Date:   Wed, 20 Sep 2017 12:18:05 -0700
From:   Sean Paul <seanpaul@...omium.org>
To:     Nickey Yang <nickey.yang@...k-chips.com>
Cc:     thierry.reding@...il.com, airlied@...ux.ie,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        seanpaul@...omium.org, briannorris@...omium.org, hl@...k-chips.com,
        zyw@...k-chips.com
Subject: Re: [PATCH 2/3] drm/panel: add Kingdisplay kd097d04 panel driver

On Mon, Sep 18, 2017 at 04:40:01PM +0800, Nickey Yang wrote:
> Support Kingdisplay kd097d04 9.7" 1536x2048 TFT LCD panel,
> it is a MIPI DSI panel.
> 
> Signed-off-by: Nickey Yang <nickey.yang@...k-chips.com>

Hi Nickey,
This patch doesn't apply cleanly to drm-misc-next and the encoding is set to 'y'
instead of 'UTF-8'.

> ---
>  drivers/gpu/drm/panel/Kconfig                      |  11 +
>  drivers/gpu/drm/panel/Makefile                     |   1 +
>  drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c | 485 +++++++++++++++++++++
>  3 files changed, 497 insertions(+)
>  create mode 100644 drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c
> 
> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> index d84a031..8b1f0bd 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -50,6 +50,17 @@ config DRM_PANEL_JDI_LT070ME05000
>  	  The panel has a 1200(RGB)×1920 (WUXGA) resolution and uses
>  	  24 bit per pixel.
>  
> +config DRM_PANEL_KINGDISPLAY_KD097D04
> +	tristate "Kingdisplay kd097d04 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 Kingdisplay kd097d04
> +	  TFT-LCD modules. The panel has a 1536x2048 resolution and uses
> +	  24 bit RGB per pixel. It provides a MIPI DSI interface to
> +	  the host and has a built-in LED backlight.
> +
>  config DRM_PANEL_SAMSUNG_LD9040
>  	tristate "Samsung LD9040 RGB/SPI panel"
>  	depends on OF && SPI
> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
> index 9f6610d..2548931 100644
> --- a/drivers/gpu/drm/panel/Makefile
> +++ b/drivers/gpu/drm/panel/Makefile
> @@ -2,6 +2,7 @@ obj-$(CONFIG_DRM_PANEL_LVDS) += panel-lvds.o
>  obj-$(CONFIG_DRM_PANEL_SIMPLE) += panel-simple.o
>  obj-$(CONFIG_DRM_PANEL_INNOLUX_P079ZCA) += panel-innolux-p079zca.o
>  obj-$(CONFIG_DRM_PANEL_JDI_LT070ME05000) += panel-jdi-lt070me05000.o
> +obj-$(CONFIG_DRM_PANEL_KINGDISPLAY_KD097D04) += panel-kingdisplay-kd097d04.o
>  obj-$(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
> diff --git a/drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c b/drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c
> new file mode 100644
> index 0000000..359cd34
> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-kingdisplay-kd097d04.c
> @@ -0,0 +1,485 @@
> +/*
> + * Copyright (c) 2017, Fuzhou Rockchip Electronics Co., Ltd
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + */
> +
> +#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>
> +
> +struct kingdisplay_panel {
> +	struct drm_panel base;
> +	struct mipi_dsi_device *link;
> +
> +	struct backlight_device *backlight;
> +	struct regulator *supply;
> +	struct gpio_desc *enable_gpio;
> +
> +	bool prepared;
> +	bool enabled;

I really wish we didn't need to keep track of prepared/enabled here. Is this
just to protect the regulator refcount from unbalanced unprepare/prepare or
enabled/disable calls?

The reason I don't like it is it pretty much guarantees we won't be able to
recover from error paths since prepared/enabled are only flipped at the end of
the various hooks.

> +};
> +
> +struct kingdisplay_pannel_cmd {

s/pannel/panel/

> +	char cmd;
> +	char data;
> +};
> +
> +static const struct kingdisplay_pannel_cmd init_code[] = {

It doesn't look like these are standard DCS operations? Are these documented
anywhere? It would be great if you could #define some of these registers/values
such that they're useful for people without access to the datasheet (like
myself).

> +	/* voltage setting */
> +	{ 0xB0, 0x00 },
> +	{ 0xB2, 0x02 },
> +	{ 0xB3, 0x11 },
> +	{ 0xB4, 0x00 },
> +	{ 0xB6, 0x80 },
> +	/* VCOM disable */
> +	{ 0xB8, 0x80 },
> +	{ 0xBA, 0x43 },
> +	/* VCOM setting */
> +	{ 0xBB, 0x53 },
> +	/* VSP setting */
> +	{ 0xBC, 0x0A },
> +	/* VSN setting */
> +	{ 0xBD, 0x4A },
> +	/* VGH setting */
> +	{ 0xBE, 0x2F },
> +	/* VGL setting */
> +	{ 0xBF, 0x1A },
> +	{ 0xF0, 0x39 },
> +	{ 0xF1, 0x21 },
> +	/* Gamma setting */
> +	{ 0xB0, 0x02 },
> +	{ 0xC0, 0x00 },
> +	{ 0xC1, 0x01 },
> +	{ 0xC2, 0x0B },
> +	{ 0xC3, 0x15 },
> +	{ 0xC4, 0x22 },
> +	{ 0xC5, 0x11 },
> +	{ 0xC6, 0x15 },
> +	{ 0xC7, 0x19 },
> +	{ 0xC8, 0x1A },
> +	{ 0xC9, 0x16 },
> +	{ 0xCA, 0x18 },
> +	{ 0xCB, 0x13 },
> +	{ 0xCC, 0x18 },
> +	{ 0xCD, 0x13 },
> +	{ 0xCE, 0x1C },
> +	{ 0xCF, 0x19 },
> +	{ 0xD0, 0x21 },
> +	{ 0xD1, 0x2C },
> +	{ 0xD2, 0x2F },
> +	{ 0xD3, 0x30 },
> +	{ 0xD4, 0x19 },
> +	{ 0xD5, 0x1F },
> +	{ 0xD6, 0x00 },
> +	{ 0xD7, 0x01 },
> +	{ 0xD8, 0x0B },
> +	{ 0xD9, 0x15 },
> +	{ 0xDA, 0x22 },
> +	{ 0xDB, 0x11 },
> +	{ 0xDC, 0x15 },
> +	{ 0xDD, 0x19 },
> +	{ 0xDE, 0x1A },
> +	{ 0xDF, 0x16 },
> +	{ 0xE0, 0x18 },
> +	{ 0xE1, 0x13 },
> +	{ 0xE2, 0x18 },
> +	{ 0xE3, 0x13 },
> +	{ 0xE4, 0x1C },
> +	{ 0xE5, 0x19 },
> +	{ 0xE6, 0x21 },
> +	{ 0xE7, 0x2C },
> +	{ 0xE8, 0x2F },
> +	{ 0xE9, 0x30 },
> +	{ 0xEA, 0x19 },
> +	{ 0xEB, 0x1F },
> +	/* GOA MUX setting */
> +	{ 0xB0, 0x01 },
> +	{ 0xC0, 0x10 },
> +	{ 0xC1, 0x0F },
> +	{ 0xC2, 0x0E },
> +	{ 0xC3, 0x0D },
> +	{ 0xC4, 0x0C },
> +	{ 0xC5, 0x0B },
> +	{ 0xC6, 0x0A },
> +	{ 0xC7, 0x09 },
> +	{ 0xC8, 0x08 },
> +	{ 0xC9, 0x07 },
> +	{ 0xCA, 0x06 },
> +	{ 0xCB, 0x05 },
> +	{ 0xCC, 0x00 },
> +	{ 0xCD, 0x01 },
> +	{ 0xCE, 0x02 },
> +	{ 0xCF, 0x03 },
> +	{ 0xD0, 0x04 },
> +	{ 0xD6, 0x10 },
> +	{ 0xD7, 0x0F },
> +	{ 0xD8, 0x0E },
> +	{ 0xD9, 0x0D },
> +	{ 0xDA, 0x0C },
> +	{ 0xDB, 0x0B },
> +	{ 0xDC, 0x0A },
> +	{ 0xDD, 0x09 },
> +	{ 0xDE, 0x08 },
> +	{ 0xDF, 0x07 },
> +	{ 0xE0, 0x06 },
> +	{ 0xE1, 0x05 },
> +	{ 0xE2, 0x00 },
> +	{ 0xE3, 0x01 },
> +	{ 0xE4, 0x02 },
> +	{ 0xE5, 0x03 },
> +	{ 0xE6, 0x04 },
> +	{ 0xE7, 0x00 },
> +	{ 0xEC, 0xC0 },
> +	/* GOA timing setting */
> +	{ 0xB0, 0x03 },
> +	{ 0xC0, 0x01 },
> +	{ 0xC2, 0x6F },
> +	{ 0xC3, 0x6F },
> +	{ 0xC5, 0x36 },
> +	{ 0xC8, 0x08 },
> +	{ 0xC9, 0x04 },
> +	{ 0xCA, 0x41 },
> +	{ 0xCC, 0x43 },
> +	{ 0xCF, 0x60 },
> +	{ 0xD2, 0x04 },
> +	{ 0xD3, 0x04 },
> +	{ 0xD4, 0x03 },
> +	{ 0xD5, 0x02 },
> +	{ 0xD6, 0x01 },
> +	{ 0xD7, 0x00 },
> +	{ 0xDB, 0x01 },
> +	{ 0xDE, 0x36 },
> +	{ 0xE6, 0x6F },
> +	{ 0xE7, 0x6F },
> +	/* GOE setting */
> +	{ 0xB0, 0x06 },
> +	{ 0xB8, 0xA5 },
> +	{ 0xC0, 0xA5 },
> +	{ 0xD5, 0x3F },
> +};
> +
> +static inline struct kingdisplay_panel *to_kingdisplay_panel(struct drm_panel *panel)

>80 chars


> +{
> +	return container_of(panel, struct kingdisplay_panel, base);
> +}
> +
> +static int kingdisplay_panel_disable(struct drm_panel *panel)
> +{
> +	struct kingdisplay_panel *kingdisplay = to_kingdisplay_panel(panel);
> +	int err;
> +
> +	if (!kingdisplay->enabled)
> +		return 0;
> +
> +	kingdisplay->backlight->props.power = FB_BLANK_POWERDOWN;
> +	backlight_update_status(kingdisplay->backlight);
> +
> +	err = mipi_dsi_dcs_set_display_off(kingdisplay->link);
> +	if (err < 0)
> +		DRM_DEV_ERROR(panel->dev, "failed to set display off: %d\n",
> +			      err);
> +
> +	kingdisplay->enabled = false;
> +
> +	return 0;
> +}
> +
> +static int kingdisplay_panel_unprepare(struct drm_panel *panel)
> +{
> +	struct kingdisplay_panel *kingdisplay = to_kingdisplay_panel(panel);
> +	int err;
> +
> +	if (!kingdisplay->prepared)
> +		return 0;
> +
> +	err = mipi_dsi_dcs_enter_sleep_mode(kingdisplay->link);
> +	if (err < 0) {
> +		DRM_DEV_ERROR(panel->dev, "failed to enter sleep mode: %d\n",
> +			      err);
> +		return err;
> +	}
> +
> +	gpiod_set_value_cansleep(kingdisplay->enable_gpio, 0);
> +
> +	/* T8: 80ms - 1000ms */
> +	msleep(80);
> +
> +	err = regulator_disable(kingdisplay->supply);
> +	if (err < 0)

Log an error here. 

> +		return err;
> +
> +	kingdisplay->prepared = false;
> +
> +	return 0;
> +}
> +
> +static int kingdisplay_panel_prepare(struct drm_panel *panel)
> +{
> +	struct kingdisplay_panel *kingdisplay = to_kingdisplay_panel(panel);
> +	int err, regulator_err;
> +	int i;
> +
> +	if (kingdisplay->prepared)
> +		return 0;
> +
> +	gpiod_set_value_cansleep(kingdisplay->enable_gpio, 0);
> +
> +	err = regulator_enable(kingdisplay->supply);
> +	if (err < 0)
> +		return err;
> +
> +	/* T2: 15ms - 1000ms */
> +	usleep_range(15000, 16000);
> +
> +	gpiod_set_value_cansleep(kingdisplay->enable_gpio, 1);
> +
> +	/* T4: 15ms - 1000ms */
> +	usleep_range(15000, 16000);
> +
> +	for (i = 0; i < ARRAY_SIZE(init_code); i++)
> +		mipi_dsi_generic_write(kingdisplay->link, &init_code[i],
> +				       sizeof(struct kingdisplay_pannel_cmd));

Doing each command as a short write isn't exactly optimal. Any chance you can
compress multiple commands into a few long writes?

> +
> +	err = mipi_dsi_dcs_exit_sleep_mode(kingdisplay->link);
> +	if (err < 0) {
> +		DRM_DEV_ERROR(panel->dev, "failed to exit sleep mode: %d\n",
> +			      err);
> +		goto poweroff;
> +	}
> +
> +	/* T6: 120ms - 1000ms*/
> +	msleep(120);
> +
> +	err = mipi_dsi_dcs_set_display_on(kingdisplay->link);
> +	if (err < 0) {
> +		DRM_DEV_ERROR(panel->dev, "failed to set display on: %d\n",
> +			      err);
> +		goto poweroff;
> +	}
> +
> +	/* T7: 10ms */
> +	usleep_range(10000, 10000);
> +
> +	kingdisplay->prepared = true;
> +
> +	return 0;
> +
> +poweroff:
> +	regulator_err = regulator_disable(kingdisplay->supply);
> +	if (regulator_err)
> +		DRM_DEV_ERROR(panel->dev, "failed to disable regulator: %d\n",
> +			      regulator_err);
> +
> +	gpiod_set_value_cansleep(kingdisplay->enable_gpio, 0);
> +	return err;
> +}
> +
> +static int kingdisplay_panel_enable(struct drm_panel *panel)
> +{
> +	struct kingdisplay_panel *kingdisplay = to_kingdisplay_panel(panel);
> +	int ret;
> +
> +	if (kingdisplay->enabled)
> +		return 0;
> +
> +	kingdisplay->backlight->props.power = FB_BLANK_UNBLANK;
> +	ret = backlight_update_status(kingdisplay->backlight);
> +	if (ret) {
> +		DRM_DEV_ERROR(panel->drm->dev,
> +			      "Failed to enable backlight %d\n", ret);
> +		return ret;
> +	}
> +
> +	kingdisplay->enabled = true;
> +
> +	return 0;
> +}
> +
> +static const struct drm_display_mode default_mode = {
> +	.clock = 213000,
> +	.hdisplay = 1536,
> +	.hsync_start = 1536 + 70,
> +	.hsync_end = 1536 + 70 + 24,
> +	.htotal = 1536 + 70 + 24 + 70,
> +	.vdisplay = 2048,
> +	.vsync_start = 2048 + 17,
> +	.vsync_end = 2048 + 17 + 2,
> +	.vtotal = 2048 + 17 + 2 + 23,
> +	.vrefresh = 60,
> +};
> +
> +static int kingdisplay_panel_get_modes(struct drm_panel *panel)
> +{
> +	struct drm_display_mode *mode;
> +
> +	mode = drm_mode_duplicate(panel->drm, &default_mode);
> +	if (!mode) {
> +		DRM_DEV_ERROR(panel->drm->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 = 147;
> +	panel->connector->display_info.height_mm = 196;
> +	panel->connector->display_info.bpc = 8;
> +
> +	return 1;
> +}
> +
> +static const struct drm_panel_funcs kingdisplay_panel_funcs = {
> +	.disable = kingdisplay_panel_disable,
> +	.unprepare = kingdisplay_panel_unprepare,
> +	.prepare = kingdisplay_panel_prepare,
> +	.enable = kingdisplay_panel_enable,
> +	.get_modes = kingdisplay_panel_get_modes,
> +};
> +
> +static const struct of_device_id kingdisplay_of_match[] = {
> +	{ .compatible = "kingdisplay,kd097d04", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, kingdisplay_of_match);
> +
> +static int kingdisplay_panel_add(struct kingdisplay_panel *kingdisplay)
> +{
> +	struct device *dev = &kingdisplay->link->dev;
> +	struct device_node *np;
> +	int err;
> +
> +	kingdisplay->supply = devm_regulator_get(dev, "power");
> +	if (IS_ERR(kingdisplay->supply))
> +		return PTR_ERR(kingdisplay->supply);
> +
> +	kingdisplay->enable_gpio = devm_gpiod_get_optional(dev, "enable",
> +							   GPIOD_OUT_HIGH);
> +	if (IS_ERR(kingdisplay->enable_gpio)) {
> +		err = PTR_ERR(kingdisplay->enable_gpio);
> +		dev_dbg(dev, "failed to get enable gpio: %d\n", err);
> +		kingdisplay->enable_gpio = NULL;
> +	}
> +
> +	np = of_parse_phandle(dev->of_node, "backlight", 0);
> +	if (np) {
> +		kingdisplay->backlight = of_find_backlight_by_node(np);
> +		of_node_put(np);
> +
> +		if (!kingdisplay->backlight)
> +			return -EPROBE_DEFER;
> +	}
> +
> +	drm_panel_init(&kingdisplay->base);
> +	kingdisplay->base.funcs = &kingdisplay_panel_funcs;
> +	kingdisplay->base.dev = &kingdisplay->link->dev;
> +
> +	err = drm_panel_add(&kingdisplay->base);
> +	if (err < 0)
> +		goto put_backlight;
> +
> +	return 0;
> +
> +put_backlight:
> +	put_device(&kingdisplay->backlight->dev);
> +
> +	return err;
> +}
> +
> +static void kingdisplay_panel_del(struct kingdisplay_panel *kingdisplay)
> +{
> +	if (kingdisplay->base.dev)
> +		drm_panel_remove(&kingdisplay->base);
> +
> +	put_device(&kingdisplay->backlight->dev);
> +}
> +
> +static int kingdisplay_panel_probe(struct mipi_dsi_device *dsi)
> +{
> +	struct kingdisplay_panel *kingdisplay;
> +	int err;
> +
> +	dsi->lanes = 8;
> +	dsi->format = MIPI_DSI_FMT_RGB888;
> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST |
> +			  MIPI_DSI_MODE_LPM;
> +
> +	kingdisplay = devm_kzalloc(&dsi->dev, sizeof(*kingdisplay), GFP_KERNEL);
> +	if (!kingdisplay)
> +		return -ENOMEM;
> +
> +	mipi_dsi_set_drvdata(dsi, kingdisplay);
> +
> +	kingdisplay->link = dsi;
> +
> +	err = kingdisplay_panel_add(kingdisplay);
> +	if (err < 0)
> +		return err;
> +
> +	err = mipi_dsi_attach(dsi);
> +	return err;

Let's log some errors for failures in this function

> +}
> +
> +static int kingdisplay_panel_remove(struct mipi_dsi_device *dsi)
> +{
> +	struct kingdisplay_panel *kingdisplay = mipi_dsi_get_drvdata(dsi);
> +	int err;
> +
> +	err = kingdisplay_panel_unprepare(&kingdisplay->base);
> +	if (err < 0)
> +		DRM_DEV_ERROR(&dsi->dev, "failed to unprepare panel: %d\n",
> +			      err);
> +
> +	err = kingdisplay_panel_disable(&kingdisplay->base);
> +	if (err < 0)
> +		DRM_DEV_ERROR(&dsi->dev, "failed to disable panel: %d\n", err);
> +
> +	err = mipi_dsi_detach(dsi);
> +	if (err < 0)
> +		DRM_DEV_ERROR(&dsi->dev, "failed to detach from DSI host: %d\n",
> +			      err);
> +
> +	drm_panel_detach(&kingdisplay->base);
> +	kingdisplay_panel_del(kingdisplay);
> +
> +	return 0;
> +}
> +
> +static void kingdisplay_panel_shutdown(struct mipi_dsi_device *dsi)
> +{
> +	struct kingdisplay_panel *kingdisplay = mipi_dsi_get_drvdata(dsi);
> +
> +	kingdisplay_panel_unprepare(&kingdisplay->base);
> +	kingdisplay_panel_disable(&kingdisplay->base);
> +}
> +
> +static struct mipi_dsi_driver kingdisplay_panel_driver = {
> +	.driver = {
> +		.name = "panel-kingdisplay-kd097d04",
> +		.of_match_table = kingdisplay_of_match,
> +	},
> +	.probe = kingdisplay_panel_probe,
> +	.remove = kingdisplay_panel_remove,
> +	.shutdown = kingdisplay_panel_shutdown,
> +};
> +module_mipi_dsi_driver(kingdisplay_panel_driver);
> +
> +MODULE_AUTHOR("Chris Zhong <zyw@...k-chips.com>");
> +MODULE_AUTHOR("Nickey Yang <nickey.yang@...k-chips.com>");
> +MODULE_DESCRIPTION("kingdisplay KD097D04 panel driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 1.9.1
> 
> 

-- 
Sean Paul, Software Engineer, Google / Chromium OS

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