Hi Sam,
Thank you for the patch.
On Sun, Aug 04, 2019 at 10:16:35PM +0200, Sam Ravnborg wrote:
> Many panel drivers duplicate logic to prevent prepare to be called
> for a panel that is already prepared.
> Likewise for enable.
>
> Implement this logic in drm_panel so the individual drivers
> no longer needs this.
> A panel is considered prepared/enabled only if the prepare/enable call
> succeeds.
> For disable/unprepare it is unconditionally considered
> disabled/unprepared.
>
> This allows calls to prepare/enable again, even if there were
> some issue disabling a regulator or similar during disable/unprepare.
Is this the right place to handle this ? Shouldn't the upper layers
ensure than enable/disable and prepare/unprepare are correcty balanced,
and not called multiple times ? Adding enabled and prepared state to
drm_panel not only doesn't align well with atomic state handling, but
also would hide issues in upper layers that should really be fixed
there.
> Signed-off-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: Maxime Ripard <maxime.ripard@xxxxxxxxxxx>
> Cc: Sean Paul <sean@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 | 66 ++++++++++++++++++++++++++++++-------
> include/drm/drm_panel.h | 21 ++++++++++++
> 2 files changed, 75 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
> index da19d5b4a2f4..0853764040de 100644
> --- a/drivers/gpu/drm/drm_panel.c
> +++ b/drivers/gpu/drm/drm_panel.c
> @@ -66,10 +66,21 @@ EXPORT_SYMBOL(drm_panel_init);
> */
> int drm_panel_prepare(struct drm_panel *panel)
> {
> - if (panel && panel->funcs && panel->funcs->prepare)
> - return panel->funcs->prepare(panel);
> + int ret = -ENOSYS;
>
> - return panel ? -ENOSYS : -EINVAL;
> + if (!panel)
> + return -EINVAL;
> +
> + if (panel->prepared)
> + return 0;
> +
> + if (panel->funcs && panel->funcs->prepare)
> + ret = panel->funcs->prepare(panel);
> +
> + if (ret >= 0)
> + panel->prepared = true;
> +
> + return ret;
> }
> EXPORT_SYMBOL(drm_panel_prepare);
>
> @@ -85,10 +96,21 @@ EXPORT_SYMBOL(drm_panel_prepare);
> */
> int drm_panel_enable(struct drm_panel *panel)
> {
> - if (panel && panel->funcs && panel->funcs->enable)
> - return panel->funcs->enable(panel);
> + int ret = -ENOSYS;
>
> - return panel ? -ENOSYS : -EINVAL;
> + if (!panel)
> + return -EINVAL;
> +
> + if (panel->enabled)
> + return 0;
> +
> + if (panel->funcs && panel->funcs->enable)
> + ret = panel->funcs->enable(panel);
> +
> + if (ret >= 0)
> + panel->enabled = true;
> +
> + return ret;
> }
> EXPORT_SYMBOL(drm_panel_enable);
>
> @@ -104,10 +126,20 @@ EXPORT_SYMBOL(drm_panel_enable);
> */
> int drm_panel_disable(struct drm_panel *panel)
> {
> - if (panel && panel->funcs && panel->funcs->disable)
> - return panel->funcs->disable(panel);
> + int ret = -ENOSYS;
>
> - return panel ? -ENOSYS : -EINVAL;
> + if (!panel)
> + return -EINVAL;
> +
> + if (!panel->enabled)
> + return 0;
> +
> + if (panel->funcs && panel->funcs->disable)
> + ret = panel->funcs->disable(panel);
> +
> + panel->enabled = false;
> +
> + return ret;
> }
> EXPORT_SYMBOL(drm_panel_disable);
>
> @@ -124,10 +156,20 @@ EXPORT_SYMBOL(drm_panel_disable);
> */
> int drm_panel_unprepare(struct drm_panel *panel)
> {
> - if (panel && panel->funcs && panel->funcs->unprepare)
> - return panel->funcs->unprepare(panel);
> + int ret = -ENOSYS;
>
> - return panel ? -ENOSYS : -EINVAL;
> + if (!panel)
> + return -EINVAL;
> +
> + if (!panel->prepared)
> + return 0;
> +
> + if (panel->funcs && panel->funcs->unprepare)
> + ret = panel->funcs->unprepare(panel);
> +
> + panel->prepared = false;
> +
> + return ret;
> }
> EXPORT_SYMBOL(drm_panel_unprepare);
>
> diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h
> index 624bd15ecfab..7493500fc9bd 100644
> --- a/include/drm/drm_panel.h
> +++ b/include/drm/drm_panel.h
> @@ -65,6 +65,9 @@ struct drm_panel_funcs {
> * @prepare:
> *
> * Turn on panel and perform set up.
> + * When the panel is successfully prepared the prepare() function
> + * will not be called again until the panel has been unprepared.
> + *
> */
> int (*prepare)(struct drm_panel *panel);
>
> @@ -72,6 +75,8 @@ struct drm_panel_funcs {
> * @enable:
> *
> * Enable panel (turn on back light, etc.).
> + * When the panel is successfully enabled the enable() function
> + * will not be called again until the panel has been disabled.
> */
> int (*enable)(struct drm_panel *panel);
>
> @@ -79,6 +84,7 @@ struct drm_panel_funcs {
> * @disable:
> *
> * Disable panel (turn off back light, etc.).
> + * If the panel is already disabled the disable() function is not called.
> */
> int (*disable)(struct drm_panel *panel);
>
> @@ -86,6 +92,7 @@ struct drm_panel_funcs {
> * @unprepare:
> *
> * Turn off panel.
> + * If the panel is already unprepared the unprepare() function is not called.
> */
> int (*unprepare)(struct drm_panel *panel);
>
> @@ -145,6 +152,20 @@ struct drm_panel {
> * Panel entry in registry.
> */
> struct list_head list;
> +
> + /**
> + * @prepared:
> + *
> + * Set to true when the panel is successfully prepared.
> + */
> + bool prepared;
> +
> + /**
> + * @enabled:
> + *
> + * Set to true when the panel is successfully enabled.
> + */
> + bool enabled;
> };
>
> void drm_panel_init(struct drm_panel *panel);
--
Regards,
Laurent Pinchart
