On Wed, Nov 01, 2017 at 04:04:33PM +0100, Maarten Lankhorst wrote:
> This introduces a slight behavioral change to rmfb. Instead of
> disabling a crtc when the primary plane is disabled, we try to
> preserve it.
> 
> Apart from old versions of the vmwgfx xorg driver, there is
> nothing depending on rmfb disabling a crtc.
> 
> Vmwgfx' and simple kms helper atomic implementation rejects CRTC
> enabled without plane, so we can do this safely.
> 
> If the atomic commit is rejected by the driver then we will still
> fall back to the old behavior and turn off the crtc.
> 
> Changes since v1:
> - Restart completely when rmfb with crtc on fails (Sean Paul).
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankho...@linux.intel.com>
> Cc: Sean Paul <seanp...@chromium.org>
> Cc: Daniel Vetter <daniel.vet...@ffwll.ch>
> ---
>  drivers/gpu/drm/drm_framebuffer.c | 23 +++++++++++++++++------
>  1 file changed, 17 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_framebuffer.c 
> b/drivers/gpu/drm/drm_framebuffer.c
> index 2affe53f3fda..f0679468f421 100644
> --- a/drivers/gpu/drm/drm_framebuffer.c
> +++ b/drivers/gpu/drm/drm_framebuffer.c
> @@ -765,14 +765,18 @@ static int atomic_remove_fb(struct drm_framebuffer *fb)
>       struct drm_plane *plane;
>       struct drm_connector *conn;
>       struct drm_connector_state *conn_state;
> -     int i, ret = 0;
> +     int i, ret;
>       unsigned plane_mask;
> +     bool disable_crtcs = false;
>  
> -     state = drm_atomic_state_alloc(dev);
> -     if (!state)
> -             return -ENOMEM;
> -
> +retry_disable:
>       drm_modeset_acquire_init(&ctx, 0);
> +
> +     state = drm_atomic_state_alloc(dev);
> +     if (!state) {
> +             ret = -ENOMEM;
> +             goto out;
> +     }
>       state->acquire_ctx = &ctx;
>  
>  retry:
> @@ -793,7 +797,7 @@ static int atomic_remove_fb(struct drm_framebuffer *fb)
>                       goto unlock;
>               }
>  
> -             if (plane_state->crtc->primary == plane) {
> +             if (disable_crtcs && plane_state->crtc->primary == plane) {
>                       struct drm_crtc_state *crtc_state;
>  
>                       crtc_state = drm_atomic_get_existing_crtc_state(state, 
> plane_state->crtc);
> @@ -818,6 +822,7 @@ static int atomic_remove_fb(struct drm_framebuffer *fb)
>               plane->old_fb = plane->fb;
>       }
>  
> +     /* This list is only filled when disable_crtcs is set. */
>       for_each_new_connector_in_state(state, conn, conn_state, i) {

WARN_ON(!disable_crtcs) maybe?

>               ret = drm_atomic_set_crtc_for_connector(conn_state, NULL);
>  
> @@ -840,9 +845,15 @@ static int atomic_remove_fb(struct drm_framebuffer *fb)
>  
>       drm_atomic_state_put(state);
>  
> +out:
>       drm_modeset_drop_locks(&ctx);
>       drm_modeset_acquire_fini(&ctx);
>  
> +     if (ret == -EINVAL && !disable_crtcs) {

Hmm. -EINVAL seems rather specific. Not sure if we could just check for
any error?

Or... I'm not sure if we have any central place where we do the
"can I disable the primary plane w/o disabling the crtc?" check. If we
do then we could also add a comment there informing people that the
-EINVAL is important.

> +             disable_crtcs = true;
> +             goto retry_disable;
> +     }
> +
>       return ret;
>  }
>  
> -- 
> 2.14.1
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Ville Syrjälä
Intel OTC
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