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Date:   Wed, 02 Mar 2022 10:38:26 +0000
From:   Paul Cercueil <paul@crapouillou.net>
Subject: Re: [PATCH v1 2/3] drm/panel: Add panel driver for NewVision NV3052C
 based LCDs
To:     Christophe Branchereau <cbranchereau@gmail.com>
Cc:     David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
        Thierry Reding <thierry.reding@gmail.com>,
        Sam Ravnborg <sam@ravnborg.org>, linux-kernel@vger.kernel.org,
        linux-mips@vger.kernel.org, dri-devel@lists.freedesktop.org
Message-Id: <2K548R.OKM2OPSDBF3L3@crapouillou.net>
In-Reply-To: <20220301153122.20660-3-cbranchereau@gmail.com>
References: <20220301153122.20660-1-cbranchereau@gmail.com>
        <20220301153122.20660-3-cbranchereau@gmail.com>
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Hi Christophe,

Le mar., mars 1 2022 at 16:31:21 +0100, Christophe Branchereau 
<cbranchereau@gmail.com> a ?crit :
> This driver supports the NewVision NV3052C based LCDs. Right now, it
> only supports the LeadTek LTK035C5444T 2.4" 640x480 TFT LCD panel, 
> which
> can be found in the Anbernic RG-350M handheld console.

You'd need to add a binding documentation for the NV3052C (in a 
separate patch).

> 
> Signed-off-by: Christophe Branchereau <cbranchereau@gmail.com>
> ---
>  drivers/gpu/drm/panel/Kconfig                 |   9 +
>  drivers/gpu/drm/panel/Makefile                |   1 +
>  .../gpu/drm/panel/panel-newvision-nv3052c.c   | 504 
> ++++++++++++++++++
>  3 files changed, 514 insertions(+)
>  create mode 100644 drivers/gpu/drm/panel/panel-newvision-nv3052c.c
> 
> diff --git a/drivers/gpu/drm/panel/Kconfig 
> b/drivers/gpu/drm/panel/Kconfig
> index bb2e47229c68..40084f709789 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -283,6 +283,15 @@ config DRM_PANEL_NEC_NL8048HL11
>  	  panel (found on the Zoom2/3/3630 SDP boards). To compile this 
> driver
>  	  as a module, choose M here.
> 
> +config DRM_PANEL_NEWVISION_NV3052C
> +	tristate "NewVision NV3052C RGB/SPI panel"
> +	depends on OF && SPI
> +	depends on BACKLIGHT_CLASS_DEVICE
> +	select DRM_MIPI_DBI
> +	help
> +	  Say Y here if you want to enable support for the panels built
> +	  around the NewVision NV3052C display controller.
> +
>  config DRM_PANEL_NOVATEK_NT35510
>  	tristate "Novatek NT35510 RGB panel driver"
>  	depends on OF
> diff --git a/drivers/gpu/drm/panel/Makefile 
> b/drivers/gpu/drm/panel/Makefile
> index 5740911f637c..42a7ab54234b 100644
> --- a/drivers/gpu/drm/panel/Makefile
> +++ b/drivers/gpu/drm/panel/Makefile
> @@ -26,6 +26,7 @@ obj-$(CONFIG_DRM_PANEL_LEADTEK_LTK500HD1829) += 
> panel-leadtek-ltk500hd1829.o
>  obj-$(CONFIG_DRM_PANEL_LG_LB035Q02) += panel-lg-lb035q02.o
>  obj-$(CONFIG_DRM_PANEL_LG_LG4573) += panel-lg-lg4573.o
>  obj-$(CONFIG_DRM_PANEL_NEC_NL8048HL11) += panel-nec-nl8048hl11.o
> +obj-$(CONFIG_DRM_PANEL_NEWVISION_NV3052C) += 
> panel-newvision-nv3052c.o
>  obj-$(CONFIG_DRM_PANEL_NOVATEK_NT35510) += panel-novatek-nt35510.o
>  obj-$(CONFIG_DRM_PANEL_NOVATEK_NT35560) += panel-novatek-nt35560.o
>  obj-$(CONFIG_DRM_PANEL_NOVATEK_NT35950) += panel-novatek-nt35950.o
> diff --git a/drivers/gpu/drm/panel/panel-newvision-nv3052c.c 
> b/drivers/gpu/drm/panel/panel-newvision-nv3052c.c
> new file mode 100644
> index 000000000000..08a3b33bcce0
> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-newvision-nv3052c.c
> @@ -0,0 +1,504 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * NevVision NV3052C IPS LCD panel driver
> + *
> + * Copyright (C) 2020, Paul Cercueil <paul@crapouillou.net>
> + * Copyright (C) 2022, Christophe Branchereau 
> <cbranchereau@gmail.com>
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/media-bus-format.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/spi/spi.h>
> +
> +#include <video/mipi_display.h>
> +
> +#include <drm/drm_mipi_dbi.h>
> +#include <drm/drm_modes.h>
> +#include <drm/drm_panel.h>
> +
> +struct nv3052c_panel_info {
> +	const struct drm_display_mode *display_modes;
> +	unsigned int num_modes;
> +	u16 width_mm, height_mm;
> +	u32 bus_format, bus_flags;
> +};
> +
> +struct nv3052c {
> +	struct device *dev;
> +	struct drm_panel panel;
> +	struct mipi_dbi dbi;
> +
> +	const struct nv3052c_panel_info *panel_info;
> +
> +	struct regulator *supply;
> +	struct gpio_desc *reset_gpio;
> +};
> +
> +struct nv3052c_reg {
> +	u8 cmd;
> +	u8 val;
> +};
> +
> +static const struct nv3052c_reg nv3052c_panel_regs[] = {
> +	{ 0xff, 0x30 },
> +	{ 0xff, 0x52 },
> +	{ 0xff, 0x01 },
> +	{ 0xe3, 0x00 },
> +	{ 0x40, 0x00 },
> +	{ 0x03, 0x40 },
> +	{ 0x04, 0x00 },
> +	{ 0x05, 0x03 },
> +	{ 0x08, 0x00 },
> +	{ 0x09, 0x07 },
> +	{ 0x0a, 0x01 },
> +	{ 0x0b, 0x32 },
> +	{ 0x0c, 0x32 },
> +	{ 0x0d, 0x0b },
> +	{ 0x0e, 0x00 },
> +	{ 0x23, 0xa0 },
> +
> +	{ 0x24, 0x0c },
> +	{ 0x25, 0x06 },
> +	{ 0x26, 0x14 },
> +	{ 0x27, 0x14 },
> +
> +	{ 0x38, 0xcc },
> +	{ 0x39, 0xd7 },
> +	{ 0x3a, 0x4a },
> +
> +	{ 0x28, 0x40 },
> +	{ 0x29, 0x01 },
> +	{ 0x2a, 0xdf },
> +	{ 0x49, 0x3c },
> +	{ 0x91, 0x77 },
> +	{ 0x92, 0x77 },
> +	{ 0xa0, 0x55 },
> +	{ 0xa1, 0x50 },
> +	{ 0xa4, 0x9c },
> +	{ 0xa7, 0x02 },
> +	{ 0xa8, 0x01 },
> +	{ 0xa9, 0x01 },
> +	{ 0xaa, 0xfc },
> +	{ 0xab, 0x28 },
> +	{ 0xac, 0x06 },
> +	{ 0xad, 0x06 },
> +	{ 0xae, 0x06 },
> +	{ 0xaf, 0x03 },
> +	{ 0xb0, 0x08 },
> +	{ 0xb1, 0x26 },
> +	{ 0xb2, 0x28 },
> +	{ 0xb3, 0x28 },
> +	{ 0xb4, 0x33 },
> +	{ 0xb5, 0x08 },
> +	{ 0xb6, 0x26 },
> +	{ 0xb7, 0x08 },
> +	{ 0xb8, 0x26 },
> +	{ 0xf0, 0x00 },
> +	{ 0xf6, 0xc0 },
> +
> +	{ 0xff, 0x30 },
> +	{ 0xff, 0x52 },
> +	{ 0xff, 0x02 },
> +	{ 0xb0, 0x0b },
> +	{ 0xb1, 0x16 },
> +	{ 0xb2, 0x17 },
> +	{ 0xb3, 0x2c },
> +	{ 0xb4, 0x32 },
> +	{ 0xb5, 0x3b },
> +	{ 0xb6, 0x29 },
> +	{ 0xb7, 0x40 },
> +	{ 0xb8, 0x0d },
> +	{ 0xb9, 0x05 },
> +	{ 0xba, 0x12 },
> +	{ 0xbb, 0x10 },
> +	{ 0xbc, 0x12 },
> +	{ 0xbd, 0x15 },
> +	{ 0xbe, 0x19 },
> +	{ 0xbf, 0x0e },
> +	{ 0xc0, 0x16 },
> +	{ 0xc1, 0x0a },
> +	{ 0xd0, 0x0c },
> +	{ 0xd1, 0x17 },
> +	{ 0xd2, 0x14 },
> +	{ 0xd3, 0x2e },
> +	{ 0xd4, 0x32 },
> +	{ 0xd5, 0x3c },
> +	{ 0xd6, 0x22 },
> +	{ 0xd7, 0x3d },
> +	{ 0xd8, 0x0d },
> +	{ 0xd9, 0x07 },
> +	{ 0xda, 0x13 },
> +	{ 0xdb, 0x13 },
> +	{ 0xdc, 0x11 },
> +	{ 0xdd, 0x15 },
> +	{ 0xde, 0x19 },
> +	{ 0xdf, 0x10 },
> +	{ 0xe0, 0x17 },
> +	{ 0xe1, 0x0a },
> +
> +	{ 0xff, 0x30 },
> +	{ 0xff, 0x52 },
> +	{ 0xff, 0x03 },
> +	{ 0x00, 0x2a },
> +	{ 0x01, 0x2a },
> +	{ 0x02, 0x2a },
> +	{ 0x03, 0x2a },
> +	{ 0x04, 0x61 },
> +	{ 0x05, 0x80 },
> +	{ 0x06, 0xc7 },
> +	{ 0x07, 0x01 },
> +	{ 0x08, 0x03 },
> +	{ 0x09, 0x04 },
> +	{ 0x70, 0x22 },
> +	{ 0x71, 0x80 },
> +	{ 0x30, 0x2a },
> +	{ 0x31, 0x2a },
> +	{ 0x32, 0x2a },
> +	{ 0x33, 0x2a },
> +	{ 0x34, 0x61 },
> +	{ 0x35, 0xc5 },
> +	{ 0x36, 0x80 },
> +	{ 0x37, 0x23 },
> +	{ 0x40, 0x03 },
> +	{ 0x41, 0x04 },
> +	{ 0x42, 0x05 },
> +	{ 0x43, 0x06 },
> +	{ 0x44, 0x11 },
> +	{ 0x45, 0xe8 },
> +	{ 0x46, 0xe9 },
> +	{ 0x47, 0x11 },
> +	{ 0x48, 0xea },
> +	{ 0x49, 0xeb },
> +	{ 0x50, 0x07 },
> +	{ 0x51, 0x08 },
> +	{ 0x52, 0x09 },
> +	{ 0x53, 0x0a },
> +	{ 0x54, 0x11 },
> +	{ 0x55, 0xec },
> +	{ 0x56, 0xed },
> +	{ 0x57, 0x11 },
> +	{ 0x58, 0xef },
> +	{ 0x59, 0xf0 },
> +	{ 0xb1, 0x01 },
> +	{ 0xb4, 0x15 },
> +	{ 0xb5, 0x16 },
> +	{ 0xb6, 0x09 },
> +	{ 0xb7, 0x0f },
> +	{ 0xb8, 0x0d },
> +	{ 0xb9, 0x0b },
> +	{ 0xba, 0x00 },
> +	{ 0xc7, 0x02 },
> +	{ 0xca, 0x17 },
> +	{ 0xcb, 0x18 },
> +	{ 0xcc, 0x0a },
> +	{ 0xcd, 0x10 },
> +	{ 0xce, 0x0e },
> +	{ 0xcf, 0x0c },
> +	{ 0xd0, 0x00 },
> +	{ 0x81, 0x00 },
> +	{ 0x84, 0x15 },
> +	{ 0x85, 0x16 },
> +	{ 0x86, 0x10 },
> +	{ 0x87, 0x0a },
> +	{ 0x88, 0x0c },
> +	{ 0x89, 0x0e },
> +	{ 0x8a, 0x02 },
> +	{ 0x97, 0x00 },
> +	{ 0x9a, 0x17 },
> +	{ 0x9b, 0x18 },
> +	{ 0x9c, 0x0f },
> +	{ 0x9d, 0x09 },
> +	{ 0x9e, 0x0b },
> +	{ 0x9f, 0x0d },
> +	{ 0xa0, 0x01 },
> +
> +	{ 0xff, 0x30 },
> +	{ 0xff, 0x52 },
> +	{ 0xff, 0x02 },
> +	{ 0x01, 0x01 },
> +	{ 0x02, 0xda },
> +	{ 0x03, 0xba },
> +	{ 0x04, 0xa8 },
> +	{ 0x05, 0x9a },
> +	{ 0x06, 0x70 },
> +	{ 0x07, 0xff },
> +	{ 0x08, 0x91 },
> +	{ 0x09, 0x90 },
> +	{ 0x0a, 0xff },
> +	{ 0x0b, 0x8f },
> +	{ 0x0c, 0x60 },
> +	{ 0x0d, 0x58 },
> +	{ 0x0e, 0x48 },
> +	{ 0x0f, 0x38 },
> +	{ 0x10, 0x2b },
> +
> +	{ 0xff, 0x30 },
> +	{ 0xff, 0x52 },
> +	{ 0xff, 0x00 },
> +	{ 0x36, 0x0a },
> +};
> +
> +static inline struct nv3052c *to_nv3052c(struct drm_panel *panel)
> +{
> +	return container_of(panel, struct nv3052c, panel);
> +}
> +
> +static int nv3052c_prepare(struct drm_panel *panel)
> +{
> +	struct nv3052c *priv = to_nv3052c(panel);
> +	struct mipi_dbi *dbi = &priv->dbi;
> +	unsigned int i;
> +	int err;
> +
> +	err = regulator_enable(priv->supply);
> +	if (err) {
> +		dev_err(priv->dev, "Failed to enable power supply: %d\n", err);
> +		return err;
> +	}
> +
> +	/* Reset the chip */
> +	gpiod_set_value_cansleep(priv->reset_gpio, 1);
> +	usleep_range(10, 1000);
> +	gpiod_set_value_cansleep(priv->reset_gpio, 0);
> +	msleep(5);
> +
> +	for (i = 0; i < ARRAY_SIZE(nv3052c_panel_regs); i++) {
> +		err = mipi_dbi_command(dbi, nv3052c_panel_regs[i].cmd,
> +				       nv3052c_panel_regs[i].val);
> +
> +		if (err) {
> +			dev_err(priv->dev, "Unable to set register: %d\n", err);
> +			goto err_disable_regulator;
> +		}
> +	}
> +
> +	err = mipi_dbi_command(dbi, MIPI_DCS_EXIT_SLEEP_MODE);
> +	if (err) {
> +		dev_err(priv->dev, "Unable to exit sleep mode: %d\n", err);
> +		goto err_disable_regulator;
> +	}
> +
> +	return 0;
> +
> +err_disable_regulator:
> +	regulator_disable(priv->supply);
> +	return err;
> +}
> +
> +static int nv3052c_unprepare(struct drm_panel *panel)
> +{
> +	struct nv3052c *priv = to_nv3052c(panel);
> +	struct mipi_dbi *dbi = &priv->dbi;
> +	int err;
> +
> +	err = mipi_dbi_command(dbi, MIPI_DCS_ENTER_SLEEP_MODE);
> +	if (err) {
> +		dev_err(priv->dev, "Unable to enter sleep mode: %d\n", err);
> +		return err;
> +	}
> +
> +	gpiod_set_value_cansleep(priv->reset_gpio, 1);
> +	regulator_disable(priv->supply);
> +
> +	return 0;
> +}
> +
> +static int nv3052c_enable(struct drm_panel *panel)
> +{
> +	struct nv3052c *priv = to_nv3052c(panel);
> +	struct mipi_dbi *dbi = &priv->dbi;
> +	int err;
> +
> +	err = mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_ON);
> +	if (err) {
> +		dev_err(priv->dev, "Unable to enable display: %d\n", err);
> +		return err;
> +	}
> +
> +	if (panel->backlight) {
> +		/* Wait for the picture to be ready before enabling backlight */
> +		msleep(120);
> +	}
> +
> +	return 0;
> +}
> +
> +static int nv3052c_disable(struct drm_panel *panel)
> +{
> +	struct nv3052c *priv = to_nv3052c(panel);
> +	struct mipi_dbi *dbi = &priv->dbi;
> +	int err;
> +
> +	err = mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_OFF);
> +	if (err) {
> +		dev_err(priv->dev, "Unable to disable display: %d\n", err);
> +		return err;
> +	}
> +
> +	return 0;
> +}
> +
> +static int nv3052c_get_modes(struct drm_panel *panel,
> +			     struct drm_connector *connector)
> +{
> +	struct nv3052c *priv = to_nv3052c(panel);
> +	const struct nv3052c_panel_info *panel_info = priv->panel_info;
> +	struct drm_display_mode *mode;
> +	unsigned int i;
> +
> +	for (i = 0; i < panel_info->num_modes; i++) {
> +		mode = drm_mode_duplicate(connector->dev,
> +					  &panel_info->display_modes[i]);
> +		if (!mode)
> +			return -ENOMEM;
> +
> +		drm_mode_set_name(mode);
> +
> +		mode->type = DRM_MODE_TYPE_DRIVER;
> +		if (panel_info->num_modes == 1)
> +			mode->type |= DRM_MODE_TYPE_PREFERRED;
> +
> +		drm_mode_probed_add(connector, mode);
> +	}
> +
> +	connector->display_info.bpc = 8;
> +	connector->display_info.width_mm = panel_info->width_mm;
> +	connector->display_info.height_mm = panel_info->height_mm;
> +
> +	drm_display_info_set_bus_formats(&connector->display_info,
> +					 &panel_info->bus_format, 1);
> +	connector->display_info.bus_flags = panel_info->bus_flags;
> +
> +	return panel_info->num_modes;
> +}
> +
> +static const struct drm_panel_funcs nv3052c_funcs = {
> +	.prepare	= nv3052c_prepare,
> +	.unprepare	= nv3052c_unprepare,
> +	.enable		= nv3052c_enable,
> +	.disable	= nv3052c_disable,
> +	.get_modes	= nv3052c_get_modes,
> +};
> +
> +static int nv3052c_probe(struct spi_device *spi)
> +{
> +	struct device *dev = &spi->dev;
> +	struct nv3052c *priv;
> +	int err;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->dev = dev;
> +
> +	priv->panel_info = of_device_get_match_data(dev);
> +	if (!priv->panel_info)
> +		return -EINVAL;
> +
> +	priv->supply = devm_regulator_get(dev, "power");
> +	if (IS_ERR(priv->supply)) {
> +		dev_err(dev, "Failed to get power supply\n");
> +		return PTR_ERR(priv->supply);

You can use dev_err_probe() here,

> +	}
> +
> +	priv->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(priv->reset_gpio)) {
> +		dev_err(dev, "Failed to get reset GPIO\n");
> +		return PTR_ERR(priv->reset_gpio);

and here as well, since devm_{regulator,gpiod}_get() may return 
-EPROBE_DEFER.

The rest of the driver looks fine to me.

Cheers,
-Paul

> +	}
> +
> +	err = mipi_dbi_spi_init(spi, &priv->dbi, NULL);
> +	if (err)
> +		return dev_err_probe(dev, err, "MIPI DBI init failed\n");
> +
> +	priv->dbi.read_commands = NULL;
> +
> +	spi_set_drvdata(spi, priv);
> +
> +	drm_panel_init(&priv->panel, dev, &nv3052c_funcs,
> +		       DRM_MODE_CONNECTOR_DPI);
> +
> +	err = drm_panel_of_backlight(&priv->panel);
> +	if (err < 0) {
> +		if (err != -EPROBE_DEFER)
> +			dev_err(dev, "Failed to attach backlight\n");
> +		return err;
> +	}
> +
> +	drm_panel_add(&priv->panel);
> +
> +	return 0;
> +}
> +
> +static int nv3052c_remove(struct spi_device *spi)
> +{
> +	struct nv3052c *priv = spi_get_drvdata(spi);
> +
> +	drm_panel_remove(&priv->panel);
> +	drm_panel_disable(&priv->panel);
> +	drm_panel_unprepare(&priv->panel);
> +
> +	return 0;
> +}
> +
> +static const struct drm_display_mode ltk035c5444t_modes[] = {
> +	{ /* 60 Hz */
> +		.clock = 24000,
> +		.hdisplay = 640,
> +		.hsync_start = 640 + 96,
> +		.hsync_end = 640 + 96 + 16,
> +		.htotal = 640 + 96 + 16 + 48,
> +		.vdisplay = 480,
> +		.vsync_start = 480 + 5,
> +		.vsync_end = 480 + 5 + 2,
> +		.vtotal = 480 + 5 + 2 + 13,
> +		.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
> +	},
> +	{ /* 50 Hz */
> +		.clock = 18000,
> +		.hdisplay = 640,
> +		.hsync_start = 640 + 39,
> +		.hsync_end = 640 + 39 + 2,
> +		.htotal = 640 + 39 + 2 + 39,
> +		.vdisplay = 480,
> +		.vsync_start = 480 + 5,
> +		.vsync_end = 480 + 5 + 2,
> +		.vtotal = 480 + 5 + 2 + 13,
> +		.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
> +	},
> +};
> +
> +static const struct nv3052c_panel_info ltk035c5444t_spi_panel_info = 
> {
> +	.display_modes = ltk035c5444t_modes,
> +	.num_modes = ARRAY_SIZE(ltk035c5444t_modes),
> +	.width_mm = 77,
> +	.height_mm = 64,
> +	.bus_format = MEDIA_BUS_FMT_RGB888_1X24,
> +	.bus_flags = DRM_BUS_FLAG_DE_HIGH | 
> DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE,
> +};
> +
> +static const struct of_device_id nv3052c_of_match[] = {
> +	{ .compatible = "leadtek,ltk035c5444t-spi", .data = 
> &ltk035c5444t_spi_panel_info },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, nv3052c_of_match);
> +
> +static struct spi_driver nv3052c_driver = {
> +	.driver = {
> +		.name = "nv3052c",
> +		.of_match_table = nv3052c_of_match,
> +	},
> +	.probe = nv3052c_probe,
> +	.remove = nv3052c_remove,
> +};
> +module_spi_driver(nv3052c_driver);
> +
> +MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
> +MODULE_AUTHOR("Christophe Branchereau <cbranchereau@gmail.com>");
> +MODULE_LICENSE("GPL v2");
> --
> 2.34.1
>