[PATCH 2/2] drm/vkms: Implement CRC debugfs API
Sean Paul
seanpaul at chromium.org
Tue Jul 31 18:01:27 UTC 2018
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 at 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
>
--
Sean Paul, Software Engineer, Google / Chromium OS
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