linux-kernel - Re: [PATCH v2 5/5] drm/sitronix/st7571-i2c: Add support for the ST7567 Controller

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Message-ID: <678d7564-3736-4c5e-9d32-d107eb76af28@suse.de>
Date: Mon, 14 Jul 2025 14:11:07 +0200
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Javier Martinez Canillas <javierm@...hat.com>,
 linux-kernel@...r.kernel.org
Cc: ipedrosa@...hat.com, Marcus Folkesson <marcus.folkesson@...il.com>,
 David Airlie <airlied@...il.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Simona Vetter <simona@...ll.ch>,
 dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v2 5/5] drm/sitronix/st7571-i2c: Add support for the
 ST7567 Controller



Am 14.07.25 um 12:44 schrieb Javier Martinez Canillas:
> The Sitronix ST7567 is a monochrome Dot Matrix LCD Controller that has SPI,
> I2C and parallel interfaces. The st7571-i2c driver only has support for I2C
> so displays using other transport interfaces are currently not supported.
>
> The DRM_FORMAT_R1 pixel format and data commands are the same than what
> is used by the ST7571 controller, so only is needed a different callback
> that implements the expected initialization sequence for the ST7567 chip.
>
> Signed-off-by: Javier Martinez Canillas <javierm@...hat.com>
> Reviewed-by: Marcus Folkesson <marcus.folkesson@...il.com>

Reviewed-by: Thomas Zimmermann <tzimmermann@...e.de>

> ---
>
> Changes in v2:
> - Use a different parse DT function (Thomas Zimmermann).
>
>   drivers/gpu/drm/sitronix/st7571-i2c.c | 74 +++++++++++++++++++++++++++
>   1 file changed, 74 insertions(+)
>
> diff --git a/drivers/gpu/drm/sitronix/st7571-i2c.c b/drivers/gpu/drm/sitronix/st7571-i2c.c
> index f9c4fedb3cca..1b820ff6a9dd 100644
> --- a/drivers/gpu/drm/sitronix/st7571-i2c.c
> +++ b/drivers/gpu/drm/sitronix/st7571-i2c.c
> @@ -68,6 +68,9 @@
>   #define ST7571_SET_COLOR_MODE(c)		(0x10 | FIELD_PREP(GENMASK(0, 0), (c)))
>   #define ST7571_COMMAND_SET_NORMAL		(0x00)
>   
> +/* ST7567 commands */
> +#define ST7567_SET_LCD_BIAS(m) (0xa2 | FIELD_PREP(GENMASK(0, 0), (m)))
> +
>   #define ST7571_PAGE_HEIGHT 8
>   
>   #define DRIVER_NAME "st7571"
> @@ -774,6 +777,32 @@ static int st7571_validate_parameters(struct st7571_device *st7571)
>   	return 0;
>   }
>   
> +static int st7567_parse_dt(struct st7571_device *st7567)
> +{
> +	struct device *dev = &st7567->client->dev;
> +	struct device_node *np = dev->of_node;
> +	struct display_timing dt;
> +	int ret;
> +
> +	ret = of_get_display_timing(np, "panel-timing", &dt);
> +	if (ret) {
> +		dev_err(dev, "Failed to get display timing from DT\n");
> +		return ret;
> +	}
> +
> +	of_property_read_u32(np, "width-mm", &st7567->width_mm);
> +	of_property_read_u32(np, "height-mm", &st7567->height_mm);
> +
> +	st7567->pformat = &st7571_monochrome;
> +	st7567->bpp = 1;
> +
> +	st7567->startline = dt.vfront_porch.typ;
> +	st7567->nlines = dt.vactive.typ;
> +	st7567->ncols = dt.hactive.typ;
> +
> +	return 0;
> +}
> +
>   static int st7571_parse_dt(struct st7571_device *st7571)
>   {
>   	struct device *dev = &st7571->client->dev;
> @@ -819,6 +848,37 @@ static void st7571_reset(struct st7571_device *st7571)
>   	gpiod_set_value_cansleep(st7571->reset, 0);
>   }
>   
> +static int st7567_lcd_init(struct st7571_device *st7567)
> +{
> +	/*
> +	 * Most of the initialization sequence is taken directly from the
> +	 * referential initial code in the ST7567 datasheet.
> +	 */
> +	u8 commands[] = {
> +		ST7571_DISPLAY_OFF,
> +
> +		ST7567_SET_LCD_BIAS(1),
> +
> +		ST7571_SET_SEG_SCAN_DIR(0),
> +		ST7571_SET_COM_SCAN_DIR(1),
> +
> +		ST7571_SET_REGULATOR_REG(4),
> +		ST7571_SET_CONTRAST_MSB,
> +		ST7571_SET_CONTRAST_LSB(0x20),
> +
> +		ST7571_SET_START_LINE_MSB,
> +		ST7571_SET_START_LINE_LSB(st7567->startline),
> +
> +		ST7571_SET_POWER(0x4),	/* Power Control, VC: ON, VR: OFF, VF: OFF */
> +		ST7571_SET_POWER(0x6),	/* Power Control, VC: ON, VR: ON, VF: OFF */
> +		ST7571_SET_POWER(0x7),	/* Power Control, VC: ON, VR: ON, VF: ON */
> +
> +		ST7571_SET_ENTIRE_DISPLAY_ON(0),
> +	};
> +
> +	return st7571_send_command_list(st7567, commands, ARRAY_SIZE(commands));
> +}
> +
>   static int st7571_lcd_init(struct st7571_device *st7571)
>   {
>   	/*
> @@ -963,6 +1023,18 @@ static void st7571_remove(struct i2c_client *client)
>   	drm_dev_unplug(&st7571->dev);
>   }
>   
> +struct st7571_panel_data st7567_config = {
> +	.init = st7567_lcd_init,
> +	.parse_dt = st7567_parse_dt,
> +	.constraints = {
> +		.min_nlines = 1,
> +		.max_nlines = 64,
> +		.min_ncols = 128,
> +		.max_ncols = 128,
> +		.support_grayscale = false,
> +	},
> +};
> +
>   struct st7571_panel_data st7571_config = {
>   	.init = st7571_lcd_init,
>   	.parse_dt = st7571_parse_dt,
> @@ -976,12 +1048,14 @@ struct st7571_panel_data st7571_config = {
>   };
>   
>   static const struct of_device_id st7571_of_match[] = {
> +	{ .compatible = "sitronix,st7567", .data = &st7567_config },
>   	{ .compatible = "sitronix,st7571", .data = &st7571_config },
>   	{},
>   };
>   MODULE_DEVICE_TABLE(of, st7571_of_match);
>   
>   static const struct i2c_device_id st7571_id[] = {
> +	{ "st7567", 0 },
>   	{ "st7571", 0 },
>   	{ }
>   };

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)