drm/dsi: Implement dcs set/get display brightness

Add support for the JDI LT070ME05000 WUXGA DSI panel used in Nexus 7 2013 devices.

Programming sequence for the panel is was originally found in the android-msm-flo-3.4-lollipop-release branch from:
https://android.googlesource.com/kernel/msm.git

And video mode setting is from dsi-panel-jdi-dualmipi1-video.dtsi file in:

    git://codeaurora.org/kernel/msm-3.10.git  LNX.LA.3.6_rb1.27

Cc Archit Taneja <[email protected]>

Cc Rob Clark <[email protected]>

Cc Sumit Semwal <[email protected]>

Cc John Stultz <[email protected]>

Cc Emil Velikov <[email protected]>

Cc Thierry Reding <[email protected]>

Cc David Airlie <[email protected]>

Signed-off-by Sumit Semwal <[email protected]>

Signed-off-by John Stultz <[email protected]>

Signed-off-by Vinay Simha BN <[email protected]>

---
v1:
* sumit ported to drm/panel framework, john cherry-picked to mainline, folded down other fixes from Vinay and Archit, vinay removed interface setting cmd mode, video mode panel selected

v2:
* incorporated code reviews from theiry, archit
code style, alphabetical soring in Makefile, Kconfig, regulator_bulk, arrays of u8, generic helper function, documentation bindings,

v3:
* dcs backlight support added
* tested this panel driver in nexus7 2013 device

v4:
* backlight interface added in the panel driver
* incorporated width_mm and height_mm suggested by rob herring

v5:
* theirry review comments incorporated
panel model naming consistent, alphabetical soring in Kconfig Makefile, MAX_BRIGHTNESS dropped, regulator_names, parameterize panel width and height, descprition for control display, cabc and interface setting, temporary variable removed, consistent error reporting and commit message
* removed tear on/off, scanline, since these are required only for command mode panels

v6:
* emil review comments incorporated PANEL_NUM_REGULATORS dropped, return ret added at necessary places, if checks dropped for backlight and gpios

v7:
* emil review comments incorporated
added ARRAY_SIZE in struct, regulator_bulk_disable in poweroff, gpios checks dropped.
some returns cannot be dropped, since drm panel framework return type required.

---
 drivers/gpu/drm/panel/Kconfig                  |  11 +
 drivers/gpu/drm/panel/Makefile                 |   1 +
 drivers/gpu/drm/panel/panel-jdi-lt070me05000.c | 495 +++++++++++++++++++++++++
 3 files changed, 507 insertions(+)
 create mode 100644 drivers/gpu/drm/panel/panel-jdi-lt070me05000.c

drivers/gpu/drm/panel/Kconfig +11 -0

index 1500ab9..62aba97 100644
@@ -18,6 +18,17 @@ config DRM_PANEL_SIMPLE
          that it can be automatically turned off when the panel goes into a
          low power state.
 
+config DRM_PANEL_JDI_LT070ME05000
+       tristate "JDI LT070ME05000 WUXGA DSI panel"
+       depends on OF
+       depends on DRM_MIPI_DSI
+       depends on BACKLIGHT_CLASS_DEVICE
+       help
+         Say Y here if you want to enable support for JDI DSI video mode
+         panel as found in Google Nexus 7 (2013) devices.
+         The panel has a 1200(RGB)×1920 (WUXGA) resolution and uses
+         24 bit per pixel.
+
 config DRM_PANEL_SAMSUNG_LD9040
        tristate "Samsung LD9040 RGB/SPI panel"
        depends on OF && SPI

drivers/gpu/drm/panel/Makefile +1 -0

index f277eed..a5c7ec0 100644
@@ -1,4 +1,5 @@
 obj-$(CONFIG_DRM_PANEL_SIMPLE) += panel-simple.o
+obj-$(CONFIG_DRM_PANEL_JDI_LT070ME05000) += panel-jdi-lt070me05000.o
 obj-$(CONFIG_DRM_PANEL_LG_LG4573) += panel-lg-lg4573.o
 obj-$(CONFIG_DRM_PANEL_PANASONIC_VVX10F034N00) += panel-panasonic-vvx10f034n00.o
 obj-$(CONFIG_DRM_PANEL_SAMSUNG_LD9040) += panel-samsung-ld9040.o

drivers/gpu/drm/panel/panel-jdi-lt070me05000.c new file +495 -1

new file mode 100644
index 0000000..888fe2b
@@ -0,0 +1,495 @@
+/*
+ * Copyright (C) 2016 InforceComputing
+ * Author: Vinay Simha BN <[email protected]>
+ *
+ * Copyright (C) 2016 Linaro Ltd
+ * Author: Sumit Semwal <[email protected]>
+ *
+ * From internet archives, the panel for Nexus 7 2nd Gen, 2013 model is a
+ * JDI model LT070ME05000, and its data sheet is at:
+ * http://panelone.net/en/7-0-inch/JDI_LT070ME05000_7.0_inch-datasheet
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <linux/backlight.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regulator/consumer.h>
+
+#include <drm/drmP.h>
+#include <drm/drm_crtc.h>
+#include <drm/drm_mipi_dsi.h>
+#include <drm/drm_panel.h>
+
+#include <video/mipi_display.h>
+
+static const char * const regulator_names[] = {
+       "vddp",
+       "dcdc_en",
+       "vcc"
+};
+
+struct jdi_panel {
+       struct drm_panel base;
+       struct mipi_dsi_device *dsi;
+
+       struct regulator_bulk_data supplies[ARRAY_SIZE(regulator_names)];
+
+       struct gpio_desc *reset_gpio;
+       struct gpio_desc *enable_gpio;
+       struct backlight_device *backlight;
+
+       bool prepared;
+       bool enabled;
+
+       const struct drm_display_mode *mode;
+};
+
+static inline struct jdi_panel *to_jdi_panel(struct drm_panel *panel)
+{
+       return container_of(panel, struct jdi_panel, base);
+}
+
+static int jdi_panel_init(struct jdi_panel *jdi)
+{
+       struct mipi_dsi_device *dsi = jdi->dsi;
+       int ret;
+
+       dsi->mode_flags |= MIPI_DSI_MODE_LPM;
+
+       ret = mipi_dsi_dcs_soft_reset(dsi);
+       if (ret < 0)
+               return ret;
+
+       usleep_range(10000, 20000);
+
+       ret = mipi_dsi_dcs_set_pixel_format(dsi, MIPI_DCS_PIXEL_FMT_24BIT << 4);
+       if (ret < 0)
+               return ret;
+
+       ret = mipi_dsi_dcs_set_column_address(dsi, 0, jdi->mode->hdisplay - 1);
+       if (ret < 0)
+               return ret;
+
+       ret = mipi_dsi_dcs_set_page_address(dsi, 0, jdi->mode->vdisplay - 1);
+       if (ret < 0)
+               return ret;
+
+       /*
+        * BIT(5) BCTRL = 1 Backlight Control Block On, Brightness registers
+        *                  are active
+        * BIT(3) BL = 1    Backlight Control On
+        * BIT(2) DD = 0    Display Dimming is Off
+        */
+       ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_WRITE_CONTROL_DISPLAY,
+                                (u8[]){ 0x24 }, 1);
+       if (ret < 0)
+               return ret;
+
+       /* CABC off */
+       ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_WRITE_POWER_SAVE,
+                                (u8[]){ 0x00 }, 1);
+       if (ret < 0)
+               return ret;
+
+       ret = mipi_dsi_dcs_exit_sleep_mode(dsi);
+       if (ret < 0)
+               return ret;
+
+       msleep(120);
+
+       ret = mipi_dsi_generic_write(dsi, (u8[]){0xB0, 0x00}, 2);
+       if (ret < 0)
+               return ret;
+
+       mdelay(10);
+
+       /* Interface setting, video mode */
+       ret = mipi_dsi_generic_write(dsi, (u8[])
+                                    {0xB3, 0x26, 0x08, 0x00, 0x20, 0x00}, 6);
+       if (ret < 0)
+               return ret;
+
+       mdelay(20);
+
+       ret = mipi_dsi_generic_write(dsi, (u8[]){0xB0, 0x03}, 2);
+
+       return ret;
+}
+
+static int jdi_panel_on(struct jdi_panel *jdi)
+{
+       struct mipi_dsi_device *dsi = jdi->dsi;
+       int ret;
+
+       dsi->mode_flags |= MIPI_DSI_MODE_LPM;
+
+       ret = mipi_dsi_dcs_set_display_on(dsi);
+
+       return ret;
+}
+
+static int jdi_panel_off(struct jdi_panel *jdi)
+{
+       struct mipi_dsi_device *dsi = jdi->dsi;
+       int ret;
+
+       dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
+
+       ret = mipi_dsi_dcs_set_display_off(dsi);
+       if (ret < 0)
+               return ret;
+
+       ret = mipi_dsi_dcs_enter_sleep_mode(dsi);
+
+       msleep(100);
+
+       return ret;
+}
+
+static int jdi_panel_disable(struct drm_panel *panel)
+{
+       struct jdi_panel *jdi = to_jdi_panel(panel);
+
+       if (!jdi->enabled)
+               return 0;
+
+       jdi->backlight->props.power = FB_BLANK_POWERDOWN;
+       backlight_update_status(jdi->backlight);
+
+       jdi->enabled = false;
+
+       return 0;
+}
+
+static int jdi_panel_unprepare(struct drm_panel *panel)
+{
+       struct jdi_panel *jdi = to_jdi_panel(panel);
+       struct device *dev = &jdi->dsi->dev;
+       int ret;
+
+       if (!jdi->prepared)
+               return 0;
+
+       ret = jdi_panel_off(jdi);
+       if (ret) {
+               dev_err(panel->dev, "failed to set panel off: %d\n", ret);
+               return ret;
+       }
+
+       ret = regulator_bulk_disable(ARRAY_SIZE(jdi->supplies), jdi->supplies);
+       if (ret < 0)
+               dev_err(dev, "regulator disable failed, %d\n", ret);
+
+       gpiod_set_value(jdi->enable_gpio, 0);
+
+       gpiod_set_value(jdi->reset_gpio, 0);
+
+       jdi->prepared = false;
+
+       return ret;
+}
+
+static int jdi_panel_prepare(struct drm_panel *panel)
+{
+       struct jdi_panel *jdi = to_jdi_panel(panel);
+       struct device *dev = &jdi->dsi->dev;
+       int ret;
+
+       if (jdi->prepared)
+               return 0;
+
+       ret = regulator_bulk_enable(ARRAY_SIZE(jdi->supplies), jdi->supplies);
+       if (ret < 0) {
+               dev_err(dev, "regulator enable failed, %d\n", ret);
+               return ret;
+       }
+
+       msleep(20);
+
+       gpiod_set_value(jdi->reset_gpio, 1);
+       usleep_range(10, 20);
+
+       gpiod_set_value(jdi->enable_gpio, 1);
+       usleep_range(10, 20);
+
+       ret = jdi_panel_init(jdi);
+       if (ret < 0) {
+               dev_err(panel->dev, "failed to init panel: %d\n", ret);
+               goto poweroff;
+       }
+
+       ret = jdi_panel_on(jdi);
+       if (ret < 0) {
+               dev_err(panel->dev, "failed to set panel on: %d\n", ret);
+               goto poweroff;
+       }
+
+       jdi->prepared = true;
+
+       return 0;
+
+poweroff:
+       ret = regulator_bulk_disable(ARRAY_SIZE(jdi->supplies), jdi->supplies);
+       if (ret < 0)
+               dev_err(dev, "regulator disable failed, %d\n", ret);
+
+       gpiod_set_value(jdi->enable_gpio, 0);
+
+       gpiod_set_value(jdi->reset_gpio, 0);
+
+       return ret;
+}
+
+static int jdi_panel_enable(struct drm_panel *panel)
+{
+       struct jdi_panel *jdi = to_jdi_panel(panel);
+
+       if (jdi->enabled)
+               return 0;
+
+       jdi->backlight->props.power = FB_BLANK_UNBLANK;
+       backlight_update_status(jdi->backlight);
+
+       jdi->enabled = true;
+
+       return 0;
+}
+
+static const struct drm_display_mode default_mode = {
+               .clock = 155493,
+               .hdisplay = 1200,
+               .hsync_start = 1200 + 48,
+               .hsync_end = 1200 + 48 + 32,
+               .htotal = 1200 + 48 + 32 + 60,
+               .vdisplay = 1920,
+               .vsync_start = 1920 + 3,
+               .vsync_end = 1920 + 3 + 5,
+               .vtotal = 1920 + 3 + 5 + 6,
+               .vrefresh = 60,
+               .flags = 0,
+};
+
+static int jdi_panel_get_modes(struct drm_panel *panel)
+{
+       struct drm_display_mode *mode;
+       struct jdi_panel *jdi = to_jdi_panel(panel);
+       struct device *dev = &jdi->dsi->dev;
+
+       mode = drm_mode_duplicate(panel->drm, &default_mode);
+       if (!mode) {
+               dev_err(dev, "failed to add mode %ux%ux@%u\n",
+                       default_mode.hdisplay, default_mode.vdisplay,
+                       default_mode.vrefresh);
+               return -ENOMEM;
+       }
+
+       drm_mode_set_name(mode);
+
+       drm_mode_probed_add(panel->connector, mode);
+
+       panel->connector->display_info.width_mm = 95;
+       panel->connector->display_info.height_mm = 151;
+
+       return 1;
+}
+
+static int dsi_dcs_bl_get_brightness(struct backlight_device *bl)
+{
+       struct mipi_dsi_device *dsi = bl_get_data(bl);
+       int ret;
+       u16 brightness = bl->props.brightness;
+
+       dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
+
+       ret = mipi_dsi_dcs_get_display_brightness(dsi, &brightness);
+       if (ret < 0)
+               return ret;
+
+       dsi->mode_flags |= MIPI_DSI_MODE_LPM;
+
+       return brightness & 0xff;
+}
+
+static int dsi_dcs_bl_update_status(struct backlight_device *bl)
+{
+       struct mipi_dsi_device *dsi = bl_get_data(bl);
+       int ret;
+
+       dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
+
+       ret = mipi_dsi_dcs_set_display_brightness(dsi, bl->props.brightness);
+       if (ret < 0)
+               return ret;
+
+       dsi->mode_flags |= MIPI_DSI_MODE_LPM;
+
+       return 0;
+}
+
+static const struct backlight_ops dsi_bl_ops = {
+       .update_status = dsi_dcs_bl_update_status,
+       .get_brightness = dsi_dcs_bl_get_brightness,
+};
+
+struct backlight_device *
+drm_panel_create_dsi_backlight(struct mipi_dsi_device *dsi)
+{
+       struct device *dev = &dsi->dev;
+       struct backlight_properties props;
+
+       memset(&props, 0, sizeof(props));
+       props.type = BACKLIGHT_RAW;
+       props.brightness = 255;
+       props.max_brightness = 255;
+
+       return devm_backlight_device_register(dev, dev_name(dev), dev, dsi,
+                                             &dsi_bl_ops, &props);
+}
+
+static const struct drm_panel_funcs jdi_panel_funcs = {
+       .disable = jdi_panel_disable,
+       .unprepare = jdi_panel_unprepare,
+       .prepare = jdi_panel_prepare,
+       .enable = jdi_panel_enable,
+       .get_modes = jdi_panel_get_modes,
+};
+
+static const struct of_device_id jdi_of_match[] = {
+       { .compatible = "jdi,lt070me05000", },
+       { }
+};
+MODULE_DEVICE_TABLE(of, jdi_of_match);
+
+static int jdi_panel_add(struct jdi_panel *jdi)
+{
+       struct device *dev = &jdi->dsi->dev;
+       int ret;
+       unsigned int i;
+
+       jdi->mode = &default_mode;
+
+       for (i = 0; i < ARRAY_SIZE(jdi->supplies); i++)
+               jdi->supplies[i].supply = regulator_names[i];
+
+       ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(jdi->supplies),
+                                     jdi->supplies);
+       if (ret < 0) {
+               dev_err(dev, "failed to init regulator, ret=%d\n", ret);
+               return ret;
+       }
+
+       jdi->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
+       if (IS_ERR(jdi->reset_gpio)) {
+               ret = PTR_ERR(jdi->reset_gpio);
+               dev_err(dev, "cannot get reset-gpios %d\n", ret);
+               return ret;
+       }
+
+       jdi->enable_gpio = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
+       if (IS_ERR(jdi->enable_gpio)) {
+               ret = PTR_ERR(jdi->enable_gpio);
+               dev_err(dev, "cannot get enable-gpio %d\n", ret);
+               return ret;
+       }
+
+       jdi->backlight = drm_panel_create_dsi_backlight(jdi->dsi);
+       if (IS_ERR(jdi->backlight)) {
+               ret = PTR_ERR(jdi->backlight);
+               dev_err(dev, "failed to register backlight %d\n", ret);
+               return ret;
+       }
+
+       drm_panel_init(&jdi->base);
+       jdi->base.funcs = &jdi_panel_funcs;
+       jdi->base.dev = &jdi->dsi->dev;
+
+       ret = drm_panel_add(&jdi->base);
+
+       return ret;
+}
+
+static void jdi_panel_del(struct jdi_panel *jdi)
+{
+       if (jdi->base.dev)
+               drm_panel_remove(&jdi->base);
+}
+
+static int jdi_panel_probe(struct mipi_dsi_device *dsi)
+{
+       struct jdi_panel *jdi;
+       int ret;
+
+       dsi->lanes = 4;
+       dsi->format = MIPI_DSI_FMT_RGB888;
+       dsi->mode_flags =  MIPI_DSI_MODE_VIDEO_HSE | MIPI_DSI_MODE_VIDEO |
+                          MIPI_DSI_CLOCK_NON_CONTINUOUS;
+
+       jdi = devm_kzalloc(&dsi->dev, sizeof(*jdi), GFP_KERNEL);
+       if (!jdi)
+               return -ENOMEM;
+
+       mipi_dsi_set_drvdata(dsi, jdi);
+
+       jdi->dsi = dsi;
+
+       ret = jdi_panel_add(jdi);
+       if (ret < 0)
+               return ret;
+
+       return mipi_dsi_attach(dsi);
+}
+
+static int jdi_panel_remove(struct mipi_dsi_device *dsi)
+{
+       struct jdi_panel *jdi = mipi_dsi_get_drvdata(dsi);
+       int ret;
+
+       ret = jdi_panel_disable(&jdi->base);
+       if (ret < 0)
+               dev_err(&dsi->dev, "failed to disable panel: %d\n", ret);
+
+       ret = mipi_dsi_detach(dsi);
+       if (ret < 0)
+               dev_err(&dsi->dev, "failed to detach from DSI host: %d\n",
+                       ret);
+
+       drm_panel_detach(&jdi->base);
+       jdi_panel_del(jdi);
+
+       return 0;
+}
+
+static void jdi_panel_shutdown(struct mipi_dsi_device *dsi)
+{
+       struct jdi_panel *jdi = mipi_dsi_get_drvdata(dsi);
+
+       jdi_panel_disable(&jdi->base);
+}
+
+static struct mipi_dsi_driver jdi_panel_driver = {
+       .driver = {
+               .name = "panel-jdi-lt070me05000",
+               .of_match_table = jdi_of_match,
+       },
+       .probe = jdi_panel_probe,
+       .remove = jdi_panel_remove,
+       .shutdown = jdi_panel_shutdown,
+};
+module_mipi_dsi_driver(jdi_panel_driver);
+
+MODULE_AUTHOR("Sumit Semwal <[email protected]>");
+MODULE_AUTHOR("Vinay Simha BN <[email protected]>");
+MODULE_DESCRIPTION("JDI LT070ME05000 WUXGA");
+MODULE_LICENSE("GPL v2");
--

2.1.2

hi,

Any further comments or reviews?

Quoted 4 lines · Vinay Simha

hi,

Any further comments or reviews?

You still haven't covered my earlier suggestions, as such I cannot give you a r-b :-( They are not blockers by any means, but it'll be up-to the maintainer to ack/pick this up.

Thierry ?

Regards,
Emil

Quoted 5 lines · Emil Velikov

Quoted 4 lines · Vinay Simha

hi,

Any further comments or reviews?

Quoted 3 lines

You still haven't covered my earlier suggestions, as such I cannot give you a r-b :-( They are not blockers by any means, but it'll be up-to the maintainer to ack/pick this up.

i do have covered the suggestions from you.
As i had mentioned earlier we cannot drop few returns and keep it void(drm_panel_funcs - unprepare), since drm framework requires return. if do you have any alternate solution please suggest, will incorporate.

Quoted 4 lines · Vinay Simha

hi,

Any further comments or reviews?

You still haven't covered my earlier suggestions, as such I cannot give you a r-b :-( They are not blockers by any means, but it'll be up-to the maintainer to ack/pick this up.

Thierry ?

Quoted 10 lines · Emil Velikov

Quoted 4 lines · Vinay Simha

hi,

Any further comments or reviews?

You still haven't covered my earlier suggestions, as such I cannot give you a r-b :-( They are not blockers by any means, but it'll be up-to the maintainer to ack/pick this up.

Thierry ?

Vinay, please address Emil's comments and resend. I also see that you stopped sending the device tree bindings patch at some point. Please do include that when you repost as I don't seem to be able to find a recent version anywhere.

Thierry

emil,

As you had suggested to drop the spurious returns in jdi_panel_unprepare and drop the return itself.
But as i had mentioned earlier , we cannot drop the return function and void for jdi_panel_unprepare , since the drm fun* requires int as return type (drm_panel_funcs .unprepare).

please do re-point out if i had still missed anything.

Provide a small convenience wrapper that set/get the display brightness value

Cc John Stultz <[email protected]>

Cc Sumit Semwal <[email protected]>

Cc Archit Taneja <[email protected]>

Cc Rob Clark <[email protected]>

Cc Jani Nikula <[email protected]>

Cc Thierry Reding <[email protected]>

Signed-off-by Vinay Simha BN <[email protected]>

---
v1:
*tested in nexus7 2nd gen.

v2:
* implemented jani review comments
-functions name mapped accordingly
-bl value increased from 0xff to 0xffff -backlight interface will be handled in panel driver,
so it is moved from the mipi_dsi helper function

---
 drivers/gpu/drm/drm_mipi_dsi.c | 49 ++++++++++++++++++++++++++++++++++++++++++
 include/drm/drm_mipi_dsi.h     |  4 ++++
 2 files changed, 53 insertions(+)

drivers/gpu/drm/drm_mipi_dsi.c +49 -0

index 49311fc..2c03784 100644
@@ -1041,6 +1041,55 @@ int mipi_dsi_dcs_set_pixel_format(struct mipi_dsi_device *dsi, u8 format)
 }
 EXPORT_SYMBOL(mipi_dsi_dcs_set_pixel_format);
 
+/**
+ * mipi_dsi_dcs_get_display_brightness() - gets the current brightness value
+ * of the display
+ * @dsi: DSI peripheral device
+ * @brightness: brightness value
+ *
+ * Return: 0 on success or a negative error code on failure.
+ */
+int mipi_dsi_dcs_get_display_brightness(struct mipi_dsi_device *dsi,
+                                       u16 *brightness)
+{
+       ssize_t err;
+
+       err = mipi_dsi_dcs_read(dsi, MIPI_DCS_GET_DISPLAY_BRIGHTNESS,
+                               brightness, sizeof(*brightness));
+       if (err < 0) {
+               if (err == 0)
+                       err = -ENODATA;
+
+               return err;
+       }
+
+       return 0;
+}
+EXPORT_SYMBOL(mipi_dsi_dcs_get_display_brightness);
+
+/**
+ * mipi_dsi_dcs_set_display_brightness() - sets the brightness value of
+ * the display
+ * @dsi: DSI peripheral device
+ * @brightness: brightness value
+ *
+ * Return: 0 on success or a negative error code on failure.
+ */
+int mipi_dsi_dcs_set_display_brightness(struct mipi_dsi_device *dsi,
+                                       u16 brightness)
+{
+       ssize_t err;
+       u8 bl_value[2] = { brightness & 0xff, brightness >> 8 };
+
+       err = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
+                                bl_value, sizeof(bl_value));
+       if (err < 0)
+               return err;
+
+       return 0;
+}
+EXPORT_SYMBOL(mipi_dsi_dcs_set_display_brightness);
+
 static int mipi_dsi_drv_probe(struct device *dev)
 {
        struct mipi_dsi_driver *drv = to_mipi_dsi_driver(dev->driver);

include/drm/drm_mipi_dsi.h +4 -1

index 72f5b15..4d77bb0 100644
@@ -270,6 +270,10 @@ int mipi_dsi_dcs_set_tear_off(struct mipi_dsi_device *dsi);
 int mipi_dsi_dcs_set_tear_on(struct mipi_dsi_device *dsi,
                             enum mipi_dsi_dcs_tear_mode mode);
 int mipi_dsi_dcs_set_pixel_format(struct mipi_dsi_device *dsi, u8 format);
+int mipi_dsi_dcs_get_display_brightness(struct mipi_dsi_device *dsi,
+                                       u16 *brightness);
+int mipi_dsi_dcs_set_display_brightness(struct mipi_dsi_device *dsi,
+                                       u16 brightness);
 
 /**
  * struct mipi_dsi_driver - DSI driver
--

2.1.2