Re: [PATCH 21/60] drm/panel: Add driver for the Sharp LS037V7DW01 panel

From: Sam Ravnborg <sam@ravnborg.org>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Maxime Ripard <maxime.ripard@bootlin.com>,
	Sebastian Reichel <sebastian.reichel@collabora.com>,
	dri-devel@lists.freedesktop.org,
	Tomi Valkeinen <tomi.valkeinen@ti.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	Sean Paul <sean@poorly.run>
Subject: Re: [PATCH 21/60] drm/panel: Add driver for the Sharp LS037V7DW01 panel
Date: Mon, 8 Jul 2019 21:44:52 +0200	[thread overview]
Message-ID: <20190708194452.GA5192@ravnborg.org> (raw)
In-Reply-To: <20190707181937.6250-18-laurent.pinchart@ideasonboard.com>

Hi Laurent.

Third panel driver in line for review.
Review comments that are duplicates from the first two will have only a
brief remark - if any.

On Sun, Jul 07, 2019 at 09:18:58PM +0300, Laurent Pinchart wrote:
> This panel is used on the SDP3430.
Add a little more context and put it in Kconfig help.
Maybe this is the TI board, and maybe it is something else.

> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> ---
>  drivers/gpu/drm/panel/Kconfig                 |   7 +
>  drivers/gpu/drm/panel/Makefile                |   1 +
>  .../gpu/drm/panel/panel-sharp-ls037v7dw01.c   | 231 ++++++++++++++++++
>  3 files changed, 239 insertions(+)
>  create mode 100644 drivers/gpu/drm/panel/panel-sharp-ls037v7dw01.c
> 
> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> index da613c04b835..04fd152efe4c 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -271,6 +271,13 @@ config DRM_PANEL_SHARP_LS043T1LE01
>  	  Say Y here if you want to enable support for Sharp LS043T1LE01 qHD
>  	  (540x960) DSI panel as found on the Qualcomm APQ8074 Dragonboard
>  
> +config DRM_PANEL_SHARP_LS037V7DW01
> +	tristate "Sharp LS037V7DW01 VGA LCD panel"
> +	depends on GPIOLIB && OF && REGULATOR
> +	help
> +	  Say Y here if you want to enable support for Sharp LS037V7DW01 VGA
> +	  (480x640) LCD panel.
> +
Alphabetical order, so it comes before DRM_PANEL_SHARP_LS043T1LE01

>  config DRM_PANEL_SITRONIX_ST7701
>  	tristate "Sitronix ST7701 panel driver"
>  	depends on OF
> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
> index e81ed1535024..12dcd76eb87c 100644
> --- a/drivers/gpu/drm/panel/Makefile
> +++ b/drivers/gpu/drm/panel/Makefile
> @@ -27,6 +27,7 @@ obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E63M0) += panel-samsung-s6e63m0.o
>  obj-$(CONFIG_DRM_PANEL_SAMSUNG_S6E8AA0) += panel-samsung-s6e8aa0.o
>  obj-$(CONFIG_DRM_PANEL_SEIKO_43WVF1G) += panel-seiko-43wvf1g.o
>  obj-$(CONFIG_DRM_PANEL_SHARP_LQ101R1SX01) += panel-sharp-lq101r1sx01.o
> +obj-$(CONFIG_DRM_PANEL_SHARP_LS037V7DW01) += panel-sharp-ls037v7dw01.o
>  obj-$(CONFIG_DRM_PANEL_SHARP_LS043T1LE01) += panel-sharp-ls043t1le01.o
And here it is right.

> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-sharp-ls037v7dw01.c
> @@ -0,0 +1,231 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Sharp LS037V7DW01 LCD Panel Driver
> + *
> + * Copyright (C) 2019 Texas Instruments Incorporated
> + *
> + * Based on the omapdrm-specific panel-sharp-ls037v7dw01 driver
> + *
> + * Copyright (C) 2013 Texas Instruments Incorporated
> + * Author: Tomi Valkeinen <tomi.valkeinen@ti.com>
Add your copyright?

> +struct ls037v7dw01_device {
> +	struct drm_panel panel;
> +	struct platform_device *pdev;
> +
> +	struct regulator *vcc;
The property is named envdd - should they use the same name?

> +	struct gpio_desc *resb_gpio;	/* low = reset active min 20 us */
> +	struct gpio_desc *ini_gpio;	/* high = power on */
> +	struct gpio_desc *mo_gpio;	/* low = 480x640, high = 240x320 */
> +	struct gpio_desc *lr_gpio;	/* high = conventional horizontal scanning */
> +	struct gpio_desc *ud_gpio;	/* high = conventional vertical scanning */
> +};
device versus panel, but bikeshedding, so feel free to ignore.

> +
> +static int ls037v7dw01_disable(struct drm_panel *panel)
> +{
> +	struct ls037v7dw01_device *lcd = to_ls037v7dw01_device(panel);
> +
> +	gpiod_set_value_cansleep(lcd->ini_gpio, 0);
> +	gpiod_set_value_cansleep(lcd->resb_gpio, 0);
> +
> +	/* Wait at least 5 vsyncs after disabling the LCD. */
> +	msleep(100);
> +
> +	return 0;
> +}
> +
> +static int ls037v7dw01_unprepare(struct drm_panel *panel)
> +{
> +	struct ls037v7dw01_device *lcd = to_ls037v7dw01_device(panel);
> +
> +	if (lcd->vcc)
> +		regulator_disable(lcd->vcc);
Why is the if (lcd-vcc) needed?
If I read the probe code correct then we either get a regulator or we
error out.

Same goes for all other checks of lcd->vcc

> +static const struct drm_display_mode ls037v7dw01_mode = {
> +	.clock = 19200,
> +	.hdisplay = 480,
> +	.hsync_start = 480 + 1,
> +	.hsync_end = 480 + 1 + 2,
> +	.htotal = 480 + 1 + 2 + 28,
> +	.vdisplay = 640,
> +	.vsync_start = 640 + 1,
> +	.vsync_end = 640 + 1 + 1,
> +	.vtotal = 640 + 1 + 1 + 1,
> +	.vrefresh = 58,
> +	.type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED,
> +	.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
> +};
> +
> +static int ls037v7dw01_get_modes(struct drm_panel *panel)
> +{
> +	struct drm_connector *connector = panel->connector;
> +	struct drm_display_mode *mode;
> +
> +	mode = drm_mode_duplicate(panel->drm, &ls037v7dw01_mode);
> +	if (!mode)
> +		return -ENOMEM;
> +
> +	drm_mode_set_name(mode);
> +	drm_mode_probed_add(connector, mode);
> +
> +	connector->display_info.width_mm = 56;
> +	connector->display_info.height_mm = 75;
> +	/*
> +	 * FIXME: According to the datasheet pixel data is sampled on the
> +	 * rising edge of the clock, but the code running on the SDP3430
> +	 * indicates sampling on the negative edge. This should be tested on a
> +	 * real device.
> +	 */
> +	connector->display_info.bus_flags = DRM_BUS_FLAG_DE_HIGH
> +					  | DRM_BUS_FLAG_SYNC_SAMPLE_POSEDGE
> +					  | DRM_BUS_FLAG_PIXDATA_SAMPLE_NEGEDGE;
> +
> +	return 1;
> +}
> +
> +static const struct drm_panel_funcs ls037v7dw01_funcs = {
> +	.disable = ls037v7dw01_disable,
> +	.unprepare = ls037v7dw01_unprepare,
> +	.prepare = ls037v7dw01_prepare,
> +	.enable = ls037v7dw01_enable,
> +	.get_modes = ls037v7dw01_get_modes,
> +};
> +
> +static int ls037v7dw01_probe(struct platform_device *pdev)
> +{
> +	struct ls037v7dw01_device *lcd;
> +
> +	lcd = devm_kzalloc(&pdev->dev, sizeof(*lcd), GFP_KERNEL);
> +	if (lcd == NULL)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, lcd);
> +	lcd->pdev = pdev;
> +
> +	lcd->vcc = devm_regulator_get(&pdev->dev, "envdd");
> +	if (IS_ERR(lcd->vcc)) {
> +		dev_err(&pdev->dev, "failed to get regulator\n");
> +		return PTR_ERR(lcd->vcc);
> +	}
> +
> +	lcd->ini_gpio = devm_gpiod_get_index(&pdev->dev, "enable", 0,
> +					    GPIOD_OUT_LOW);
> +	if (IS_ERR(lcd->ini_gpio)) {
> +		dev_err(&pdev->dev, "failed to get enable gpio\n");
> +		return PTR_ERR(lcd->ini_gpio);
> +	}
I fail to see why the _index() variant is used here.
But then I did not check the binding, so it may originate from that.
Same goes for ireset gpio

> +
> +	lcd->resb_gpio = devm_gpiod_get_index(&pdev->dev, "reset", 0,
> +					     GPIOD_OUT_LOW);
> +	if (IS_ERR(lcd->resb_gpio)) {
> +		dev_err(&pdev->dev, "failed to get reset gpio\n");
> +		return PTR_ERR(lcd->resb_gpio);
> +	}
> +
> +	lcd->mo_gpio = devm_gpiod_get_index(&pdev->dev, "mode", 0,
> +					   GPIOD_OUT_LOW);
> +	if (IS_ERR(lcd->mo_gpio)) {
> +		dev_err(&pdev->dev, "failed to get mode[0] gpio\n");
> +		return PTR_ERR(lcd->mo_gpio);
> +	}
> +
> +	lcd->lr_gpio = devm_gpiod_get_index(&pdev->dev, "mode", 1,
> +					   GPIOD_OUT_LOW);
> +	if (IS_ERR(lcd->lr_gpio)) {
> +		dev_err(&pdev->dev, "failed to get mode[1] gpio\n");
> +		return PTR_ERR(lcd->lr_gpio);
> +	}
> +
> +	lcd->ud_gpio = devm_gpiod_get_index(&pdev->dev, "mode", 2,
> +					   GPIOD_OUT_LOW);
> +	if (IS_ERR(lcd->ud_gpio)) {
> +		dev_err(&pdev->dev, "failed to get mode[2] gpio\n");
> +		return PTR_ERR(lcd->ud_gpio);
> +	}
Do we set mo, lr ,ud gpio when we call devm_gpiod_get, or are they
unused?

> +
> +	drm_panel_init(&lcd->panel);
> +	lcd->panel.dev = &pdev->dev;
> +	lcd->panel.funcs = &ls037v7dw01_funcs;
> +
> +	return drm_panel_add(&lcd->panel);
> +}
> +
> +static int ls037v7dw01_remove(struct platform_device *pdev)
> +{
> +	struct ls037v7dw01_device *lcd = platform_get_drvdata(pdev);
> +
> +	drm_panel_remove(&lcd->panel);
> +	ls037v7dw01_disable(&lcd->panel);
> +	ls037v7dw01_unprepare(&lcd->panel);
Use drm_panel_disable(), drm_panel_unprepare()

> +
> +	return 0;
> +}
> +
> +static const struct of_device_id ls037v7dw01_of_match[] = {
> +	{ .compatible = "sharp,ls037v7dw01", },
> +	{},
{ /* sentinel */ },

> +};
> +
> +MODULE_DEVICE_TABLE(of, ls037v7dw01_of_match);
> +
> +static struct platform_driver ls037v7dw01_driver = {
> +	.probe		= ls037v7dw01_probe,
> +	.remove		= __exit_p(ls037v7dw01_remove),
> +	.driver		= {
> +		.name = "panel-sharp-ls037v7dw01",
> +		.of_match_table = ls037v7dw01_of_match,
> +	},
> +};
> +
> +module_platform_driver(ls037v7dw01_driver);
> +
> +MODULE_AUTHOR("Tomi Valkeinen <tomi.valkeinen@ti.com>");
> +MODULE_DESCRIPTION("Sharp LS037V7DW01 Panel Driver");
> +MODULE_LICENSE("GPL");
"GPL v2"?

	Sam
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