Re: [PATCH v2 4/8] drm: vkms: Add fb information to `vkms_writeback_job`

[Igor Torrente <igormtorrente@xxxxxxxxx>]

Hi Thomas,

On 11/3/21 12:45 PM, Thomas Zimmermann wrote:
> Hi
>
> Am 26.10.21 um 13:34 schrieb Igor Torrente:
> > This commit is the groundwork to introduce new formats to the planes and
> > writeback buffer. As part of it, a new buffer metadata field is added to
> > `vkms_writeback_job`, this metadata is represented by the `vkms_composer`
> > struct.
> >
> > This will allow us, in the future, to have different compositing and wb
> > format types.
> >
> > Signed-off-by: Igor Torrente <igormtorrente@xxxxxxxxx>
> > ---
> > V2: Change the code to get the drm_framebuffer reference and not copy its
> >       contents(Thomas Zimmermann).
> > ---
> >    drivers/gpu/drm/vkms/vkms_composer.c  |  4 ++--
> >    drivers/gpu/drm/vkms/vkms_drv.h       | 12 ++++++------
> >    drivers/gpu/drm/vkms/vkms_plane.c     | 10 +++++-----
> >    drivers/gpu/drm/vkms/vkms_writeback.c | 21 ++++++++++++++++++---
> >    4 files changed, 31 insertions(+), 16 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
> > index 82f79e508f81..383ca657ddf7 100644
> > --- a/drivers/gpu/drm/vkms/vkms_composer.c
> > +++ b/drivers/gpu/drm/vkms/vkms_composer.c
> > @@ -153,7 +153,7 @@ static void compose_plane(struct vkms_composer *primary_composer,
> >    			  struct vkms_composer *plane_composer,
> >    			  void *vaddr_out)
> >    {
> > -	struct drm_framebuffer *fb = &plane_composer->fb;
> > +	struct drm_framebuffer *fb = plane_composer->fb;
> >    	void *vaddr;
> >    	void (*pixel_blend)(const u8 *p_src, u8 *p_dst);
> >    
> > @@ -174,7 +174,7 @@ static int compose_active_planes(void **vaddr_out,
> >    				 struct vkms_composer *primary_composer,
> >    				 struct vkms_crtc_state *crtc_state)
> >    {
> > -	struct drm_framebuffer *fb = &primary_composer->fb;
> > +	struct drm_framebuffer *fb = primary_composer->fb;
> >    	struct drm_gem_object *gem_obj = drm_gem_fb_get_obj(fb, 0);
> >    	const void *vaddr;
> >    	int i;
> > diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
> > index 64e62993b06f..9e4c1e95bbb1 100644
> > --- a/drivers/gpu/drm/vkms/vkms_drv.h
> > +++ b/drivers/gpu/drm/vkms/vkms_drv.h
> > @@ -20,13 +20,8 @@
> >    #define XRES_MAX  8192
> >    #define YRES_MAX  8192
> >    
> > -struct vkms_writeback_job {
> > -	struct dma_buf_map map[DRM_FORMAT_MAX_PLANES];
> > -	struct dma_buf_map data[DRM_FORMAT_MAX_PLANES];
> > -};
> > -
> >    struct vkms_composer {
> > -	struct drm_framebuffer fb;
> > +	struct drm_framebuffer *fb;
> >    	struct drm_rect src, dst;
> >    	struct dma_buf_map map[DRM_FORMAT_MAX_PLANES];
> >    	unsigned int offset;
> > @@ -34,6 +29,11 @@ struct vkms_composer {
> >    	unsigned int cpp;
> >    };
> >    
> > +struct vkms_writeback_job {
> > +	struct dma_buf_map data[DRM_FORMAT_MAX_PLANES];
> > +	struct vkms_composer composer;
> > +};
> > +
> >    /**
> >     * vkms_plane_state - Driver specific plane state
> >     * @base: base plane state
> > diff --git a/drivers/gpu/drm/vkms/vkms_plane.c b/drivers/gpu/drm/vkms/vkms_plane.c
> > index 32409e15244b..0a28cb7a85e2 100644
> > --- a/drivers/gpu/drm/vkms/vkms_plane.c
> > +++ b/drivers/gpu/drm/vkms/vkms_plane.c
> > @@ -50,12 +50,12 @@ static void vkms_plane_destroy_state(struct drm_plane *plane,
> >    	struct vkms_plane_state *vkms_state = to_vkms_plane_state(old_state);
> >    	struct drm_crtc *crtc = vkms_state->base.base.crtc;
> >    
> > -	if (crtc) {
> > +	if (crtc && vkms_state->composer->fb) {
> >    		/* dropping the reference we acquired in
> >    		 * vkms_primary_plane_update()
> >    		 */
> > -		if (drm_framebuffer_read_refcount(&vkms_state->composer->fb))
> > -			drm_framebuffer_put(&vkms_state->composer->fb);
> > +		if (drm_framebuffer_read_refcount(vkms_state->composer->fb))
> > +			drm_framebuffer_put(vkms_state->composer->fb);
> >    	}
> >    
> >    	kfree(vkms_state->composer);
> > @@ -110,9 +110,9 @@ static void vkms_plane_atomic_update(struct drm_plane *plane,
> >    	composer = vkms_plane_state->composer;
> >    	memcpy(&composer->src, &new_state->src, sizeof(struct drm_rect));
> >    	memcpy(&composer->dst, &new_state->dst, sizeof(struct drm_rect));
> > -	memcpy(&composer->fb, fb, sizeof(struct drm_framebuffer));
> > +	composer->fb = fb;
> >    	memcpy(&composer->map, &shadow_plane_state->data, sizeof(composer->map));
> > -	drm_framebuffer_get(&composer->fb);
> > +	drm_framebuffer_get(composer->fb);
> >    	composer->offset = fb->offsets[0];
> >    	composer->pitch = fb->pitches[0];
> >    	composer->cpp = fb->format->cpp[0];
> > diff --git a/drivers/gpu/drm/vkms/vkms_writeback.c b/drivers/gpu/drm/vkms/vkms_writeback.c
> > index 8694227f555f..32734cdbf6c2 100644
> > --- a/drivers/gpu/drm/vkms/vkms_writeback.c
> > +++ b/drivers/gpu/drm/vkms/vkms_writeback.c
> > @@ -75,12 +75,15 @@ static int vkms_wb_prepare_job(struct drm_writeback_connector *wb_connector,
> >    	if (!vkmsjob)
> >    		return -ENOMEM;
> >    
> > -	ret = drm_gem_fb_vmap(job->fb, vkmsjob->map, vkmsjob->data);
> > +	ret = drm_gem_fb_vmap(job->fb, vkmsjob->composer.map, vkmsjob->data);
> >    	if (ret) {
> >    		DRM_ERROR("vmap failed: %d\n", ret);
> >    		goto err_kfree;
> >    	}
> >    
> > +	vkmsjob->composer.fb = job->fb;
> > +	drm_framebuffer_get(vkmsjob->composer.fb);
> > +
> >    	job->priv = vkmsjob;
> >    
> >    	return 0;
> > @@ -99,7 +102,10 @@ static void vkms_wb_cleanup_job(struct drm_writeback_connector *connector,
> >    	if (!job->fb)
> >    		return;
> >    
> > -	drm_gem_fb_vunmap(job->fb, vkmsjob->map);
> > +	drm_gem_fb_vunmap(job->fb, vkmsjob->composer.map);
> > +
> > +	if (drm_framebuffer_read_refcount(vkmsjob->composer.fb))
> > +		drm_framebuffer_put(vkmsjob->composer.fb);
>
> Why is this protected by an if conditional?

Here, I followed what was done in the vkms_plane code, just adapting it
to the writeback callbacks.

I put this if because I wasn't 100% sure that for each
`vkms_wb_prepare_job` I would have exactly one `vkms_wb_cleanup_job`
after it.

It happened in my testings, but I can't guarantee that it will always
happen.

> Best regards
> Thomas
>
> >    
> >    	vkmsdev = drm_device_to_vkms_device(job->fb->dev);
> >    	vkms_set_composer(&vkmsdev->output, false);
> > @@ -116,14 +122,23 @@ static void vkms_wb_atomic_commit(struct drm_connector *conn,
> >    	struct drm_writeback_connector *wb_conn = &output->wb_connector;
> >    	struct drm_connector_state *conn_state = wb_conn->base.state;
> >    	struct vkms_crtc_state *crtc_state = output->composer_state;
> > +	struct drm_framebuffer *fb = connector_state->writeback_job->fb;
> > +	struct vkms_writeback_job *active_wb;
> > +	struct vkms_composer *wb_composer;
> >    
> >    	if (!conn_state)
> >    		return;
> >    
> >    	vkms_set_composer(&vkmsdev->output, true);
> >    
> > +	active_wb = conn_state->writeback_job->priv;
> > +	wb_composer = &active_wb->composer;
> > +
> >    	spin_lock_irq(&output->composer_lock);
> > -	crtc_state->active_writeback = conn_state->writeback_job->priv;
> > +	crtc_state->active_writeback = active_wb;
> > +	wb_composer->offset = fb->offsets[0];
> > +	wb_composer->pitch = fb->pitches[0];
> > +	wb_composer->cpp = fb->format->cpp[0];
> >    	crtc_state->wb_pending = true;
> >    	spin_unlock_irq(&output->composer_lock);
> >    	drm_writeback_queue_job(wb_conn, connector_state);

Thanks,
---
Igor M. A. Torrente