From 45527d435c5e39b6eec4aa0065a562e7cf05d503 Mon Sep 17 00:00:00 2001 From: Ajay Kumar Date: Fri, 18 Jul 2014 02:13:48 +0530 Subject: drm/panel: add .prepare() and .unprepare() functions Panels often require an initialization sequence that consists of three steps: a) powering up the panel, b) starting transmission of video data and c) enabling the panel (e.g. turn on backlight). This is usually necessary to avoid visual glitches at the beginning of video data transmission. Similarly, the shutdown sequence is typically done in three steps as well: a) disable the panel (e.g. turn off backlight), b) cease video data transmission and c) power down the panel. Currently drivers can only implement .enable() and .disable() functions, which is not enough to implement the above sequences. This commit adds a second pair of functions, .prepare() and .unprepare() to allow more fine-grained control over when the above steps are performed. Signed-off-by: Ajay Kumar [treding: rewrite changelog, add kerneldoc] Signed-off-by: Thierry Reding --- include/drm/drm_panel.h | 50 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) (limited to 'include/drm/drm_panel.h') diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h index c2ab77add67c..29e3daf1b25d 100644 --- a/include/drm/drm_panel.h +++ b/include/drm/drm_panel.h @@ -30,8 +30,42 @@ struct drm_connector; struct drm_device; struct drm_panel; +/** + * struct drm_panel_funcs - perform operations on a given panel + * @disable: disable panel (turn off back light, etc.) + * @unprepare: turn off panel + * @prepare: turn on panel and perform set up + * @enable: enable panel (turn on back light, etc.) + * @get_modes: add modes to the connector that the panel is attached to and + * return the number of modes added + * + * The .prepare() function is typically called before the display controller + * starts to transmit video data. Panel drivers can use this to turn the panel + * on and wait for it to become ready. If additional configuration is required + * (via a control bus such as I2C, SPI or DSI for example) this is a good time + * to do that. + * + * After the display controller has started transmitting video data, it's safe + * to call the .enable() function. This will typically enable the backlight to + * make the image on screen visible. Some panels require a certain amount of + * time or frames before the image is displayed. This function is responsible + * for taking this into account before enabling the backlight to avoid visual + * glitches. + * + * Before stopping video transmission from the display controller it can be + * necessary to turn off the panel to avoid visual glitches. This is done in + * the .disable() function. Analogously to .enable() this typically involves + * turning off the backlight and waiting for some time to make sure no image + * is visible on the panel. It is then safe for the display controller to + * cease transmission of video data. + * + * To save power when no video data is transmitted, a driver can power down + * the panel. This is the job of the .unprepare() function. + */ struct drm_panel_funcs { int (*disable)(struct drm_panel *panel); + int (*unprepare)(struct drm_panel *panel); + int (*prepare)(struct drm_panel *panel); int (*enable)(struct drm_panel *panel); int (*get_modes)(struct drm_panel *panel); }; @@ -46,6 +80,14 @@ struct drm_panel { struct list_head list; }; +static inline int drm_panel_unprepare(struct drm_panel *panel) +{ + if (panel && panel->funcs && panel->funcs->unprepare) + return panel->funcs->unprepare(panel); + + return panel ? -ENOSYS : -EINVAL; +} + static inline int drm_panel_disable(struct drm_panel *panel) { if (panel && panel->funcs && panel->funcs->disable) @@ -54,6 +96,14 @@ static inline int drm_panel_disable(struct drm_panel *panel) return panel ? -ENOSYS : -EINVAL; } +static inline int drm_panel_prepare(struct drm_panel *panel) +{ + if (panel && panel->funcs && panel->funcs->prepare) + return panel->funcs->prepare(panel); + + return panel ? -ENOSYS : -EINVAL; +} + static inline int drm_panel_enable(struct drm_panel *panel) { if (panel && panel->funcs && panel->funcs->enable) -- cgit v1.2.3 From 7bf93c73adb28d8db6b34c27d3edd96337a2d366 Mon Sep 17 00:00:00 2001 From: Ajay Kumar Date: Wed, 30 Jul 2014 12:02:15 +0200 Subject: drm/panel: Provide convenience wrapper for .get_modes() Add a convenience wrapper for the struct drm_panel_funcs' .get_modes() function so that not every driver needs to check that the panel driver implements the function before calling it. Signed-off-by: Ajay Kumar [treding: extract from larger patch, commit message] Signed-off-by: Thierry Reding --- include/drm/drm_panel.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'include/drm/drm_panel.h') diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h index 29e3daf1b25d..1fbcc96063a7 100644 --- a/include/drm/drm_panel.h +++ b/include/drm/drm_panel.h @@ -112,6 +112,14 @@ static inline int drm_panel_enable(struct drm_panel *panel) return panel ? -ENOSYS : -EINVAL; } +static inline int drm_panel_get_modes(struct drm_panel *panel) +{ + if (panel && panel->funcs && panel->funcs->get_modes) + return panel->funcs->get_modes(panel); + + return panel ? -ENOSYS : -EINVAL; +} + void drm_panel_init(struct drm_panel *panel); int drm_panel_add(struct drm_panel *panel); -- cgit v1.2.3