[v2,01/25] drm/drm_panel: no error when no callback
diff mbox series

Message ID 20191207140353.23967-2-sam@ravnborg.org
State Not Applicable
Headers show
Series
  • drm/panel infrastructure + backlight update
Related show

Commit Message

Sam Ravnborg Dec. 7, 2019, 2:03 p.m. UTC
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@ravnborg.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
---
 drivers/gpu/drm/drm_panel.c | 35 +++++++++++++++++++++++++----------
 include/drm/drm_panel.h     | 18 ++++++++++++++++--
 2 files changed, 41 insertions(+), 12 deletions(-)

Comments

Laurent Pinchart Dec. 9, 2019, 12:50 a.m. UTC | #1
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@ravnborg.org>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Maxime Ripard <mripard@kernel.org>
> Cc: Thierry Reding <thierry.reding@gmail.com>
> Cc: Sam Ravnborg <sam@ravnborg.org>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> ---
>  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);

Patch
diff mbox series

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.
 	 */
 	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);