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

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