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From: Sam Ravnborg <sam@ravnborg.org>
To: Markuss Broks <markuss.broks@gmail.com>
Cc: linux-kernel@vger.kernel.org, linus.walleij@linaro.org,
 phone-devel@vger.kernel.org, Thierry Reding <thierry.reding@gmail.com>,
 David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
 Rob Herring <robh+dt@kernel.org>, dri-devel@lists.freedesktop.org,
 devicetree@vger.kernel.org
Subject: Re: [PATCH 2/2] drm/panel: s6d27a1: Add driver for Samsung S6D27A1
 display panel
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References: <YQmG6EbBherV+8px@ravnborg.org>
 <20210805133343.27032-1-markuss.broks@gmail.com>
 <20210805133343.27032-3-markuss.broks@gmail.com>
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Hi Markuss,

On Thu, Aug 05, 2021 at 04:33:42PM +0300, Markuss Broks wrote:
> This adds a driver for Samsung S6D27A1 display controller and panel.
> This panel is found in the Samsung GT-I8160 mobile phone,
> and possibly some other mobile phones.
> 
> This display needs manufacturer commands to configure it;
> the commands used in this driver were taken from downstream driver
> by Gareth Phillips; sadly, there is almost no documentation on what they
> actually do.
> 
> This driver re-uses the DBI infrastructure to communicate with the display.
> 
> This driver is heavily based on WideChips WS2401 display controller
> driver by Linus Walleij and on other panel drivers for reference.
> 
> Signed-off-by: Markuss Broks <markuss.broks@gmail.com>
> 
> v2 -> v3:
> fixed checkpatch warnings - not sure about MAINTAINERS, should I
> put my name up there?
You made lots of other changes..

Yes, MAINTAINERS would be great so you get mails when something is
updated. This allows you to verify refactoring changes or bug fixes for
example.

For a single driver you can realy on someone else to apply patches, no
need to deal with drm-misc etc. for that.

A few details in the following, but driver is almost there.

	Sam


> ---
>  drivers/gpu/drm/panel/Kconfig                 |  11 +
>  drivers/gpu/drm/panel/Makefile                |   1 +
>  drivers/gpu/drm/panel/panel-samsung-s6d27a1.c | 323 ++++++++++++++++++
>  3 files changed, 335 insertions(+)
>  create mode 100644 drivers/gpu/drm/panel/panel-samsung-s6d27a1.c
> 
> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> index beb581b96e..0b37849413 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -392,6 +392,17 @@ config DRM_PANEL_SAMSUNG_S6D16D0
>  	depends on DRM_MIPI_DSI
>  	select VIDEOMODE_HELPERS
>  
> +config DRM_PANEL_SAMSUNG_S6D27A1
> +	tristate "Samsung S6D27A1 DPI panel driver"
> +	depends on OF && SPI && GPIOLIB
> +	select DRM_MIPI_DBI
> +	help
> +	  Say Y here if you want to enable support for the Samsung
> +	  S6D27A1 DPI 480x800 panel.
> +
> +	  This panel can be found in Samsung Galaxy Ace 2
> +	  GT-I8160 mobile phone.
> +
>  config DRM_PANEL_SAMSUNG_S6E3HA2
>  	tristate "Samsung S6E3HA2 DSI video mode panel"
>  	depends on OF
> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
> index c8132050bc..60c0149fc5 100644
> --- a/drivers/gpu/drm/panel/Makefile
> +++ b/drivers/gpu/drm/panel/Makefile
> @@ -39,6 +39,7 @@ obj-$(CONFIG_DRM_PANEL_SAMSUNG_ATNA33XC20) += panel-samsung-atna33xc20.o
>  obj-$(CONFIG_DRM_PANEL_SAMSUNG_DB7430) += panel-samsung-db7430.o
>  obj-$(CONFIG_DRM_PANEL_SAMSUNG_LD9040) += panel-samsung-ld9040.o
>  obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6D16D0) += panel-samsung-s6d16d0.o
> +obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6D27A1) += panel-samsung-s6d27a1.o
>  obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E3HA2) += panel-samsung-s6e3ha2.o
>  obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E63J0X03) += panel-samsung-s6e63j0x03.o
>  obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E63M0) += panel-samsung-s6e63m0.o
> diff --git a/drivers/gpu/drm/panel/panel-samsung-s6d27a1.c b/drivers/gpu/drm/panel/panel-samsung-s6d27a1.c
> new file mode 100644
> index 0000000000..6a77a15136
> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-samsung-s6d27a1.c
> @@ -0,0 +1,323 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Panel driver for the Samsung S6D27A1 480x800 DPI RGB panel.
> + * Found in the Samsung Galaxy Ace 2 GT-I8160 mobile phone.
> + */
> +
> +#include <drm/drm_modes.h>
> +#include <drm/drm_mipi_dbi.h>
> +#include <drm/drm_panel.h>
> +
> +#include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/media-bus-format.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/spi/spi.h>
> +
> +#include <video/mipi_display.h>
> +
> +#define S6D27A1_PASSWD_L2	0xF0	/* Password Command for Level 2 Control */
> +#define S6D27A1_RESCTL		0xB3	/* Resolution Select Control */
> +#define S6D27A1_PANELCTL2	0xB4	/* ASG Signal Control */
> +#define S6D27A1_READID1		0xDA	/* Read panel ID 1 */
> +#define S6D27A1_READID2		0xDB	/* Read panel ID 2 */
> +#define S6D27A1_READID3		0xDC	/* Read panel ID 3 */
> +#define S6D27A1_DISPCTL		0xF2	/* Display Control */
> +#define S6D27A1_MANPWR		0xF3	/* Manual Control */
> +#define S6D27A1_PWRCTL1		0xF4	/* Power Control */
> +#define S6D27A1_SRCCTL		0xF6	/* Source Control */
> +#define S6D27A1_PANELCTL	0xF7	/* Panel Control*/
> +
> +static const u8 s6d27a1_dbi_read_commands[] = {
> +	S6D27A1_READID1,
> +	S6D27A1_READID2,
> +	S6D27A1_READID3,
> +	0, /* sentinel */
> +};
> +
> +struct s6d27a1 {
> +	struct device *dev;
> +	struct mipi_dbi dbi;
> +	struct drm_panel panel;
> +	struct gpio_desc *reset;
> +	struct regulator_bulk_data regulators[2];
> +};
> +
> +static const struct drm_display_mode s6d27a1_480_800_mode = {
> +	/*
> +	 * The vendor driver states that the S6D27A1 panel
> +	 * has a pixel clock frequency of 49920000 Hz / 2 = 24960000 Hz.
> +	 */
> +	.clock = 24960,
> +	.hdisplay = 480,
> +	.hsync_start = 480 + 63,
> +	.hsync_end = 480 + 63 + 2,
> +	.htotal = 480 + 63 + 2 + 63,
> +	.vdisplay = 800,
> +	.vsync_start = 800 + 11,
> +	.vsync_end = 800 + 11 + 2,
> +	.vtotal = 800 + 11 + 2 + 10,
> +	.width_mm = 50,
> +	.height_mm = 84,
> +	.flags = DRM_MODE_FLAG_NVSYNC | DRM_MODE_FLAG_NHSYNC,
> +};
> +
> +static inline struct s6d27a1 *to_s6d27a1(struct drm_panel *panel)
> +{
> +	return container_of(panel, struct s6d27a1, panel);
> +}
> +
> +#define s6d27a1_command(ctx, cmd, seq...) \
> +({ \
> +	struct mipi_dbi *dbi = &ctx->dbi; \
> +	int ret; \
> +	ret = mipi_dbi_command(dbi, cmd, seq);	\
> +	if (ret) { \
> +		dev_err(ctx->dev, "failure in writing command %02x\n", cmd); \
> +	} \
> +})
This does not error out like other panel drivers. I think this is
wrong.

> +
> +static void s6d27a1_read_mtp_id(struct s6d27a1 *ctx)
> +{
> +	struct mipi_dbi *dbi = &ctx->dbi;
> +	u8 id1, id2, id3;
> +	int ret;
> +
> +	ret = mipi_dbi_command_read(dbi, S6D27A1_READID1, &id1);
> +	if (ret) {
> +		dev_err(ctx->dev, "unable to read MTP ID 1\n");
> +		return;
> +	}
> +	ret = mipi_dbi_command_read(dbi, S6D27A1_READID2, &id2);
> +	if (ret) {
> +		dev_err(ctx->dev, "unable to read MTP ID 2\n");
> +		return;
> +	}
> +	ret = mipi_dbi_command_read(dbi, S6D27A1_READID3, &id3);
> +	if (ret) {
> +		dev_err(ctx->dev, "unable to read MTP ID 3\n");
> +		return;
> +	}
> +	dev_info(ctx->dev, "MTP ID: %02x %02x %02x\n", id1, id2, id3);
> +}
> +
> +static int s6d27a1_power_on(struct s6d27a1 *ctx)
> +{
> +	int ret;
> +
> +	/* Power up */
> +	ret = regulator_bulk_enable(ARRAY_SIZE(ctx->regulators),
> +				    ctx->regulators);
> +	if (ret) {
> +		dev_err(ctx->dev, "failed to enable regulators: %d\n", ret);
> +		return ret;
> +	}
> +
> +	msleep(20);
> +
> +	/* Assert reset >=1 ms */
> +	gpiod_set_value_cansleep(ctx->reset, 1);
> +	usleep_range(1000, 5000);
> +	/* De-assert reset */
> +	gpiod_set_value_cansleep(ctx->reset, 0);
> +	/* Wait >= 10 ms */
> +	msleep(20);
> +
> +	/*
> +	 * Exit sleep mode and initialize display - some hammering is
> +	 * necessary.
> +	 */
> +	s6d27a1_command(ctx, MIPI_DCS_EXIT_SLEEP_MODE);
> +	s6d27a1_command(ctx, MIPI_DCS_EXIT_SLEEP_MODE);
> +	msleep(50);
> +
> +	/* Magic to unlock level 2 control of the display */
> +	s6d27a1_command(ctx, S6D27A1_PASSWD_L2, 0x5A, 0x5A);
> +
> +	/* Configure resolution to 480RGBx800 */
> +	s6d27a1_command(ctx, S6D27A1_RESCTL, 0x22);
> +
> +	s6d27a1_command(ctx, S6D27A1_PANELCTL2, 0x00, 0x02, 0x03, 0x04, 0x05, 0x08, 0x00, 0x0c);
> +
> +	s6d27a1_command(ctx, S6D27A1_MANPWR, 0x01, 0x00, 0x00, 0x08, 0x08, 0x02, 0x00);
> +
> +	s6d27a1_command(ctx, S6D27A1_DISPCTL, 0x19, 0x00, 0x08, 0x0D, 0x03, 0x41, 0x3F);
> +
> +	s6d27a1_command(ctx, S6D27A1_PWRCTL1, 0x00, 0x00, 0x00, 0x00, 0x55,
> +					0x44, 0x05, 0x88, 0x4B, 0x50);
> +
> +	s6d27a1_command(ctx, S6D27A1_SRCCTL, 0x03, 0x09, 0x8A, 0x00, 0x01, 0x16);
> +
> +	s6d27a1_command(ctx, S6D27A1_PANELCTL, 0x00, 0x05, 0x06, 0x07, 0x08,
> +					0x01, 0x09, 0x0D, 0x0A, 0x0E,
> +					0x0B, 0x0F, 0x0C, 0x10, 0x01,
> +					0x11, 0x12, 0x13, 0x14, 0x05,
> +					0x06, 0x07, 0x08, 0x01, 0x09,
> +					0x0D, 0x0A, 0x0E, 0x0B, 0x0F,
> +					0x0C, 0x10, 0x01, 0x11, 0x12,
> +					0x13, 0x14);
> +
> +	/* lock the level 2 control */
> +	s6d27a1_command(ctx, S6D27A1_PASSWD_L2, 0xA5, 0xA5);
> +
> +	s6d27a1_read_mtp_id(ctx);
> +
> +	return 0;
> +}
> +
> +static int s6d27a1_power_off(struct s6d27a1 *ctx)
> +{
> +	/* Go into RESET and disable regulators */
> +	gpiod_set_value_cansleep(ctx->reset, 1);
> +	return regulator_bulk_disable(ARRAY_SIZE(ctx->regulators),
> +				      ctx->regulators);
> +}
> +
> +static int s6d27a1_unprepare(struct drm_panel *panel)
> +{
> +	struct s6d27a1 *ctx = to_s6d27a1(panel);
> +
> +	s6d27a1_command(ctx, MIPI_DCS_ENTER_SLEEP_MODE);
> +	msleep(120);
> +	return s6d27a1_power_off(to_s6d27a1(panel));
> +}
> +
> +static int s6d27a1_disable(struct drm_panel *panel)
> +{
> +	struct s6d27a1 *ctx = to_s6d27a1(panel);
> +
> +	s6d27a1_command(ctx, MIPI_DCS_SET_DISPLAY_OFF);
> +	msleep(25);
> +
> +	return 0;
> +}
> +
> +static int s6d27a1_prepare(struct drm_panel *panel)
> +{
> +	return s6d27a1_power_on(to_s6d27a1(panel));
> +}
> +
> +static int s6d27a1_enable(struct drm_panel *panel)
> +{
> +	struct s6d27a1 *ctx = to_s6d27a1(panel);
> +
> +	s6d27a1_command(ctx, MIPI_DCS_SET_DISPLAY_ON);
> +
> +	return 0;
> +}
> +
> +static int s6d27a1_get_modes(struct drm_panel *panel,
> +			    struct drm_connector *connector)
> +{
> +	struct s6d27a1 *ctx = to_s6d27a1(panel);
> +	struct drm_display_mode *mode;
> +	static const u32 bus_format = MEDIA_BUS_FMT_RGB888_1X24;
> +
> +	mode = drm_mode_duplicate(connector->dev, &s6d27a1_480_800_mode);
> +	if (!mode) {
> +		dev_err(ctx->dev, "failed to add mode\n");
> +		return -ENOMEM;
> +	}
> +
> +	connector->display_info.bpc = 8;
> +	connector->display_info.width_mm = mode->width_mm;
> +	connector->display_info.height_mm = mode->height_mm;
> +	connector->display_info.bus_flags =
> +		DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE;
> +	drm_display_info_set_bus_formats(&connector->display_info,
> +					 &bus_format, 1);
> +
> +	drm_mode_set_name(mode);
> +	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
> +
> +	drm_mode_probed_add(connector, mode);
> +
> +	return 1;
> +}
> +
> +static const struct drm_panel_funcs s6d27a1_drm_funcs = {
> +	.disable = s6d27a1_disable,
> +	.unprepare = s6d27a1_unprepare,
> +	.prepare = s6d27a1_prepare,
> +	.enable = s6d27a1_enable,
> +	.get_modes = s6d27a1_get_modes,
> +};
> +
> +static int s6d27a1_probe(struct spi_device *spi)
> +{
> +	struct device *dev = &spi->dev;
> +	struct s6d27a1 *ctx;
> +	int ret;
> +
> +	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
> +	if (!ctx)
> +		return -ENOMEM;
> +
> +	ctx->dev = dev;
> +
> +	/*
> +	 * VCI   is the analog voltage supply
> +	 * VCCIO is the digital I/O voltage supply
> +	 */
> +	ctx->regulators[0].supply = "vci";
> +	ctx->regulators[1].supply = "vccio";
> +	ret = devm_regulator_bulk_get(dev,
> +				      ARRAY_SIZE(ctx->regulators),
> +				      ctx->regulators);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to get regulators\n");
> +
> +	ctx->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(ctx->reset)) {
> +		ret = PTR_ERR(ctx->reset);
> +		return dev_err_probe(dev, ret, "no RESET GPIO\n");
> +	}
> +
> +	ret = mipi_dbi_spi_init(spi, &ctx->dbi, NULL);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "MIPI DBI init failed\n");
> +
> +	ctx->dbi.read_commands = s6d27a1_dbi_read_commands;
> +
> +	drm_panel_init(&ctx->panel, dev, &s6d27a1_drm_funcs,
> +		       DRM_MODE_CONNECTOR_DPI);
> +
> +	spi_set_drvdata(spi, ctx);
> +
> +	drm_panel_add(&ctx->panel);
> +	dev_dbg(dev, "added panel\n");
Debug leftover that can be dropped.
> +
> +	return 0;
> +}
> +
> +static int s6d27a1_remove(struct spi_device *spi)
> +{
> +	struct s6d27a1 *ctx = spi_get_drvdata(spi);
> +
> +	drm_panel_remove(&ctx->panel);
> +	return 0;
> +}
> +
> +static const struct of_device_id s6d27a1_match[] = {
> +	{ .compatible = "samsung,s6d27a1", },
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, s6d27a1_match);
> +
> +static struct spi_driver s6d27a1_driver = {
> +	.probe		= s6d27a1_probe,
> +	.remove		= s6d27a1_remove,
> +	.driver		= {
> +		.name	= "s6d27a1-panel",
> +		.of_match_table = s6d27a1_match,
> +	},
> +};
> +module_spi_driver(s6d27a1_driver);
> +
> +MODULE_AUTHOR("Markuss Broks <markuss.broks@gmail.com>");
> +MODULE_DESCRIPTION("Samsung S6D27A1 panel driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.32.0