Re: [PATCH V4 1/3] drm/vkms: Decouple crc operations from composer

Hi Rodrigo,

On Mon, 11 May 2020 at 12:55, Rodrigo Siqueira Rodrigo.Siqueira@amd.com wrote:

-static uint32_t _vkms_get_crc(struct vkms_composer *primary_composer,

•                         struct vkms_composer *cursor_composer)
  

+static int compose_planes(void **vaddr_out,

•                     struct vkms_composer *primary_composer,
  

•                     struct vkms_composer *cursor_composer)
  

{ struct drm_framebuffer *fb = &primary_composer->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);

•   void *vaddr_out = kzalloc(vkms_obj->gem.size, GFP_KERNEL);
  

•   u32 crc = 0;
  
  

•   if (!vaddr_out) {
  

•           DRM_ERROR("Failed to allocate memory for output frame.");
  

•           return 0;
  

•   if (!*vaddr_out) {
  

•           *vaddr_out = kzalloc(vkms_obj->gem.size, GFP_KERNEL);
  

It would be clearer if you keep the to alloc (or not for wb) in the caller. As-is it's very subtle and error prone.

•           if (!*vaddr_out) {
  

•                   DRM_ERROR("Cannot allocate memory for output frame.");
  

•                   return -ENOMEM;
  

•           }
    }
  
  

•   if (WARN_ON(!vkms_obj->vaddr)) {
  

•           kfree(vaddr_out);
  

•           return crc;
  

•   }
  

•   if (WARN_ON(!vkms_obj->vaddr))
  

•           return -EINVAL;
  
  

•   memcpy(vaddr_out, vkms_obj->vaddr, vkms_obj->gem.size);
  

•   memcpy(*vaddr_out, vkms_obj->vaddr, vkms_obj->gem.size);
  
    if (cursor_composer)
  

•           compose_cursor(cursor_composer, primary_composer, vaddr_out);
  

•           compose_cursor(cursor_composer, primary_composer, *vaddr_out);
  
  

•   crc = compute_crc(vaddr_out, primary_composer);
  

•   kfree(vaddr_out);
  

•   return crc;
  

•   return 0;
  

}

/** @@ -157,9 +153,11 @@ void vkms_composer_worker(struct work_struct *work) struct vkms_output *out = drm_crtc_to_vkms_output(crtc); struct vkms_composer *primary_composer = NULL; struct vkms_composer *cursor_composer = NULL;

•   void *vaddr_out = NULL;
    u32 crc32 = 0;
    u64 frame_start, frame_end;
    bool crc_pending;
  

•   int ret;
  
    spin_lock_irq(&out->composer_lock);
    frame_start = crtc_state->frame_start;
  

@@ -183,14 +181,25 @@ void vkms_composer_worker(struct work_struct *work) if (crtc_state->num_active_planes == 2) cursor_composer = crtc_state->active_planes[1]->composer;

•   if (primary_composer)
  

•           crc32 = _vkms_get_crc(primary_composer, cursor_composer);
  

•   if (!primary_composer)
  

•           return;
  

This early return changes the functionality. Namely the drm_crtc_add_crc_entry(.... 0) is now missing. I don't recall much about the crc to judge if that's a genuine bugfix, or newly introduced bug.

In the former case, it should be a separate patch.

•   ret = compose_planes(&vaddr_out, primary_composer, cursor_composer);
  

•   if (ret) {
  

•           if (ret == -EINVAL)
  

•                   kfree(vaddr_out);
  

•           return;
  

•   }
  

•   crc32 = compute_crc(vaddr_out, primary_composer);
  
    /*
     * The worker can fall behind the vblank hrtimer, make sure we catch up.
     */
    while (frame_start <= frame_end)
            drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32);
  

•   kfree(vaddr_out);
  

Nit: move the free() just after compute_crc() - it's not needed for the drm_crtc_add_crc_entry().

-Emil