[PATCH v1 15/16] drm/panel: add backlight support

From: Sam Ravnborg <sam@ravnborg•org>
To: dri-devel@lists•freedesktop.org,
	Thierry Reding <thierry.reding@gmail•com>
Cc: Neil Armstrong <narmstrong@baylibre•com>,
	David Airlie <airlied@linux•ie>,
	Linus Walleij <linus.walleij@linaro•org>,
	Stefan Agner <stefan@agner•ch>,
	Andrzej Hajda <a.hajda@samsung•com>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard•com>,
	Benjamin Gaignard <benjamin.gaignard@linaro•org>,
	Fabio Estevam <festevam@gmail•com>, Marek Vasut <marex@denx•de>,
	Laurent Pinchart <laurent.pinchart+renesas@ideasonboard•com>,
	Joonyoung Shim <jy0922.shim@samsung•com>,
	Sam Ravnborg <sam@ravnborg•org>,
	Krzysztof Kozlowski <krzk@kernel•org>,
	Jonathan Hunter <jonathanh@nvidia•com>,
	Maxime Ripard <maxime.ripard@bootlin•com>,
	Kukjin Kim <kgene@kernel•org>,
	Allison Randal <allison@lohutok•net>,
	Philipp Zabel <p.zabel@pengutronix•de>,
	NXP Linux Team <linux-imx@nxp•com>,
	Pengutronix Kernel Team <kernel@pengutronix•de>,
	Jonas Karlman <jonas@kwiboo•se>,
	Sascha Hauer <s.hauer@pengutronix•de>,
	Alison Wang <alison.wang@nxp•com>,
	Maarten Lankhorst <maarten.lankhorst@linux•intel.com>,
	Gwan-gyeong Mun <gwan-gyeong.mun@intel•com>,
	Inki Dae <inki.dae@samsung•com>,
	Alexios Zavras <alexios.zavras@intel•com>,
	linux-samsung-soc@vger•kernel.org, linux-tegra@vger•kernel.org,
	Thomas Gleixner <tglx@linutronix•de>, Sean Paul <sean@poorly•run>,
	linux-arm-kernel@lists•infradead.org,
	Jernej Skrabec <jernej.skrabec@siol•net>,
	Shawn Guo <shawnguo@kernel•org>,
	Seung-Woo Kim <sw0312.kim@samsung•com>,
	Vincent Abriou <vincent.abriou@st•com>,
	Kyungmin Park <kyungmin.park@samsung•com>,
	Daniel Vetter <daniel@ffwll•ch>, Enrico Weigelt <info@metux•net>
Subject: [PATCH v1 15/16] drm/panel: add backlight support
Date: Sun,  4 Aug 2019 22:16:36 +0200	[thread overview]
Message-ID: <20190804201637.1240-16-sam@ravnborg.org> (raw)
In-Reply-To: <20190804201637.1240-1-sam@ravnborg.org>

Panels often supports backlight as specified in a device tree.
Update the drm_panel infrastructure to support this to
simplify the drivers.

With this the panel driver just needs to add the following to the
probe() function:

    err = drm_panel_of_backlight(panel);
    if (err)
            return err;

Then drm_panel will handle all the rest.

Signed-off-by: Sam Ravnborg <sam@ravnborg•org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux•intel.com>
Cc: Maxime Ripard <maxime.ripard@bootlin•com>
Cc: Sean Paul <sean@poorly•run>
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 | 41 +++++++++++++++++++++++++++++++++++++
 include/drm/drm_panel.h     | 23 +++++++++++++++++++++
 2 files changed, 64 insertions(+)

diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
index 0853764040de..d8139674b883 100644
--- a/drivers/gpu/drm/drm_panel.c
+++ b/drivers/gpu/drm/drm_panel.c
@@ -21,6 +21,7 @@
  * DEALINGS IN THE SOFTWARE.
  */
 
+#include <linux/backlight.h>
 #include <linux/err.h>
 #include <linux/module.h>
 
@@ -110,6 +111,7 @@ int drm_panel_enable(struct drm_panel *panel)
 	if (ret >= 0)
 		panel->enabled = true;
 
+	backlight_enable(panel->backlight);
 	return ret;
 }
 EXPORT_SYMBOL(drm_panel_enable);
@@ -134,6 +136,8 @@ int drm_panel_disable(struct drm_panel *panel)
 	if (!panel->enabled)
 		return 0;
 
+	backlight_disable(panel->backlight);
+
 	if (panel->funcs && panel->funcs->disable)
 		ret = panel->funcs->disable(panel);
 
@@ -308,6 +312,43 @@ struct drm_panel *of_drm_find_panel(const struct device_node *np)
 EXPORT_SYMBOL(of_drm_find_panel);
 #endif
 
+#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
+/**
+ * drm_panel_of_backlight - use backlight device node for backlight
+ * @panel: DRM panel
+ *
+ * Use this function to enable backlight handling if your panel
+ * uses device tree and has a backlight handle.
+ *
+ * When panel is enabled backlight will be enabled after a
+ * successfull call to &drm_panel_funcs.enable()
+ *
+ * When panel is disabled backlight will be disabled before the
+ * call to &drm_panel_funcs.disable().
+ *
+ * A typical implementation for a panel driver supporting device tree
+ * will call this function and then backlight just works.
+ *
+ * Return: 0 on success or a negative error code on failure.
+ */
+int drm_panel_of_backlight(struct drm_panel *panel)
+{
+	struct backlight_device *backlight;
+
+	if (!panel || !panel->dev)
+		return -EINVAL;
+
+	backlight = devm_of_find_backlight(panel->dev);
+
+	if (IS_ERR(backlight))
+                return PTR_ERR(backlight);
+
+	panel->backlight = backlight;
+	return 0;
+}
+EXPORT_SYMBOL(drm_panel_of_backlight);
+#endif
+
 MODULE_AUTHOR("Thierry Reding <treding@nvidia•com>");
 MODULE_DESCRIPTION("DRM panel infrastructure");
 MODULE_LICENSE("GPL and additional rights");
diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h
index 7493500fc9bd..31349c2393b7 100644
--- a/include/drm/drm_panel.h
+++ b/include/drm/drm_panel.h
@@ -28,6 +28,7 @@
 #include <linux/errno.h>
 #include <linux/list.h>
 
+struct backlight_device;
 struct device_node;
 struct drm_connector;
 struct drm_device;
@@ -59,6 +60,10 @@ struct display_timing;
  *
  * To save power when no video data is transmitted, a driver can power down
  * the panel. This is the job of the .unprepare() function.
+ *
+ * Backlight can be handled automatically if configured using
+ * drm_panel_of_backlight(). Then the driver do not need to implement the
+ * functionality to enable/disable backlight.
  */
 struct drm_panel_funcs {
 	/**
@@ -139,6 +144,15 @@ struct drm_panel {
 	 */
 	struct device *dev;
 
+	/**
+	 * @backlight:
+	 *
+	 * Backlight device, used to turn on backlight after
+	 * the call to enable(), and to turn off
+	 * backlight before call to disable().
+	 */
+	struct backlight_device *backlight;
+
 	/**
 	 * @funcs:
 	 *
@@ -193,4 +207,13 @@ static inline struct drm_panel *of_drm_find_panel(const struct device_node *np)
 }
 #endif
 
+#if defined(CONFIG_BACKLIGHT_CLASS_DEVICE) && defined(CONFIG_DRM_PANEL)
+int drm_panel_of_backlight(struct drm_panel *panel);
+#else
+static inline int drm_panel_of_backlight(struct drm_panel *panel)
+{
+	return -EINVAL;
+}
+#endif
+
 #endif
-- 
2.20.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists•infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
