Re: [PATCH v3 5/5] drm/vkms: Implement CRC debugfs API

On Thu, Jul 19, 2018 at 03:22:16AM +0300, Haneen Mohammed wrote:

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 hamohammed.sa@gmail.com

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

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..9e8bb5c7fc80 --- /dev/null +++ b/drivers/gpu/drm/vkms/vkms_crc.c @@ -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);
• 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 = vkms_obj->vaddr;

You should hold the lock when copying the data from crc_data.

• 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;
  

• 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);

You should hold the lock when changing this value.

• 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;

+} diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c index 26babb85ca77..a7b39627b581 100644 --- a/drivers/gpu/drm/vkms/vkms_crtc.c +++ b/drivers/gpu/drm/vkms/vkms_crtc.c @@ -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;

}

@@ -108,7 +125,13 @@ static void vkms_atomic_crtc_destroy_state(struct drm_crtc *crtc, 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);
  

• drm_framebuffer_put(&vkms_state->data.fb);
  

It'd be nice to leave a breadcrumb explaining where this reference is acquired. ie: /* dropping the reference we acquired in vkms_primary_plane_update() */

• 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, @@ -134,26 +158,37 @@ 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);
• spin_lock_irq(&vkms_output->lock);

Can you please add a comment explaining that we're holding this across the commit to block the vblank timer, and why.

+}

static void vkms_crtc_atomic_flush(struct drm_crtc *crtc, struct drm_crtc_state *old_crtc_state) {

• unsigned long flags;

• struct vkms_output *vkms_output = drm_crtc_to_vkms_output(crtc);

  if (crtc->state->event) {

• spin_lock_irqsave(&crtc->dev->event_lock, flags);
  

• spin_lock(&crtc->dev->event_lock);
  

Either don't change this (since it's always safe to call _irqsave), or add a comment explaining why you don't need to.

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;

} 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 75e52d61e65d..a80281a12010 100644 --- a/drivers/gpu/drm/vkms/vkms_drv.h +++ b/drivers/gpu/drm/vkms/vkms_drv.h @@ -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_ */ diff --git a/drivers/gpu/drm/vkms/vkms_plane.c b/drivers/gpu/drm/vkms/vkms_plane.c index 5b7c5d59f103..b316b2af88ee 100644 --- a/drivers/gpu/drm/vkms/vkms_plane.c +++ b/drivers/gpu/drm/vkms/vkms_plane.c @@ -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) {

• struct vkms_crtc_state *state;
• if (!plane->state->crtc || !plane->state->fb)

• return;
  

• state = to_vkms_crtc_state(plane->state->crtc->state);
• memcpy(&state->data.src, &plane->state->src, sizeof(struct drm_rect));
• memcpy(&state->data.fb, plane->state->fb,

•       sizeof(struct drm_framebuffer));
  

• drm_framebuffer_get(&state->data.fb);

Similarly to above, a comment explaining this is released in state_destroy would be helpful.

}

static int vkms_plane_atomic_check(struct drm_plane *plane,

2.17.1