  | 56 +++++++++++++++++++----
>  drivers/gpu/drm/vkms/vkms_drv.c   |  1 +
>  drivers/gpu/drm/vkms/vkms_drv.h   | 22 +++++++++
>  drivers/gpu/drm/vkms/vkms_plane.c | 44 ++++++++++++++++++
>  6 files changed, 191 insertions(+), 9 deletions(-)
>  create mode 100644 drivers/gpu/drm/vkms/vkms_crc.c
> 
> diff --git a/drivers/gpu/drm/vkms/Makefile b/drivers/gpu/drm/vkms/Makefile
> index 986297da51bf..37966914f70b 100644
> --- a/drivers/gpu/drm/vkms/Makefile
> +++ b/drivers/gpu/drm/vkms/Makefile
> @@ -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
> diff --git a/drivers/gpu/drm/vkms/vkms_crc.c b/drivers/gpu/drm/vkms/vkms_crc.c
> new file mode 100644
> index 000000000000..d4f94ac932a7
> --- /dev/null
> +++ b/drivers/gpu/drm/vkms/vkms_crc.c
> @@ -0,0 +1,75 @@
> +// 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);
> +	u32 crc = 0;
> +	int i = 0;
> +	unsigned int x = crc_data->src.x1 >> 16;
> +	unsigned int y = crc_data->src.y1 >> 16;
> +	unsigned int height = drm_rect_height(&crc_data->src) >> 16;
> +	unsigned int width = drm_rect_width(&crc_data->src) >> 16;
> +	unsigned int cpp = fb->format->cpp[0];
> +	unsigned int src_offset;
> +	unsigned int size_byte = width * cpp;
> +	void *vaddr;
> +
> +	mutex_lock(&vkms_obj->pages_lock);
> +	vaddr = vkms_obj->vaddr;
> +	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);
> +	}
> +	mutex_unlock(&vkms_obj->pages_lock);
> +
> +	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) {
> +		unsigned int n_frame = crtc_state->n_frame;
> +		u32 crc32 = 0;
> +
> +		if (out->primary_crc)
> +			crc32 = _vkms_get_crc(out->primary_crc);
> +
> +		drm_crtc_add_crc_entry(crtc, true, n_frame, &crc32);
> +	}
> +}
> +
> +int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name,
> +			size_t *values_cnt)
> +{
> +	struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
> +	bool enabled = false;
> +	unsigned long flags;
> +	int ret = 0;
> +
> +	if (src_name && strcmp(src_name, "auto") == 0)
> +		enabled = true;
> +	else if (src_name)
> +		ret = -EINVAL;
> +
> +	*values_cnt = 1;
> +
> +	spin_lock_irqsave(&out->lock, flags);
> +	out->crc_enabled = enabled;
> +	spin_unlock_irqrestore(&out->lock, flags);
> +
> +	return ret;
> +}
> diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
> index 26babb85ca77..a6c080d7f7ae 100644
> --- a/drivers/gpu/drm/vkms/vkms_crtc.c
> +++ b/drivers/gpu/drm/vkms/vkms_crtc.c
> @@ -10,18 +10,33 @@
>  #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");
>  
> +	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);
>  
> @@ -97,18 +112,22 @@ 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;
>  }
>  
>  static void vkms_atomic_crtc_destroy_state(struct drm_crtc *crtc,
>  					   struct drm_crtc_state *state)
>  {
> -	struct vkms_crtc_state *vkms_state;
> -
> -	vkms_state = to_vkms_crtc_state(state);
> +	struct vkms_crtc_state *vkms_state = to_vkms_crtc_state(state);
>  
>  	__drm_atomic_helper_crtc_destroy_state(state);
> -	kfree(vkms_state);
> +
> +	if (vkms_state) {
> +		flush_work(&vkms_state->crc_work);
> +		kfree(vkms_state);
> +	}
>  }
>  
>  static const struct drm_crtc_funcs vkms_crtc_funcs = {
> @@ -120,6 +139,7 @@ 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,
> @@ -134,9 +154,21 @@ static void vkms_crtc_atomic_disable(struct drm_crtc *crtc,
>  	drm_crtc_vblank_off(crtc);
>  }
>  
> +static void vkms_crtc_atomic_begin(struct drm_crtc *crtc,
> +				   struct drm_crtc_state *old_crtc_state)
> +{
> +	struct vkms_output *vkms_output = drm_crtc_to_vkms_output(crtc);
> +
> +	/* This lock is held across the atomic commit to block vblamk timer
> +	 * from scheduling vkms_crc_work_handle until the crc_data is updated
> +	 */
> +	spin_lock_irq(&vkms_output->lock);
> +}
> +
>  static void vkms_crtc_atomic_flush(struct drm_crtc *crtc,
>  				   struct drm_crtc_state *old_crtc_state)
>  {
> +	struct vkms_output *vkms_output = drm_crtc_to_vkms_output(crtc);
>  	unsigned long flags;
>  
>  	if (crtc->state->event) {
> @@ -151,9 +183,12 @@ static void vkms_crtc_atomic_flush(struct drm_crtc *crtc,
>  
>  		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;
>  }
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
> index 37aa2ef33b21..5d78bd97e69c 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.c
> +++ b/drivers/gpu/drm/vkms/vkms_drv.c
> @@ -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 = {
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
> index aa2632ff5f06..9eb2d8eb1720 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.h
> +++ b/drivers/gpu/drm/vkms/vkms_drv.h
> @@ -20,19 +20,30 @@ static const u32 vkms_formats[] = {
>  	DRM_FORMAT_XRGB8888,
>  };
>  
> +struct vkms_crc_data {
> +	struct drm_rect src;
> +	struct drm_framebuffer fb;
> +};
> +
>  /* vkms_plane_state - Driver specific plane state
>   * @base: base plane state
> + * @crc_data: data required for CRC computation
>   */
>  struct vkms_plane_state {
>  	struct drm_plane_state base;
> +	struct vkms_crc_data *crc_data;
>  };
>  
>  /**
>   * vkms_crtc_state - Driver specific CRTC state
>   * @base: base CRTC state
> + * @crc_work: work struct to compute and add CRC entries
> + * @n_frame: frame number for computed CRC
>   */
>  struct vkms_crtc_state {
>  	struct drm_crtc_state base;
> +	struct work_struct crc_work;
> +	unsigned int n_frame;
>  };
>  
>  struct vkms_output {
> @@ -42,6 +53,12 @@ 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;
> +	struct vkms_crc_data *primary_crc;

It doesn't seem like we need this. Can't we just access crc_data from the
plane_state of the primary plane? This will be closer to the final solution
where we eventually need to provide crc data for all planes.

Sean


> +	/* protects concurrent access to crc_data */
> +	spinlock_t lock;
>  };
>  
>  struct vkms_device {
> @@ -105,4 +122,9 @@ 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_ */
> diff --git a/drivers/gpu/drm/vkms/vkms_plane.c b/drivers/gpu/drm/vkms/vkms_plane.c
> index 70fca22bc51b..c2e783c6e626 100644
> --- a/drivers/gpu/drm/vkms/vkms_plane.c
> +++ b/drivers/gpu/drm/vkms/vkms_plane.c
> @@ -16,11 +16,18 @@ static struct drm_plane_state *
>  vkms_plane_duplicate_state(struct drm_plane *plane)
>  {
>  	struct vkms_plane_state *vkms_state;
> +	struct vkms_crc_data *crc_data;
>  
>  	vkms_state = kzalloc(sizeof(*vkms_state), GFP_KERNEL);
>  	if (!vkms_state)
>  		return NULL;
>  
> +	crc_data = kzalloc(sizeof(*crc_data), GFP_KERNEL);
> +	if (WARN_ON(!crc_data))
> +		DRM_INFO("Couldn't allocate crc_data");
> +
> +	vkms_state->crc_data = crc_data;
> +
>  	__drm_atomic_helper_plane_duplicate_state(plane,
>  						  &vkms_state->base);
>  
> @@ -31,6 +38,27 @@ static void vkms_plane_destroy_state(struct drm_plane *plane,
>  				     struct drm_plane_state *old_state)
>  {
>  	struct vkms_plane_state *vkms_state = to_vkms_plane_state(old_state);
> +	struct drm_crtc *crtc = vkms_state->base.crtc;
> +
> +	if (crtc) {
> +		struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
> +		unsigned long flags;
> +
> +		if (plane->type == DRM_PLANE_TYPE_PRIMARY) {
> +			spin_lock_irqsave(&out->lock, flags);
> +			out->primary_crc = NULL;
> +			spin_unlock_irqrestore(&out->lock, flags);
> +		}
> +
> +		/* dropping the reference we acquired in
> +		 * vkms_primary_plane_update()
> +		 */
> +		if (drm_framebuffer_read_refcount(&vkms_state->crc_data->fb))
> +			drm_framebuffer_put(&vkms_state->crc_data->fb);
> +	}
> +
> +	kfree(vkms_state->crc_data);
> +	vkms_state->crc_data = NULL;
>  
>  	__drm_atomic_helper_plane_destroy_state(old_state);
>  	kfree(vkms_state);
> @@ -65,6 +93,22 @@ 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)
>  {
> +	struct vkms_plane_state *vkms_plane_state;
> +	struct vkms_crc_data *crc_data;
> +	struct vkms_output *out;
> +
> +	if (!plane->state->crtc || !plane->state->fb)
> +		return;
> +
> +	vkms_plane_state = to_vkms_plane_state(plane->state);
> +	crc_data = vkms_plane_state->crc_data;
> +	memcpy(&crc_data->src, &plane->state->src, sizeof(struct drm_rect));
> +	memcpy(&crc_data->fb, plane->state->fb, sizeof(struct drm_framebuffer));
> +	drm_framebuffer_get(&crc_data->fb);
> +
> +	out = drm_crtc_to_vkms_output(plane->state->crtc);
> +	if (plane->type == DRM_PLANE_TYPE_PRIMARY)
> +		out->primary_crc = crc_data;
>  }
>  
>  static int vkms_plane_atomic_check(struct drm_plane *plane,
> -- 
> 2.17.1
>
diff mbox series

Patch

diff --git a/drivers/gpu/drm/vkms/Makefile b/drivers/gpu/drm/vkms/Makefile
index 986297da51bf..37966914f70b 100644
--- a/drivers/gpu/drm/vkms/Makefile
+++ b/drivers/gpu/drm/vkms/Makefile
@@ -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
diff --git a/drivers/gpu/drm/vkms/vkms_crc.c b/drivers/gpu/drm/vkms/vkms_crc.c
new file mode 100644
index 000000000000..d4f94ac932a7
--- /dev/null
+++ b/drivers/gpu/drm/vkms/vkms_crc.c
@@ -0,0 +1,75 @@ 
+// 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);
+	u32 crc = 0;
+	int i = 0;
+	unsigned int x = crc_data->src.x1 >> 16;
+	unsigned int y = crc_data->src.y1 >> 16;
+	unsigned int height = drm_rect_height(&crc_data->src) >> 16;
+	unsigned int width = drm_rect_width(&crc_data->src) >> 16;
+	unsigned int cpp = fb->format->cpp[0];
+	unsigned int src_offset;
+	unsigned int size_byte = width * cpp;
+	void *vaddr;
+
+	mutex_lock(&vkms_obj->pages_lock);
+	vaddr = vkms_obj->vaddr;
+	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);
+	}
+	mutex_unlock(&vkms_obj->pages_lock);
+
+	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) {
+		unsigned int n_frame = crtc_state->n_frame;
+		u32 crc32 = 0;
+
+		if (out->primary_crc)
+			crc32 = _vkms_get_crc(out->primary_crc);
+
+		drm_crtc_add_crc_entry(crtc, true, n_frame, &crc32);
+	}
+}
+
+int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name,
+			size_t *values_cnt)
+{
+	struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
+	bool enabled = false;
+	unsigned long flags;
+	int ret = 0;
+
+	if (src_name && strcmp(src_name, "auto") == 0)
+		enabled = true;
+	else if (src_name)
+		ret = -EINVAL;
+
+	*values_cnt = 1;
+
+	spin_lock_irqsave(&out->lock, flags);
+	out->crc_enabled = enabled;
+	spin_unlock_irqrestore(&out->lock, flags);
+
+	return ret;
+}
diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
index 26babb85ca77..a6c080d7f7ae 100644
--- a/drivers/gpu/drm/vkms/vkms_crtc.c
+++ b/drivers/gpu/drm/vkms/vkms_crtc.c
@@ -10,18 +10,33 @@ 
 #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");
 
+	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);
 
@@ -97,18 +112,22 @@  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;
 }
 
 static void vkms_atomic_crtc_destroy_state(struct drm_crtc *crtc,
 					   struct drm_crtc_state *state)
 {
-	struct vkms_crtc_state *vkms_state;
-
-	vkms_state = to_vkms_crtc_state(state);
+	struct vkms_crtc_state *vkms_state = to_vkms_crtc_state(state);
 
 	__drm_atomic_helper_crtc_destroy_state(state);
-	kfree(vkms_state);
+
+	if (vkms_state) {
+		flush_work(&vkms_state->crc_work);
+		kfree(vkms_state);
+	}
 }
 
 static const struct drm_crtc_funcs vkms_crtc_funcs = {
@@ -120,6 +139,7 @@  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,
@@ -134,9 +154,21 @@  static void vkms_crtc_atomic_disable(struct drm_crtc *crtc,
 	drm_crtc_vblank_off(crtc);
 }
 
+static void vkms_crtc_atomic_begin(struct drm_crtc *crtc,
+				   struct drm_crtc_state *old_crtc_state)
+{
+	struct vkms_output *vkms_output = drm_crtc_to_vkms_output(crtc);
+
+	/* This lock is held across the atomic commit to block vblamk timer
+	 * from scheduling vkms_crc_work_handle until the crc_data is updated
+	 */
+	spin_lock_irq(&vkms_output->lock);
+}
+
 static void vkms_crtc_atomic_flush(struct drm_crtc *crtc,
 				   struct drm_crtc_state *old_crtc_state)
 {
+	struct vkms_output *vkms_output = drm_crtc_to_vkms_output(crtc);
 	unsigned long flags;
 
 	if (crtc->state->event) {
@@ -151,9 +183,12 @@  static void vkms_crtc_atomic_flush(struct drm_crtc *crtc,
 
 		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;
 }
diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
index 37aa2ef33b21..5d78bd97e69c 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.c
+++ b/drivers/gpu/drm/vkms/vkms_drv.c
@@ -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 = {
diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
index aa2632ff5f06..9eb2d8eb1720 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -20,19 +20,30 @@  static const u32 vkms_formats[] = {
 	DRM_FORMAT_XRGB8888,
 };
 
+struct vkms_crc_data {
+	struct drm_rect src;
+	struct drm_framebuffer fb;
+};
+
 /* vkms_plane_state - Driver specific plane state
  * @base: base plane state
+ * @crc_data: data required for CRC computation
  */
 struct vkms_plane_state {
 	struct drm_plane_state base;
+	struct vkms_crc_data *crc_data;
 };
 
 /**
  * vkms_crtc_state - Driver specific CRTC state
  * @base: base CRTC state
+ * @crc_work: work struct to compute and add CRC entries
+ * @n_frame: frame number for computed CRC
  */
 struct vkms_crtc_state {
 	struct drm_crtc_state base;
+	struct work_struct crc_work;
+	unsigned int n_frame;
 };
 
 struct vkms_output {
@@ -42,6 +53,12 @@  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;
+	struct vkms_crc_data *primary_crc;
+	/* protects concurrent access to crc_data */
+	spinlock_t lock;
 };
 
 struct vkms_device {
@@ -105,4 +122,9 @@  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_ */
diff --git a/drivers/gpu/drm/vkms/vkms_plane.c b/drivers/gpu/drm/vkms/vkms_plane.c
index 70fca22bc51b..c2e783c6e626 100644
--- a/drivers/gpu/drm/vkms/vkms_plane.c
+++ b/drivers/gpu/drm/vkms/vkms_plane.c
@@ -16,11 +16,18 @@  static struct drm_plane_state *
 vkms_plane_duplicate_state(struct drm_plane *plane)
 {
 	struct vkms_plane_state *vkms_state;
+	struct vkms_crc_data *crc_data;
 
 	vkms_state = kzalloc(sizeof(*vkms_state), GFP_KERNEL);
 	if (!vkms_state)
 		return NULL;
 
+	crc_data = kzalloc(sizeof(*crc_data), GFP_KERNEL);
+	if (WARN_ON(!crc_data))
+		DRM_INFO("Couldn't allocate crc_data");
+
+	vkms_state->crc_data = crc_data;
+
 	__drm_atomic_helper_plane_duplicate_state(plane,
 						  &vkms_state->base);
 
@@ -31,6 +38,27 @@  static void vkms_plane_destroy_state(struct drm_plane *plane,
 				     struct drm_plane_state *old_state)
 {
 	struct vkms_plane_state *vkms_state = to_vkms_plane_state(old_state);
+	struct drm_crtc *crtc = vkms_state->base.crtc;
+
+	if (crtc) {
+		struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
+		unsigned long flags;
+
+		if (plane->type == DRM_PLANE_TYPE_PRIMARY) {
+			spin_lock_irqsave(&out->lock, flags);
+			out->primary_crc = NULL;
+			spin_unlock_irqrestore(&out->lock, flags);
+		}
+
+		/* dropping the reference we acquired in
+		 * vkms_primary_plane_update()
+		 */
+		if (drm_framebuffer_read_refcount(&vkms_state->crc_data->fb))
+			drm_framebuffer_put(&vkms_state->crc_data->fb);
+	}
+
+	kfree(vkms_state->crc_data);
+	vkms_state->crc_data = NULL;
 
 	__drm_atomic_helper_plane_destroy_state(old_state);
 	kfree(vkms_state);
@@ -65,6 +93,22 @@  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)
 {
+	struct vkms_plane_state *vkms_plane_state;
+	struct vkms_crc_data *crc_data;
+	struct vkms_output *out;
+
+	if (!plane->state->crtc || !plane->state->fb)
+		return;
+
+	vkms_plane_state = to_vkms_plane_state(plane->state);
+	crc_data = vkms_plane_state->crc_data;
+	memcpy(&crc_data->src, &plane->state->src, sizeof(struct drm_rect));
+	memcpy(&crc_data->fb, plane->state->fb, sizeof(struct drm_framebuffer));
+	drm_framebuffer_get(&crc_data->fb);
+
+	out = drm_crtc_to_vkms_output(plane->state->crtc);
+	if (plane->type == DRM_PLANE_TYPE_PRIMARY)
+		out->primary_crc = crc_data;
 }
 
 static int vkms_plane_atomic_check(struct drm_plane *plane,