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Date: Tue, 14 Mar 2017 13:01:35 -0400
From: Sean Paul <seanpaul@chromium.org>
To: Chris Zhong <zyw@rock-chips.com>
Cc: linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 2/2] drm/panel: add innolux,p079zca panel driver
Message-ID: <20170314170135.GB20329@art_vandelay>
References: <1488502909-22160-1-git-send-email-zyw@rock-chips.com>
 <1488502909-22160-2-git-send-email-zyw@rock-chips.com>
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On Fri, Mar 03, 2017 at 09:01:49AM +0800, Chris Zhong wrote:
> Support Innolux P079ZCA 7.85" 768x1024 TFT LCD panel, it is a MIPI DSI
> panel.
> 
> Signed-off-by: Chris Zhong <zyw@rock-chips.com>
> ---
> 
>  drivers/gpu/drm/panel/Kconfig                 |  11 +
>  drivers/gpu/drm/panel/Makefile                |   1 +
>  drivers/gpu/drm/panel/panel-innolux-p079zca.c | 322 ++++++++++++++++++++++++++
>  3 files changed, 334 insertions(+)
>  create mode 100644 drivers/gpu/drm/panel/panel-innolux-p079zca.c
> 
> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> index 62aba97..99dd010 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -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_INNOLUX_P079ZCA
> +	tristate "Innolux P079ZCA 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 Innolux P079ZCA
> +	  TFT-LCD modules. The panel has a 1024x768 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_JDI_LT070ME05000
>  	tristate "JDI LT070ME05000 WUXGA DSI panel"
>  	depends on OF
> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
> index a5c7ec0..bda2aa4 100644
> --- a/drivers/gpu/drm/panel/Makefile
> +++ b/drivers/gpu/drm/panel/Makefile
> @@ -1,4 +1,5 @@
>  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_LG_LG4573) += panel-lg-lg4573.o
>  obj-$(CONFIG_DRM_PANEL_PANASONIC_VVX10F034N00) += panel-panasonic-vvx10f034n00.o
> diff --git a/drivers/gpu/drm/panel/panel-innolux-p079zca.c b/drivers/gpu/drm/panel/panel-innolux-p079zca.c
> new file mode 100644
> index 0000000..5d16705
> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-innolux-p079zca.c
> @@ -0,0 +1,322 @@
> +/*
> + * 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 innolux_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;
> +};
> +
> +static inline struct innolux_panel *to_innolux_panel(struct drm_panel *panel)
> +{
> +	return container_of(panel, struct innolux_panel, base);
> +}
> +
> +static int innolux_panel_disable(struct drm_panel *panel)
> +{
> +	struct innolux_panel *innolux = to_innolux_panel(panel);
> +	int err;
> +
> +	if (!innolux->enabled)
> +		return 0;
> +
> +	if (innolux->backlight) {
> +		innolux->backlight->props.power = FB_BLANK_POWERDOWN;
> +		backlight_update_status(innolux->backlight);
> +	}
> +
> +	innolux->link->mode_flags &= ~MIPI_DSI_MODE_LPM;

Can you comment on why you need to remove this flag here (and re-enable it
everywhere else)?

> +
> +	err = mipi_dsi_dcs_set_display_off(innolux->link);
> +	if (err < 0)
> +		dev_err(panel->dev, "failed to set display off: %d\n", err);

DRM_DEV_ERROR is now a thing. Let's use that (here and elsewhere).

> +
> +	innolux->enabled = false;
> +
> +	return 0;
> +}
> +
> +static int innolux_panel_unprepare(struct drm_panel *panel)
> +{
> +	struct innolux_panel *innolux = to_innolux_panel(panel);
> +	int err;
> +
> +	if (!innolux->prepared)
> +		return 0;
> +
> +	innolux->link->mode_flags |= MIPI_DSI_MODE_LPM;
> +
> +	err = mipi_dsi_dcs_enter_sleep_mode(innolux->link);
> +	if (err < 0)
> +		dev_err(panel->dev, "failed to enter sleep mode: %d\n", err);
> +
> +	gpiod_set_value_cansleep(innolux->enable_gpio, 0);
> +	msleep(120);

There are a lot of sleeps sprinkled around the driver, and none of them are
documented. Can you please provide comments for the delays pointing the reader
to the corresponding value in the datasheet? (ie: /* T5- 100-130ms */)

> +
> +	regulator_disable(innolux->supply);

Check the return value?

> +
> +	innolux->prepared = false;
> +
> +	return 0;
> +}
> +
> +static int innolux_panel_prepare(struct drm_panel *panel)
> +{
> +	struct innolux_panel *innolux = to_innolux_panel(panel);
> +	int err;
> +
> +	if (innolux->prepared)
> +		return 0;
> +
> +	gpiod_set_value_cansleep(innolux->enable_gpio, 0);
> +
> +	err = regulator_enable(innolux->supply);
> +	if (err < 0)
> +		return err;
> +
> +	usleep_range(16000, 17000);
> +	gpiod_set_value_cansleep(innolux->enable_gpio, 1);
> +	usleep_range(15000, 16000);
> +
> +	innolux->link->mode_flags |= MIPI_DSI_MODE_LPM;
> +
> +	err = mipi_dsi_dcs_exit_sleep_mode(innolux->link);
> +	if (err < 0) {
> +		dev_err(panel->dev, "failed to exit sleep mode: %d\n", err);
> +		goto poweroff;
> +	}
> +
> +	msleep(120);
> +
> +	err = mipi_dsi_dcs_set_display_on(innolux->link);
> +	if (err < 0) {
> +		dev_err(panel->dev, "failed to set display on: %d\n", err);
> +		goto poweroff;
> +	}
> +
> +	usleep_range(5000, 6000);
> +
> +	innolux->prepared = true;
> +
> +	return 0;
> +
> +poweroff:
> +	regulator_disable(innolux->supply);

Check return value here.

Should you also reset the gpio value?

> +	return err;
> +}
> +
> +static int innolux_panel_enable(struct drm_panel *panel)
> +{
> +	struct innolux_panel *innolux = to_innolux_panel(panel);
> +
> +	if (innolux->enabled)
> +		return 0;
> +
> +	if (innolux->backlight) {
> +		innolux->backlight->props.power = FB_BLANK_UNBLANK;
> +		backlight_update_status(innolux->backlight);

Check return value

> +	}
> +
> +	innolux->enabled = true;
> +
> +	return 0;
> +}
> +
> +static const struct drm_display_mode default_mode = {
> +	.clock = 56900,
> +	.hdisplay = 768,
> +	.hsync_start = 768 + 40,
> +	.hsync_end = 768 + 40 + 40,
> +	.htotal = 768 + 40 + 40 + 40,
> +	.vdisplay = 1024,
> +	.vsync_start = 1024 + 20,
> +	.vsync_end = 1024 + 20 + 4,
> +	.vtotal = 1024 + 20 + 4 + 20,
> +	.vrefresh = 60,
> +};
> +
> +static int innolux_panel_get_modes(struct drm_panel *panel)
> +{
> +	struct drm_display_mode *mode;
> +
> +	mode = drm_mode_duplicate(panel->drm, &default_mode);
> +	if (!mode) {
> +		dev_err(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 = 120;
> +	panel->connector->display_info.height_mm = 160;
> +
> +	return 1;
> +}
> +
> +static const struct drm_panel_funcs innolux_panel_funcs = {
> +	.disable = innolux_panel_disable,
> +	.unprepare = innolux_panel_unprepare,
> +	.prepare = innolux_panel_prepare,
> +	.enable = innolux_panel_enable,
> +	.get_modes = innolux_panel_get_modes,
> +};
> +
> +static const struct of_device_id innolux_of_match[] = {
> +	{ .compatible = "innolux,p079zca", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, innolux_of_match);
> +
> +static int innolux_panel_add(struct innolux_panel *innolux)
> +{
> +	struct device *dev = &innolux->link->dev;
> +	struct device_node *np;
> +	int err;
> +
> +	innolux->supply = devm_regulator_get(dev, "power");
> +	if (IS_ERR(innolux->supply))
> +		return PTR_ERR(innolux->supply);
> +
> +	innolux->enable_gpio = devm_gpiod_get_optional(dev, "enable",
> +						       GPIOD_OUT_HIGH);
> +	if (IS_ERR(innolux->enable_gpio)) {
> +		err = PTR_ERR(innolux->enable_gpio);
> +		dev_dbg(dev, "failed to get enable gpio: %d\n", err);
> +		innolux->enable_gpio = NULL;
> +	}
> +
> +	np = of_parse_phandle(dev->of_node, "backlight", 0);
> +	if (np) {
> +		innolux->backlight = of_find_backlight_by_node(np);
> +		of_node_put(np);
> +
> +		if (!innolux->backlight)
> +			return -EPROBE_DEFER;
> +	}
> +
> +	drm_panel_init(&innolux->base);
> +	innolux->base.funcs = &innolux_panel_funcs;
> +	innolux->base.dev = &innolux->link->dev;
> +
> +	err = drm_panel_add(&innolux->base);
> +	if (err < 0)
> +		goto put_backlight;
> +
> +	return 0;
> +
> +put_backlight:
> +	if (innolux->backlight)
> +		put_device(&innolux->backlight->dev);
> +
> +	return err;
> +}
> +
> +static void innolux_panel_del(struct innolux_panel *innolux)
> +{
> +	if (innolux->base.dev)
> +		drm_panel_remove(&innolux->base);
> +
> +	if (innolux->backlight)
> +		put_device(&innolux->backlight->dev);
> +}
> +
> +static int innolux_panel_probe(struct mipi_dsi_device *dsi)
> +{
> +	struct innolux_panel *innolux;
> +	int err;
> +
> +	dsi->lanes = 4;
> +	dsi->format = MIPI_DSI_FMT_RGB888;
> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_SYNC_PULSE |
> +			  MIPI_DSI_MODE_LPM;
> +
> +	innolux = devm_kzalloc(&dsi->dev, sizeof(*innolux), GFP_KERNEL);
> +	if (!innolux)
> +		return -ENOMEM;
> +
> +	mipi_dsi_set_drvdata(dsi, innolux);
> +
> +	innolux->link = dsi;
> +
> +	err = innolux_panel_add(innolux);
> +	if (err < 0)
> +		return err;
> +
> +	err = mipi_dsi_attach(dsi);
> +	return err;
> +}
> +
> +static int innolux_panel_remove(struct mipi_dsi_device *dsi)
> +{
> +	struct innolux_panel *innolux = mipi_dsi_get_drvdata(dsi);
> +	int err;
> +
> +	err = innolux_panel_unprepare(&innolux->base);
> +	if (err < 0)
> +		dev_err(&dsi->dev, "failed to unprepare panel: %d\n", err);
> +
> +	err = innolux_panel_disable(&innolux->base);
> +	if (err < 0)
> +		dev_err(&dsi->dev, "failed to disable panel: %d\n", err);
> +
> +	err = mipi_dsi_detach(dsi);
> +	if (err < 0)
> +		dev_err(&dsi->dev, "failed to detach from DSI host: %d\n", err);
> +
> +	drm_panel_detach(&innolux->base);
> +	innolux_panel_del(innolux);
> +
> +	return 0;
> +}
> +
> +static void innolux_panel_shutdown(struct mipi_dsi_device *dsi)
> +{
> +	struct innolux_panel *innolux = mipi_dsi_get_drvdata(dsi);
> +
> +	innolux_panel_unprepare(&innolux->base);
> +	innolux_panel_disable(&innolux->base);
> +}
> +
> +static struct mipi_dsi_driver innolux_panel_driver = {
> +	.driver = {
> +		.name = "panel-innolux-p079zca",
> +		.of_match_table = innolux_of_match,
> +	},
> +	.probe = innolux_panel_probe,
> +	.remove = innolux_panel_remove,
> +	.shutdown = innolux_panel_shutdown,
> +};
> +module_mipi_dsi_driver(innolux_panel_driver);
> +
> +MODULE_AUTHOR("Chris Zhong <zyw@rock-chips.com>");
> +MODULE_DESCRIPTION("Innolux P079ZCA panel driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.6.3
> 
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