On Wed, Apr 23, 2014 at 10:30:05AM +0200, Daniel Vetter wrote:
> The ->disable_plane hook always had a return value, but only since the
> introduction of primary planes was there any implementation that
> actually failed.
>
> So handle such failures correctly.
>
> Note that drm_plane_force_disable is special: In the modeset cleanup
> case we first disable all crtc, so primary planes should all be freed
> already. And in the fb helper we only reset non-primary planes. Still
> better be paranoid and add an early return.
>
> I don't see how this could happen, but it might fix the fb refcount
> underrun Thierry is seeing. Matt Roper spotted this issue.
>
> Cc: Thierry Reding <treding@xxxxxxxxxx>
> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Cc: Matt Roper <matthew.d.roper@xxxxxxxxx>
> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
Reviewed-by: Matt Roper <matthew.d.roper@xxxxxxxxx>
> ---
> drivers/gpu/drm/drm_crtc.c | 14 ++++++++++----
> 1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index f6633cb927bc..461d19bd14ee 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -1152,8 +1152,10 @@ void drm_plane_force_disable(struct drm_plane *plane)
> return;
>
> ret = plane->funcs->disable_plane(plane);
> - if (ret)
> + if (ret) {
> DRM_ERROR("failed to disable plane with busy fb\n");
> + return;
> + }
> /* disconnect the plane from the fb and crtc: */
> __drm_framebuffer_unreference(old_fb);
> plane->fb = NULL;
> @@ -2117,9 +2119,13 @@ int drm_mode_setplane(struct drm_device *dev, void *data,
> if (!plane_req->fb_id) {
> drm_modeset_lock_all(dev);
> old_fb = plane->fb;
> - plane->funcs->disable_plane(plane);
> - plane->crtc = NULL;
> - plane->fb = NULL;
> + ret = plane->funcs->disable_plane(plane);
> + if (!ret) {
> + plane->crtc = NULL;
> + plane->fb = NULL;
> + } else {
> + old_fb = NULL;
> + }
> drm_modeset_unlock_all(dev);
> goto out;
> }
> --
> 1.9.2
>
--
Matt Roper
Graphics Software Engineer
IoTG Platform Enabling & Development
Intel Corporation
(916) 356-2795
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