Re: [PATCH 2/2] drm/panel: Add Truly NT35521 panel driver

Hi Shawn,

Thanks for the patch!

On Wed, Aug 04, 2021 at 04:13:52PM +0800, Shawn Guo wrote:

It adds a drm driver for Truly NT35521 5.24" 1280x720 DSI panel, which can be found on Sony Xperia M4 Aqua phone. The panel backlight is managed through DSI link.

Signed-off-by: Shawn Guo shawn.guo@linaro.org

drivers/gpu/drm/panel/Kconfig | 9 + drivers/gpu/drm/panel/Makefile | 1 + drivers/gpu/drm/panel/panel-truly-nt35521.c | 491 ++++++++++++++++++++ 3 files changed, 501 insertions(+) create mode 100644 drivers/gpu/drm/panel/panel-truly-nt35521.c

diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig index ef87d92cdf49..cdc4abd5c40c 100644 --- a/drivers/gpu/drm/panel/Kconfig +++ b/drivers/gpu/drm/panel/Kconfig @@ -537,6 +537,15 @@ config DRM_PANEL_TPO_TPG110 400CH LTPS TFT LCD Single Chip Digital Driver for up to 800x400 LCD panels.

+config DRM_PANEL_TRULY_NT35521

• tristate "Truly NT35521 panel"

I think the name "Truly NT35521" is a bit too generic. AFAIK "Truly" is a panel vendor and the NovaTek NT35521 is the panel controller. But there are almost certainly other Truly panels that were also combined with a NT35521 but need a slightly different configuration.

If you don't know more than "Truly NT35521" based on the Sony sources, maybe do it similar to "asus,z00t-tm5p5-n35596" and use a compatible like "sony,<device>-truly-nt35521". Would be good to clarify the Kconfig option here too.

• depends on OF
• depends on DRM_MIPI_DSI
• depends on BACKLIGHT_CLASS_DEVICE
• help

•  Say Y here if you want to enable support for Truly NT35521
  

•  1280x720 DSI panel.
  

config DRM_PANEL_TRULY_NT35597_WQXGA tristate "Truly WQXGA" depends on OF diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile index cae4d976c069..3d3c98cb7a7b 100644 --- a/drivers/gpu/drm/panel/Makefile +++ b/drivers/gpu/drm/panel/Makefile @@ -56,6 +56,7 @@ obj-$(CONFIG_DRM_PANEL_TDO_TL070WSH30) += panel-tdo-tl070wsh30.o obj-$(CONFIG_DRM_PANEL_TPO_TD028TTEC1) += panel-tpo-td028ttec1.o obj-$(CONFIG_DRM_PANEL_TPO_TD043MTEA1) += panel-tpo-td043mtea1.o obj-$(CONFIG_DRM_PANEL_TPO_TPG110) += panel-tpo-tpg110.o +obj-$(CONFIG_DRM_PANEL_TRULY_NT35521) += panel-truly-nt35521.o obj-$(CONFIG_DRM_PANEL_TRULY_NT35597_WQXGA) += panel-truly-nt35597.o obj-$(CONFIG_DRM_PANEL_VISIONOX_RM69299) += panel-visionox-rm69299.o obj-$(CONFIG_DRM_PANEL_XINPENG_XPP055C272) += panel-xinpeng-xpp055c272.o diff --git a/drivers/gpu/drm/panel/panel-truly-nt35521.c b/drivers/gpu/drm/panel/panel-truly-nt35521.c new file mode 100644 index 000000000000..ea3cfb46be7e --- /dev/null +++ b/drivers/gpu/drm/panel/panel-truly-nt35521.c @@ -0,0 +1,491 @@ +// SPDX-License-Identifier: GPL-2.0 +/*

• • Copyright (c) 2021, Linaro Limited
• */

+#include <linux/backlight.h> +#include <linux/delay.h> +#include <linux/gpio/consumer.h> +#include <linux/module.h>

+#include <video/mipi_display.h>

+#include <drm/drm_mipi_dsi.h> +#include <drm/drm_modes.h> +#include <drm/drm_panel.h> +#include <drm/drm_print.h>

+struct nt35521_panel {

• struct drm_panel panel;
• struct device *dev;
• struct gpio_desc *rst_gpio;
• struct gpio_desc *pwrp5_gpio;
• struct gpio_desc *pwrn5_gpio;
• struct gpio_desc *en_gpio;
• bool prepared;
• bool enabled;

+};

+static inline struct nt35521_panel *panel_to_nt35521(struct drm_panel *panel) +{

• return container_of(panel, struct nt35521_panel, panel);

+}

+#define nt_dcs_write(seq...) \ +({ \

• const u8 d[] = { seq }; \
• if (mipi_dsi_dcs_write_buffer(dsi, d, ARRAY_SIZE(d)) < 0) \

• DRM_DEV_ERROR(dev, "dcs write buffer failed\n");	\
  

+})

+#define nt_gen_write(seq...) \ +({ \

• const u8 d[] = { seq }; \
• if (mipi_dsi_generic_write(dsi, d, ARRAY_SIZE(d)) < 0) \

• DRM_DEV_ERROR(dev, "generic write buffer failed\n");	\
  

+})

+static void nt35521_panel_on(struct nt35521_panel *nt) +{

• struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
• struct device *dev = nt->dev;
• /* Transmit data in low power mode */
• dsi->mode_flags |= MIPI_DSI_MODE_LPM;
• nt_dcs_write(0xf0, 0x55, 0xaa, 0x52, 0x08, 0x00);
• nt_dcs_write(0xff, 0xaa, 0x55, 0xa5, 0x80);
• nt_dcs_write(0x6f, 0x11, 0x00);
• nt_dcs_write(0xf7, 0x20, 0x00);
• nt_dcs_write(0x6f, 0x01);
• nt_dcs_write(0xb1, 0x21);
• nt_dcs_write(0xbd, 0x01, 0xa0, 0x10, 0x08, 0x01);
• nt_dcs_write(0xb8, 0x01, 0x02, 0x0c, 0x02);
• nt_dcs_write(0xbb, 0x11, 0x11);
• nt_dcs_write(0xbc, 0x00, 0x00);
• nt_dcs_write(0xb6, 0x02);
• nt_dcs_write(0xf0, 0x55, 0xaa, 0x52, 0x08, 0x01);
• nt_dcs_write(0xb0, 0x09, 0x09);
• nt_dcs_write(0xb1, 0x09, 0x09);
• nt_dcs_write(0xbc, 0x8c, 0x00);
• nt_dcs_write(0xbd, 0x8c, 0x00);
• nt_dcs_write(0xca, 0x00);
• nt_dcs_write(0xc0, 0x04);
• nt_dcs_write(0xbe, 0xb5);
• nt_dcs_write(0xb3, 0x35, 0x35);
• nt_dcs_write(0xb4, 0x25, 0x25);
• nt_dcs_write(0xb9, 0x43, 0x43);
• nt_dcs_write(0xba, 0x24, 0x24);
• nt_dcs_write(0xf0, 0x55, 0xaa, 0x52, 0x08, 0x02);
• nt_dcs_write(0xee, 0x03);
• nt_dcs_write(0xb0, 0x00, 0xb2, 0x00, 0xb3, 0x00, 0xb6, 0x00,

•      0xc3, 0x00, 0xce, 0x00, 0xe1, 0x00, 0xf3, 0x01,
  

•      0x11);
  

• nt_dcs_write(0xb1, 0x01, 0x2e, 0x01, 0x5c, 0x01, 0x82, 0x01,

•      0xc3, 0x01, 0xfe, 0x02, 0x00, 0x02, 0x37, 0x02,
  

•      0x77);
  

• nt_dcs_write(0xb2, 0x02, 0xa1, 0x02, 0xd7, 0x02, 0xfe, 0x03,

•      0x2c, 0x03, 0x4b, 0x03, 0x63, 0x03, 0x8f, 0x03,
  

•      0x90);
  

• nt_dcs_write(0xb3, 0x03, 0x96, 0x03, 0x98);
• nt_dcs_write(0xb4, 0x00, 0x81, 0x00, 0x8b, 0x00, 0x9c, 0x00,

•      0xa9, 0x00, 0xb5, 0x00, 0xcb, 0x00, 0xdf, 0x01,
  

•      0x02);
  

• nt_dcs_write(0xb5, 0x01, 0x1f, 0x01, 0x51, 0x01, 0x7a, 0x01,

•      0xbf, 0x01, 0xfa, 0x01, 0xfc, 0x02, 0x34, 0x02, 0x76);
  

• nt_dcs_write(0xb6, 0x02, 0x9f, 0x02, 0xd7, 0x02, 0xfc, 0x03, 0x2c,

•      0x03, 0x4a, 0x03, 0x63, 0x03, 0x8f, 0x03, 0xa2);
  

• nt_dcs_write(0xb7, 0x03, 0xb8, 0x03, 0xba);
• nt_dcs_write(0xb8, 0x00, 0x01, 0x00, 0x02, 0x00, 0x0e, 0x00, 0x2a,

•      0x00, 0x41, 0x00, 0x67, 0x00, 0x87, 0x00, 0xb9);
  

• nt_dcs_write(0xb9, 0x00, 0xe2, 0x01, 0x22, 0x01, 0x54, 0x01, 0xa3,

•      0x01, 0xe6, 0x01, 0xe7, 0x02, 0x24, 0x02, 0x67);
  

• nt_dcs_write(0xba, 0x02, 0x93, 0x02, 0xcd, 0x02, 0xf6, 0x03, 0x31,

•      0x03, 0x6c, 0x03, 0xe9, 0x03, 0xef, 0x03, 0xf4);
  

• nt_dcs_write(0xbb, 0x03, 0xf6, 0x03, 0xf7);
• nt_dcs_write(0xf0, 0x55, 0xaa, 0x52, 0x08, 0x03);
• nt_dcs_write(0xb0, 0x22, 0x00);
• nt_dcs_write(0xb1, 0x22, 0x00);
• nt_dcs_write(0xb2, 0x05, 0x00, 0x60, 0x00, 0x00);
• nt_dcs_write(0xb3, 0x05, 0x00, 0x60, 0x00, 0x00);
• nt_dcs_write(0xb4, 0x05, 0x00, 0x60, 0x00, 0x00);
• nt_dcs_write(0xb5, 0x05, 0x00, 0x60, 0x00, 0x00);
• nt_dcs_write(0xba, 0x53, 0x00, 0x60, 0x00, 0x00);
• nt_dcs_write(0xbb, 0x53, 0x00, 0x60, 0x00, 0x00);
• nt_dcs_write(0xbc, 0x53, 0x00, 0x60, 0x00, 0x00);
• nt_dcs_write(0xbd, 0x53, 0x00, 0x60, 0x00, 0x00);
• nt_dcs_write(0xc0, 0x00, 0x34, 0x00, 0x00);
• nt_dcs_write(0xc1, 0x00, 0x00, 0x34, 0x00);
• nt_dcs_write(0xc2, 0x00, 0x00, 0x34, 0x00);
• nt_dcs_write(0xc3, 0x00, 0x00, 0x34, 0x00);
• nt_dcs_write(0xc4, 0x60);
• nt_dcs_write(0xc5, 0xc0);
• nt_dcs_write(0xc6, 0x00);
• nt_dcs_write(0xc7, 0x00);
• nt_dcs_write(0xf0, 0x55, 0xaa, 0x52, 0x08, 0x05);
• nt_dcs_write(0xb0, 0x17, 0x06);
• nt_dcs_write(0xb1, 0x17, 0x06);
• nt_dcs_write(0xb2, 0x17, 0x06);
• nt_dcs_write(0xb3, 0x17, 0x06);
• nt_dcs_write(0xb4, 0x17, 0x06);
• nt_dcs_write(0xb5, 0x17, 0x06);
• nt_dcs_write(0xb6, 0x17, 0x06);
• nt_dcs_write(0xb7, 0x17, 0x06);
• nt_dcs_write(0xb8, 0x00);
• nt_dcs_write(0xb9, 0x00, 0x03);
• nt_dcs_write(0xba, 0x00, 0x00);
• nt_dcs_write(0xbb, 0x02, 0x03);
• nt_dcs_write(0xbc, 0x02, 0x03);
• nt_dcs_write(0xbd, 0x03, 0x03, 0x00, 0x03, 0x03);
• nt_dcs_write(0xc0, 0x0b);
• nt_dcs_write(0xc1, 0x09);
• nt_dcs_write(0xc2, 0xa6);
• nt_dcs_write(0xc3, 0x05);
• nt_dcs_write(0xc4, 0x00);
• nt_dcs_write(0xc5, 0x02);
• nt_dcs_write(0xc6, 0x22);
• nt_dcs_write(0xc7, 0x03);
• nt_dcs_write(0xc8, 0x07, 0x20);
• nt_dcs_write(0xc9, 0x03, 0x20);
• nt_dcs_write(0xca, 0x01, 0x60);
• nt_dcs_write(0xcb, 0x01, 0x60);
• nt_dcs_write(0xcc, 0x00, 0x00, 0x02);
• nt_dcs_write(0xcd, 0x00, 0x00, 0x02);
• nt_dcs_write(0xce, 0x00, 0x00, 0x02);
• nt_dcs_write(0xcf, 0x00, 0x00, 0x02);
• nt_dcs_write(0xd1, 0x00, 0x05, 0x01, 0x07, 0x10);
• nt_dcs_write(0xd2, 0x10, 0x05, 0x05, 0x03, 0x10);
• nt_dcs_write(0xd3, 0x20, 0x00, 0x43, 0x07, 0x10);
• nt_dcs_write(0xd4, 0x30, 0x00, 0x43, 0x07, 0x10);
• nt_dcs_write(0xd0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00);
• nt_dcs_write(0xd5, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

•      0x00, 0x00, 0x00, 0x00);
  

• nt_dcs_write(0xd6, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

•      0x00, 0x00, 0x00, 0x00);
  

• nt_dcs_write(0xd7, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

•      0x00, 0x00, 0x00, 0x00);
  

• nt_dcs_write(0xd8, 0x00, 0x00, 0x00, 0x00, 0x00);
• nt_dcs_write(0xe5, 0x06);
• nt_dcs_write(0xe6, 0x06);
• nt_dcs_write(0xe7, 0x00);
• nt_dcs_write(0xe8, 0x06);
• nt_dcs_write(0xe9, 0x06);
• nt_dcs_write(0xea, 0x06);
• nt_dcs_write(0xeb, 0x00);
• nt_dcs_write(0xec, 0x00);
• nt_dcs_write(0xed, 0x30);
• nt_dcs_write(0xf0, 0x55, 0xaa, 0x52, 0x08, 0x06);
• nt_dcs_write(0xb0, 0x31, 0x31);
• nt_dcs_write(0xb1, 0x31, 0x31);
• nt_dcs_write(0xb2, 0x2d, 0x2e);
• nt_dcs_write(0xb3, 0x31, 0x34);
• nt_dcs_write(0xb4, 0x29, 0x2a);
• nt_dcs_write(0xb5, 0x12, 0x10);
• nt_dcs_write(0xb6, 0x18, 0x16);
• nt_dcs_write(0xb7, 0x00, 0x02);
• nt_dcs_write(0xb8, 0x08, 0x31);
• nt_dcs_write(0xb9, 0x31, 0x31);
• nt_dcs_write(0xba, 0x31, 0x31);
• nt_dcs_write(0xbb, 0x31, 0x08);
• nt_dcs_write(0xbc, 0x03, 0x01);
• nt_dcs_write(0xbd, 0x17, 0x19);
• nt_dcs_write(0xbe, 0x11, 0x13);
• nt_dcs_write(0xbf, 0x2a, 0x29);
• nt_dcs_write(0xc0, 0x34, 0x31);
• nt_dcs_write(0xc1, 0x2e, 0x2d);
• nt_dcs_write(0xc2, 0x31, 0x31);
• nt_dcs_write(0xc3, 0x31, 0x31);
• nt_dcs_write(0xc4, 0x31, 0x31);
• nt_dcs_write(0xc5, 0x31, 0x31);
• nt_dcs_write(0xc6, 0x2e, 0x2d);
• nt_dcs_write(0xc7, 0x31, 0x34);
• nt_dcs_write(0xc8, 0x29, 0x2a);
• nt_dcs_write(0xc9, 0x17, 0x19);
• nt_dcs_write(0xca, 0x11, 0x13);
• nt_dcs_write(0xcb, 0x03, 0x01);
• nt_dcs_write(0xcc, 0x08, 0x31);
• nt_dcs_write(0xcd, 0x31, 0x31);
• nt_dcs_write(0xce, 0x31, 0x31);
• nt_dcs_write(0xcf, 0x31, 0x08);
• nt_dcs_write(0xd0, 0x00, 0x02);
• nt_dcs_write(0xd1, 0x12, 0x10);
• nt_dcs_write(0xd2, 0x18, 0x16);
• nt_dcs_write(0xd3, 0x2a, 0x29);
• nt_dcs_write(0xd4, 0x34, 0x31);
• nt_dcs_write(0xd5, 0x2d, 0x2e);
• nt_dcs_write(0xd6, 0x31, 0x31);
• nt_dcs_write(0xd7, 0x31, 0x31);
• nt_dcs_write(0xe5, 0x31, 0x31);
• nt_dcs_write(0xe6, 0x31, 0x31);
• nt_dcs_write(0xd8, 0x00, 0x00, 0x00, 0x00, 0x00);
• nt_dcs_write(0xd9, 0x00, 0x00, 0x00, 0x00, 0x00);
• nt_dcs_write(0xe7, 0x00);
• nt_dcs_write(0x6f, 0x02);
• nt_dcs_write(0xf7, 0x47);
• nt_dcs_write(0x6f, 0x0a);
• nt_dcs_write(0xf7, 0x02);
• nt_dcs_write(0x6f, 0x17);
• nt_dcs_write(0xf4, 0x60);
• nt_dcs_write(0x6f, 0x01);
• nt_dcs_write(0xf9, 0x46);
• nt_dcs_write(0x6f, 0x11);
• nt_dcs_write(0xf3, 0x01);
• nt_dcs_write(0x35, 0x00);
• nt_dcs_write(0xf0, 0x55, 0xaa, 0x52, 0x08, 0x00);
• nt_dcs_write(0xd9, 0x02, 0x03, 0x00);
• nt_dcs_write(0xf0, 0x55, 0xaa, 0x52, 0x00, 0x00);
• nt_dcs_write(0xf0, 0x55, 0xaa, 0x52, 0x08, 0x00);
• nt_dcs_write(0xb1, 0x6c, 0x21);
• nt_dcs_write(0xf0, 0x55, 0xaa, 0x52, 0x00, 0x00);
• nt_dcs_write(0x35, 0x00);
• nt_gen_write(0x11, 0x00);
• msleep(120);
• nt_gen_write(0x29, 0x00);
• usleep_range(1000, 1500);
• nt_dcs_write(0x53, 0x24);

Did you mix up "nt_dcs_write" and "nt_gen_write" here? The nt_gen_write(0x11, 0x00); looks like MIPI_DCS_EXIT_SLEEP_MODE and the nt_gen_write(0x29, 0x00); looks like MIPI_DCS_SET_DISPLAY_ON.

For reference you can pull your original reference DTB from Sony through my panel driver generator: https://github.com/msm8916-mainline/linux-mdss-dsi-panel-driver-generator

It produces the following (I compiled "msm8939-kanuti_tulip.dtb" from https://github.com/sonyxperiadev/kernel/tree/aosp/LA.BR.1.3.3_rb2.14, not sure if that is right):

// ... dsi_generic_write_seq(dsi, 0x35, 0x00);

ret = mipi_dsi_dcs_exit_sleep_mode(dsi); if (ret < 0) { dev_err(dev, "Failed to exit sleep mode: %d\n", ret); return ret; } msleep(120);

ret = mipi_dsi_dcs_set_display_on(dsi); if (ret < 0) { dev_err(dev, "Failed to set display on: %d\n", ret); return ret; } usleep_range(1000, 2000);

dsi_generic_write_seq(dsi, 0x53, 0x24);

Which also suggests that generic and DCS writes are mixed up here.

Note however that you could not use the generated driver as-is, because Sony seems to use their own display driver instead of Qualcomm's and some things seem to be different.

+}

+static void nt35521_panel_off(struct nt35521_panel *nt) +{

• struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
• struct device *dev = nt->dev;
• /* Transmit data in high speed mode */
• dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
• nt_dcs_write(0x28, 0x00);
• msleep(50);
• nt_dcs_write(0x10, 0x00);
• msleep(150);

A bit more deobfuscated from the panel driver generator:

dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;

ret = mipi_dsi_dcs_set_display_off(dsi); if (ret < 0) { dev_err(dev, "Failed to set display off: %d\n", ret); return ret; } msleep(50);

ret = mipi_dsi_dcs_enter_sleep_mode(dsi); if (ret < 0) { dev_err(dev, "Failed to enter sleep mode: %d\n", ret); return ret; } msleep(150);

(I'm mainly referring to the mipi_dsi_dcs_*() here instead of the magic numbers...)

+}

+static int nt35521_prepare(struct drm_panel *panel) +{

• struct nt35521_panel *nt = panel_to_nt35521(panel);
• if (nt->prepared)

• return 0;
  

• gpiod_set_value_cansleep(nt->pwrp5_gpio, 1);
• usleep_range(1000, 1500);
• gpiod_set_value_cansleep(nt->pwrn5_gpio, 1);
• usleep_range(10000, 15000);
• gpiod_set_value_cansleep(nt->rst_gpio, 0);
• msleep(150);
• nt35521_panel_on(nt);
• nt->prepared = true;
• return 0;

+}

+static int nt35521_unprepare(struct drm_panel *panel) +{

• struct nt35521_panel *nt = panel_to_nt35521(panel);
• if (!nt->prepared)

• return 0;
  

• nt35521_panel_off(nt);
• gpiod_set_value_cansleep(nt->rst_gpio, 1);
• nt->prepared = false;
• return 0;

+}

+static int nt35521_enable(struct drm_panel *panel) +{

• struct nt35521_panel *nt = panel_to_nt35521(panel);
• if (nt->enabled)

• return 0;
  

• gpiod_set_value_cansleep(nt->en_gpio, 1);
• nt->enabled = true;
• return 0;

+}

+static int nt35521_disable(struct drm_panel *panel) +{

• struct nt35521_panel *nt = panel_to_nt35521(panel);
• if (!nt->enabled)

• return 0;
  

• gpiod_set_value_cansleep(nt->en_gpio, 0);
• nt->enabled = false;
• return 0;

+}

+static const struct drm_display_mode nt35521_modes = {

• .clock = 133306,
• .hdisplay = 720,
• .hsync_start = 720 + 632,
• .hsync_end = 720 + 632 + 40,
• .htotal = 720 + 632 + 40 + 295,
• .vdisplay = 1280,
• .vsync_start = 1280 + 18,
• .vsync_end = 1280 + 18 + 1,
• .vtotal = 1280 + 18 + 1 + 18,

+};

+static int nt35521_get_modes(struct drm_panel *panel,

• 	      struct drm_connector *connector)
  

+{

• struct nt35521_panel *nt = panel_to_nt35521(panel);
• struct drm_display_mode *mode;
• mode = drm_mode_duplicate(connector->dev, &nt35521_modes);
• if (!mode) {

• DRM_DEV_ERROR(nt->dev, "failed to add display mode\n");
  

• return -ENOMEM;
  

• }
• drm_mode_set_name(mode);
• drm_mode_probed_add(connector, mode);
• connector->display_info.width_mm = 65;
• connector->display_info.height_mm = 116;
• return 1;

+}

+static const struct drm_panel_funcs nt35521_drm_funcs = {

• .prepare = nt35521_prepare,
• .unprepare = nt35521_unprepare,
• .enable = nt35521_enable,
• .disable = nt35521_disable,
• .get_modes = nt35521_get_modes,

+};

+static int nt35521_backlight_update_status(struct backlight_device *bd) +{

• struct nt35521_panel *nt = bl_get_data(bd);
• struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
• u8 brightness = bd->props.brightness;

u8 brightness = backlight_get_brightness(bl);

Is preferred now I think(?).

• int ret;
• ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,

• 		 &brightness,
  

• 		 sizeof(brightness));
  

Does this work too?

ret = mipi_dsi_dcs_set_display_brightness(dsi, brightness);

• if (ret < 0)

• return ret;
  

• return 0;

+}

+static const struct backlight_ops nt35521_backlight_ops = {

• .update_status = nt35521_backlight_update_status,

+};

+static int nt35521_probe(struct mipi_dsi_device *dsi) +{

• struct backlight_properties props;
• struct device *dev = &dsi->dev;
• struct nt35521_panel *nt;
• int ret;
• nt = devm_kzalloc(dev, sizeof(*nt), GFP_KERNEL);
• if (!nt)

• return -ENOMEM;
  

• nt->rst_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
• if (IS_ERR(nt->rst_gpio)) {

• ret = PTR_ERR(nt->rst_gpio);
  

• DRM_DEV_ERROR(dev, "failed to get reset GPIO: %d\n", ret);
  

• return ret;
  

• }
• nt->pwrp5_gpio = devm_gpiod_get(dev, "pwr-positive5", GPIOD_OUT_LOW);
• if (IS_ERR(nt->pwrp5_gpio)) {

• ret = PTR_ERR(nt->pwrp5_gpio);
  

• DRM_DEV_ERROR(dev, "failed to get positive5 GPIO: %d\n", ret);
  

• return ret;
  

• }
• nt->pwrn5_gpio = devm_gpiod_get(dev, "pwr-negative5", GPIOD_OUT_LOW);
• if (IS_ERR(nt->pwrn5_gpio)) {

• ret = PTR_ERR(nt->pwrn5_gpio);
  

• DRM_DEV_ERROR(dev, "failed to get negative5 GPIO: %d\n", ret);
  

• return ret;
  

• }

These two GPIOs look a lot like typical 5V display regulators that would be better described through the regulator subsystem. You can declare them as fixed-regulator to toggle the GPIO.

• nt->en_gpio = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
• if (IS_ERR(nt->en_gpio)) {

• ret = PTR_ERR(nt->en_gpio);
  

• DRM_DEV_ERROR(dev, "failed to get enable GPIO: %d\n", ret);
  

• return ret;
  

• }

Does this refer to the "platform-bklight-en-gpio" in the Sony sources? Perhaps calling it "backlight-gpios" or something like that would be more clear to show that it's related to the backlight.

Thanks! Stephan