Hi Sam,
Thank you for the patch.
On Sat, Dec 07, 2019 at 03:03:29PM +0100, Sam Ravnborg wrote:
> The callbacks in drm_panel_funcs are optional, so do not
> return an error just because no callback is assigned.
>
> v2:
> - Document what functions in drm_panel_funcs are optional (Laurent)
> - Return -EOPNOTSUPP if get_modes() is not assigned (Laurent)
> (Sam: -EOPNOTSUPP seems to best error code in this situation)
>
> Signed-off-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: Maxime Ripard <mripard@xxxxxxxxxx>
> Cc: Thierry Reding <thierry.reding@xxxxxxxxx>
> Cc: Sam Ravnborg <sam@xxxxxxxxxxxx>
> Cc: David Airlie <airlied@xxxxxxxx>
> Cc: Daniel Vetter <daniel@xxxxxxxx>
> ---
> drivers/gpu/drm/drm_panel.c | 35 +++++++++++++++++++++++++----------
> include/drm/drm_panel.h | 18 ++++++++++++++++--
> 2 files changed, 41 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
> index ed7985c0535a..4ab7229fb22b 100644
> --- a/drivers/gpu/drm/drm_panel.c
> +++ b/drivers/gpu/drm/drm_panel.c
> @@ -151,10 +151,13 @@ EXPORT_SYMBOL(drm_panel_detach);
> */
> int drm_panel_prepare(struct drm_panel *panel)
> {
> - if (panel && panel->funcs && panel->funcs->prepare)
> + if (!panel)
> + return -EINVAL;
> +
> + if (panel->funcs && panel->funcs->prepare)
> return panel->funcs->prepare(panel);
>
> - return panel ? -ENOSYS : -EINVAL;
> + return 0;
> }
> EXPORT_SYMBOL(drm_panel_prepare);
>
> @@ -171,10 +174,13 @@ EXPORT_SYMBOL(drm_panel_prepare);
> */
> int drm_panel_unprepare(struct drm_panel *panel)
> {
> - if (panel && panel->funcs && panel->funcs->unprepare)
> + if (!panel)
> + return -EINVAL;
> +
> + if (panel->funcs && panel->funcs->unprepare)
> return panel->funcs->unprepare(panel);
>
> - return panel ? -ENOSYS : -EINVAL;
> + return 0;
> }
> EXPORT_SYMBOL(drm_panel_unprepare);
>
> @@ -190,10 +196,13 @@ EXPORT_SYMBOL(drm_panel_unprepare);
> */
> int drm_panel_enable(struct drm_panel *panel)
> {
> - if (panel && panel->funcs && panel->funcs->enable)
> + if (!panel)
> + return -EINVAL;
> +
> + if (panel->funcs && panel->funcs->enable)
> return panel->funcs->enable(panel);
>
> - return panel ? -ENOSYS : -EINVAL;
> + return 0;
> }
> EXPORT_SYMBOL(drm_panel_enable);
>
> @@ -209,10 +218,13 @@ EXPORT_SYMBOL(drm_panel_enable);
> */
> int drm_panel_disable(struct drm_panel *panel)
> {
> - if (panel && panel->funcs && panel->funcs->disable)
> + if (!panel)
> + return -EINVAL;
> +
> + if (panel->funcs && panel->funcs->disable)
> return panel->funcs->disable(panel);
>
> - return panel ? -ENOSYS : -EINVAL;
> + return 0;
> }
> EXPORT_SYMBOL(drm_panel_disable);
>
> @@ -228,10 +240,13 @@ EXPORT_SYMBOL(drm_panel_disable);
> */
> int drm_panel_get_modes(struct drm_panel *panel)
> {
> - if (panel && panel->funcs && panel->funcs->get_modes)
> + if (!panel)
> + return -EINVAL;
> +
> + if (panel->funcs && panel->funcs->get_modes)
> return panel->funcs->get_modes(panel);
>
> - return panel ? -ENOSYS : -EINVAL;
> + return -EOPNOTSUPP;
> }
> EXPORT_SYMBOL(drm_panel_get_modes);
>
> diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h
> index ce8da64022b4..d71655b2634c 100644
> --- a/include/drm/drm_panel.h
> +++ b/include/drm/drm_panel.h
> @@ -65,6 +65,8 @@ struct drm_panel_funcs {
> * @prepare:
> *
> * Turn on panel and perform set up.
> + *
> + * This function is optional.
> */
> int (*prepare)(struct drm_panel *panel);
>
> @@ -72,6 +74,8 @@ struct drm_panel_funcs {
> * @enable:
> *
> * Enable panel (turn on back light, etc.).
> + *
> + * This function is optional.
> */
> int (*enable)(struct drm_panel *panel);
>
> @@ -79,6 +83,8 @@ struct drm_panel_funcs {
> * @disable:
> *
> * Disable panel (turn off back light, etc.).
> + *
> + * This function is optional.
> */
> int (*disable)(struct drm_panel *panel);
>
> @@ -86,14 +92,20 @@ struct drm_panel_funcs {
> * @unprepare:
> *
> * Turn off panel.
> + *
> + * This function is optional.
> */
> int (*unprepare)(struct drm_panel *panel);
>
> /**
> * @get_modes:
> *
> - * Add modes to the connector that the panel is attached to and
> - * return the number of modes added.
> + * Add modes to the connector that the panel is attached to.
> + *
> + * This function is mandatory.
> + *
> + * Returns the number of modes added, -EOPNOTSUPP if callback
> + * is missing, -EINVAL if panel is NULL.
This applies to drm_panel_get_modes, not &drm_panel_funcs.get_modes.
Here you should just have
*
* Add modes to the connector that the panel is attached to and
* return the number of modes added.
+ *
+ * This function is mandatory.
*/
int (*get_modes)(struct drm_panel *panel);
> */
> int (*get_modes)(struct drm_panel *panel);
>
> @@ -102,6 +114,8 @@ struct drm_panel_funcs {
> *
> * Copy display timings into the provided array and return
> * the number of display timings available.
> + *
> + * This function is optional.
> */
> int (*get_timings)(struct drm_panel *panel, unsigned int num_timings,
> struct display_timing *timings);
--
Regards,
Laurent Pinchart
