Thomas Zimmermann <tzimmermann@xxxxxxx> writes:
Hello Thomas,
Thanks for your patch.
> The plane's atomic_check returns -EINVAL if the CRTC has not been
> set. This is the case for disabled planes, for which atomic_check
> should return 0. For disabled planes, it also omits the mandatory
> call to drm_atomic_helper_check_plane_state().
>
> Replace the test with the boiler-plate code that first invokes
> drm_atomic_helper_check_plane_state() and then tests for the plane
> to be visible. Return early for non-visible planes.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Fixes: d51f9fbd98b6 ("drm/ssd130x: Store the HW buffer in the driver-private CRTC state")
> Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> Cc: Javier Martinez Canillas <javierm@xxxxxxxxxx>
> Cc: Maxime Ripard <mripard@xxxxxxxxxx>
> ---
> drivers/gpu/drm/solomon/ssd130x.c | 17 +++++++++--------
> 1 file changed, 9 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
> index 3dd8e8a444b6f..dccbfe33edb5e 100644
> --- a/drivers/gpu/drm/solomon/ssd130x.c
> +++ b/drivers/gpu/drm/solomon/ssd130x.c
> @@ -639,21 +639,22 @@ static int ssd130x_primary_plane_atomic_check(struct drm_plane *plane,
> struct drm_plane_state *plane_state = drm_atomic_get_new_plane_state(state, plane);
> struct ssd130x_plane_state *ssd130x_state = to_ssd130x_plane_state(plane_state);
> struct drm_crtc *crtc = plane_state->crtc;
> - struct drm_crtc_state *crtc_state;
> + struct drm_crtc_state *crtc_state = NULL;
> const struct drm_format_info *fi;
> unsigned int pitch;
> int ret;
>
> - if (!crtc)
> - return -EINVAL;
> -
> - crtc_state = drm_atomic_get_crtc_state(state, crtc);
> - if (IS_ERR(crtc_state))
> - return PTR_ERR(crtc_state);
> + if (crtc)
> + crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
>
> - ret = drm_plane_helper_atomic_check(plane, state);
> + ret = drm_atomic_helper_check_plane_state(plane_state, crtc_state,
> + DRM_PLANE_NO_SCALING,
> + DRM_PLANE_NO_SCALING,
> + false, false);
As Geert mentioned you are open coding here what the called helper already
does. I prefer to keep doing that, instead of adding boiler plate code.
One question, the reason to return -EINVAL was to prevent the callback
ssd130x_primary_plane_atomic_update() to be executed, since that attempts
to get the CRTC state to pass the HW buffer to ssd130x_fb_blit_rect().
I believe this patch will introduce a regression and cause a NULL pointer
dereference when !plane_state->crtc and you should also add a check for
plane_state->visible in ssd130x_primary_plane_atomic_update() to bail ?
I haven't tested your patch yet though, so maybe I'm wrong about this.
--
Best regards,
Javier Martinez Canillas
Core Platforms
Red Hat
