[PATCH 0/3] drm/sitronix/st7571-i2c: Add support for the ST7567 Controller

[PATCH 0/3] drm/sitronix/st7571-i2c: Add support for the ST7567 Controller

[Javier Martinez Canillas]

This patch-series adds support for the Sitronix ST7567 Controller, which is 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.

Patch #1 adds a Device Tree binding schema for the ST7567 Controller.

Patch #2 makes the "reset-gpios" property in the driver to be optional since that
isn't needed for the ST7567.

Patch #3 finally extends the st7571-i2c driver to also support the ST7567 device.


Javier Martinez Canillas (3):
  dt-bindings: display: Add Sitronix ST7567 LCD Controller
  drm/sitronix/st7571-i2c: Make the reset GPIO to be optional
  drm/sitronix/st7571-i2c: Add support for the ST7567 Controller

 .../bindings/display/sitronix,st7567.yaml     | 63 +++++++++++++++++++
 MAINTAINERS                                   |  1 +
 drivers/gpu/drm/sitronix/st7571-i2c.c         | 55 +++++++++++++++-
 3 files changed, 117 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/display/sitronix,st7567.yaml

-- 
2.49.0

base-commit: 93eacfcdfbb590d9ed6889d381d5a586dd1ac860
branch: drm-st7567

[PATCH 1/3] dt-bindings: display: Add Sitronix ST7567 LCD Controller

[Javier Martinez Canillas]

Sitronix ST7567 is a monochrome Dot Matrix LCD Controller.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
---

 .../bindings/display/sitronix,st7567.yaml     | 63 +++++++++++++++++++
 MAINTAINERS                                   |  1 +
 2 files changed, 64 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/display/sitronix,st7567.yaml

diff --git a/Documentation/devicetree/bindings/display/sitronix,st7567.yaml b/Documentation/devicetree/bindings/display/sitronix,st7567.yaml
new file mode 100644
index 000000000000..e8a5b8ad18fe
--- /dev/null
+++ b/Documentation/devicetree/bindings/display/sitronix,st7567.yaml
@@ -0,0 +1,63 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/sitronix,st7567.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Sitronix ST7567 Display Controller
+
+maintainers:
+  - Javier Martinez Canillas <javierm@redhat.com>
+
+description:
+  Sitronix ST7567 is a driver and controller for monochrome
+  dot matrix LCD panels.
+
+allOf:
+  - $ref: panel/panel-common.yaml#
+
+properties:
+  compatible:
+    const: sitronix,st7567
+
+  reg:
+    maxItems: 1
+
+  width-mm: true
+  height-mm: true
+  panel-timing: true
+
+required:
+  - compatible
+  - reg
+  - width-mm
+  - height-mm
+  - panel-timing
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        display@3f {
+            compatible = "sitronix,st7567";
+            reg = <0x3f>;
+            width-mm = <37>;
+            height-mm = <27>;
+
+            panel-timing {
+                hactive = <128>;
+                vactive = <64>;
+                hback-porch = <0>;
+                vback-porch = <0>;
+                clock-frequency = <0>;
+                hfront-porch = <0>;
+                hsync-len = <0>;
+                vfront-porch = <0>;
+                vsync-len = <0>;
+            };
+          };
+     };
diff --git a/MAINTAINERS b/MAINTAINERS
index ee2ef9d9db2a..d97e091b1742 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7835,6 +7835,7 @@ F:	drivers/gpu/drm/sitronix/st7586.c
 DRM DRIVER FOR SITRONIX ST7571 PANELS
 M:	Marcus Folkesson <marcus.folkesson@gmail.com>
 S:	Maintained
+F:	Documentation/devicetree/bindings/display/sitronix,st7567.yaml
 F:	Documentation/devicetree/bindings/display/sitronix,st7571.yaml
 F:	drivers/gpu/drm/sitronix/st7571-i2c.c
 
-- 
2.49.0

[PATCH 2/3] drm/sitronix/st7571-i2c: Make the reset GPIO to be optional

[Javier Martinez Canillas]

Some Sitronix LCD controllers (such as the ST7567) don't have a reset pin,
so lets relax this in the driver and make the reset GPIO to be optional.

The devm_gpiod_get_optional() helper is similar to devm_gpiod_get(), but
returns NULL when there isn't a reset-gpios property defined in a DT node.

The DT binding schema for "sitronix,st7571" that require a reset GPIO will
enforce the "reset-gpios" to be present, due being a required DT property.
But in the driver itself the property can be made optional if not defined.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
---

 drivers/gpu/drm/sitronix/st7571-i2c.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/sitronix/st7571-i2c.c b/drivers/gpu/drm/sitronix/st7571-i2c.c
index eec846892962..73e8db25f895 100644
--- a/drivers/gpu/drm/sitronix/st7571-i2c.c
+++ b/drivers/gpu/drm/sitronix/st7571-i2c.c
@@ -802,15 +802,19 @@ static int st7571_parse_dt(struct st7571_device *st7571)
 	st7571->nlines = dt.vactive.typ;
 	st7571->ncols = dt.hactive.typ;
 
-	st7571->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
+	st7571->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
 	if (IS_ERR(st7571->reset))
-		return PTR_ERR(st7571->reset);
+		return dev_err_probe(dev, PTR_ERR(st7571->reset),
+				     "Failed to get reset gpio\n");
 
 	return 0;
 }
 
 static void st7571_reset(struct st7571_device *st7571)
 {
+	if (!st7571->reset)
+		return;
+
 	gpiod_set_value_cansleep(st7571->reset, 1);
 	fsleep(20);
 	gpiod_set_value_cansleep(st7571->reset, 0);
-- 
2.49.0

[PATCH 3/3] drm/sitronix/st7571-i2c: Add support for the ST7567 Controller

[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@redhat.com>
---

 drivers/gpu/drm/sitronix/st7571-i2c.c | 47 +++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/drivers/gpu/drm/sitronix/st7571-i2c.c b/drivers/gpu/drm/sitronix/st7571-i2c.c
index 73e8db25f895..ea915bd5deeb 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"
@@ -820,6 +823,37 @@ 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)
 {
 	/*
@@ -964,6 +998,17 @@ static void st7571_remove(struct i2c_client *client)
 	drm_dev_unplug(&st7571->dev);
 }
 
+struct st7571_panel_data st7567_config = {
+	.init = st7567_lcd_init,
+	.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,
 	.constraints = {
@@ -976,12 +1021,14 @@ 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 },
 	{ }
 };
-- 
2.49.0

Re: [PATCH 2/3] drm/sitronix/st7571-i2c: Make the reset GPIO to be optional

[Marcus Folkesson]

[-- Attachment #1: Type: text/plain, Size: 1784 bytes --]

On Thu, Jul 10, 2025 at 12:24:34PM +0200, Javier Martinez Canillas wrote:
> Some Sitronix LCD controllers (such as the ST7567) don't have a reset pin,
> so lets relax this in the driver and make the reset GPIO to be optional.
> 
> The devm_gpiod_get_optional() helper is similar to devm_gpiod_get(), but
> returns NULL when there isn't a reset-gpios property defined in a DT node.
> 
> The DT binding schema for "sitronix,st7571" that require a reset GPIO will
> enforce the "reset-gpios" to be present, due being a required DT property.
> But in the driver itself the property can be made optional if not defined.
> 
> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
> ---
> 
>  drivers/gpu/drm/sitronix/st7571-i2c.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/sitronix/st7571-i2c.c b/drivers/gpu/drm/sitronix/st7571-i2c.c
> index eec846892962..73e8db25f895 100644
> --- a/drivers/gpu/drm/sitronix/st7571-i2c.c
> +++ b/drivers/gpu/drm/sitronix/st7571-i2c.c
> @@ -802,15 +802,19 @@ static int st7571_parse_dt(struct st7571_device *st7571)
>  	st7571->nlines = dt.vactive.typ;
>  	st7571->ncols = dt.hactive.typ;
>  
> -	st7571->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> +	st7571->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
>  	if (IS_ERR(st7571->reset))
> -		return PTR_ERR(st7571->reset);
> +		return dev_err_probe(dev, PTR_ERR(st7571->reset),
> +				     "Failed to get reset gpio\n");

devm_gpiod_get_optional() returns -ENOENT when the GPIO is not found,
and that is no error we want to propagage upwards.

Maybe something like this instead:
if (IS_ERR(st7571->reset) && IS_ERR(st7571->reset) != -ENOENT)


Best regards,
Marcus Folkesson

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Re: [PATCH 2/3] drm/sitronix/st7571-i2c: Make the reset GPIO to be optional

[Javier Martinez Canillas]

Marcus Folkesson <marcus.folkesson@gmail.com> writes:

Hello Marcus,

Thanks for your feedback.

> On Thu, Jul 10, 2025 at 12:24:34PM +0200, Javier Martinez Canillas wrote:
>> Some Sitronix LCD controllers (such as the ST7567) don't have a reset pin,
>> so lets relax this in the driver and make the reset GPIO to be optional.
>> 
>> The devm_gpiod_get_optional() helper is similar to devm_gpiod_get(), but
>> returns NULL when there isn't a reset-gpios property defined in a DT node.
>> 
>> The DT binding schema for "sitronix,st7571" that require a reset GPIO will
>> enforce the "reset-gpios" to be present, due being a required DT property.
>> But in the driver itself the property can be made optional if not defined.
>> 
>> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
>> ---
>> 
>>  drivers/gpu/drm/sitronix/st7571-i2c.c | 8 ++++++--
>>  1 file changed, 6 insertions(+), 2 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/sitronix/st7571-i2c.c b/drivers/gpu/drm/sitronix/st7571-i2c.c
>> index eec846892962..73e8db25f895 100644
>> --- a/drivers/gpu/drm/sitronix/st7571-i2c.c
>> +++ b/drivers/gpu/drm/sitronix/st7571-i2c.c
>> @@ -802,15 +802,19 @@ static int st7571_parse_dt(struct st7571_device *st7571)
>>  	st7571->nlines = dt.vactive.typ;
>>  	st7571->ncols = dt.hactive.typ;
>>  
>> -	st7571->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
>> +	st7571->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
>>  	if (IS_ERR(st7571->reset))
>> -		return PTR_ERR(st7571->reset);
>> +		return dev_err_probe(dev, PTR_ERR(st7571->reset),
>> +				     "Failed to get reset gpio\n");
>
> devm_gpiod_get_optional() returns -ENOENT when the GPIO is not found,
> and that is no error we want to propagage upwards.
>
> Maybe something like this instead:
> if (IS_ERR(st7571->reset) && IS_ERR(st7571->reset) != -ENOENT)
>

Are you sure about that? As far as I know, that is exactly the
difference between gpiod_get() and gpiod_get_optional() variants.

From the gpiod_get_optional() function helper kernel-doc [0]:

/**
 * gpiod_get_optional - obtain an optional GPIO for a given GPIO function
 * @dev: GPIO consumer, can be NULL for system-global GPIOs
 * @con_id: function within the GPIO consumer
 * @flags: optional GPIO initialization flags
 *
 * This is equivalent to gpiod_get(), except that when no GPIO was assigned to
 * the requested function it will return NULL. This is convenient for drivers
 * that need to handle optional GPIOs.
 *
 * Returns:
 * The GPIO descriptor corresponding to the function @con_id of device
 * dev, NULL if no GPIO has been assigned to the requested function, or
 * another IS_ERR() code if an error occurred while trying to acquire the GPIO.
 */

while the gpiod_get() kernel-doc says the following:

/**
 * gpiod_get - obtain a GPIO for a given GPIO function
 * @dev:	GPIO consumer, can be NULL for system-global GPIOs
 * @con_id:	function within the GPIO consumer
 * @flags:	optional GPIO initialization flags
 *
 * Returns:
 * The GPIO descriptor corresponding to the function @con_id of device
 * dev, -ENOENT if no GPIO has been assigned to the requested function, or
 * another IS_ERR() code if an error occurred while trying to acquire the GPIO.
 */

[0]: https://elixir.bootlin.com/linux/v6.16-rc5/source/drivers/gpio/gpiolib.c#L4755

>
> Best regards,
> Marcus Folkesson

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat

Re: [PATCH 2/3] drm/sitronix/st7571-i2c: Make the reset GPIO to be optional

[Marcus Folkesson]

[-- Attachment #1: Type: text/plain, Size: 1956 bytes --]

Hello Javier,

On Thu, Jul 10, 2025 at 01:00:41PM +0200, Javier Martinez Canillas wrote:
> >
> > devm_gpiod_get_optional() returns -ENOENT when the GPIO is not found,
> > and that is no error we want to propagage upwards.
> >
> > Maybe something like this instead:
> > if (IS_ERR(st7571->reset) && IS_ERR(st7571->reset) != -ENOENT)
> >
> 
> Are you sure about that? As far as I know, that is exactly the
> difference between gpiod_get() and gpiod_get_optional() variants.
> 
> From the gpiod_get_optional() function helper kernel-doc [0]:
> 
> /**
>  * gpiod_get_optional - obtain an optional GPIO for a given GPIO function
>  * @dev: GPIO consumer, can be NULL for system-global GPIOs
>  * @con_id: function within the GPIO consumer
>  * @flags: optional GPIO initialization flags
>  *
>  * This is equivalent to gpiod_get(), except that when no GPIO was assigned to
>  * the requested function it will return NULL. This is convenient for drivers
>  * that need to handle optional GPIOs.
>  *
>  * Returns:
>  * The GPIO descriptor corresponding to the function @con_id of device
>  * dev, NULL if no GPIO has been assigned to the requested function, or
>  * another IS_ERR() code if an error occurred while trying to acquire the GPIO.
>  */
> 
> while the gpiod_get() kernel-doc says the following:
> 
> /**
>  * gpiod_get - obtain a GPIO for a given GPIO function
>  * @dev:	GPIO consumer, can be NULL for system-global GPIOs
>  * @con_id:	function within the GPIO consumer
>  * @flags:	optional GPIO initialization flags
>  *
>  * Returns:
>  * The GPIO descriptor corresponding to the function @con_id of device
>  * dev, -ENOENT if no GPIO has been assigned to the requested function, or
>  * another IS_ERR() code if an error occurred while trying to acquire the GPIO.
>  */
> 

You are completely righ.

Reviewed-by: Marcus Folkesson <marcus.folkesson@gmail.com>

Best regards,
Marcus Folkesson

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Re: [PATCH 1/3] dt-bindings: display: Add Sitronix ST7567 LCD Controller

[Rob Herring (Arm)]

On Thu, 10 Jul 2025 12:24:33 +0200, Javier Martinez Canillas wrote:
> Sitronix ST7567 is a monochrome Dot Matrix LCD Controller.
> 
> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
> ---
> 
>  .../bindings/display/sitronix,st7567.yaml     | 63 +++++++++++++++++++
>  MAINTAINERS                                   |  1 +
>  2 files changed, 64 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/display/sitronix,st7567.yaml
> 

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>

Re: [PATCH 2/3] drm/sitronix/st7571-i2c: Make the reset GPIO to be optional

[Javier Martinez Canillas]

Marcus Folkesson <marcus.folkesson@gmail.com> writes:

Hello Marcus,

> Hello Javier,
>
> On Thu, Jul 10, 2025 at 01:00:41PM +0200, Javier Martinez Canillas wrote:
>> >
>> > devm_gpiod_get_optional() returns -ENOENT when the GPIO is not found,
>> > and that is no error we want to propagage upwards.
>> >
>> > Maybe something like this instead:
>> > if (IS_ERR(st7571->reset) && IS_ERR(st7571->reset) != -ENOENT)
>> >
>> 
>> Are you sure about that? As far as I know, that is exactly the
>> difference between gpiod_get() and gpiod_get_optional() variants.
>> 
>> From the gpiod_get_optional() function helper kernel-doc [0]:
>> 
>> /**
>>  * gpiod_get_optional - obtain an optional GPIO for a given GPIO function
>>  * @dev: GPIO consumer, can be NULL for system-global GPIOs
>>  * @con_id: function within the GPIO consumer
>>  * @flags: optional GPIO initialization flags
>>  *
>>  * This is equivalent to gpiod_get(), except that when no GPIO was assigned to
>>  * the requested function it will return NULL. This is convenient for drivers
>>  * that need to handle optional GPIOs.
>>  *
>>  * Returns:
>>  * The GPIO descriptor corresponding to the function @con_id of device
>>  * dev, NULL if no GPIO has been assigned to the requested function, or
>>  * another IS_ERR() code if an error occurred while trying to acquire the GPIO.
>>  */
>> 
>> while the gpiod_get() kernel-doc says the following:
>> 
>> /**
>>  * gpiod_get - obtain a GPIO for a given GPIO function
>>  * @dev:	GPIO consumer, can be NULL for system-global GPIOs
>>  * @con_id:	function within the GPIO consumer
>>  * @flags:	optional GPIO initialization flags
>>  *
>>  * Returns:
>>  * The GPIO descriptor corresponding to the function @con_id of device
>>  * dev, -ENOENT if no GPIO has been assigned to the requested function, or
>>  * another IS_ERR() code if an error occurred while trying to acquire the GPIO.
>>  */
>> 
>
> You are completely righ.
>
> Reviewed-by: Marcus Folkesson <marcus.folkesson@gmail.com>
>

Thanks for your review! Do you plan to look at the other patches too ?

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat

Re: [PATCH 0/3] drm/sitronix/st7571-i2c: Add support for the ST7567 Controller

[Marcus Folkesson]

[-- Attachment #1: Type: text/plain, Size: 1244 bytes --]

Hello Javier,


On Thu, Jul 10, 2025 at 12:24:32PM +0200, Javier Martinez Canillas wrote:
> This patch-series adds support for the Sitronix ST7567 Controller, which is 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.
> 
> Patch #1 adds a Device Tree binding schema for the ST7567 Controller.
> 
> Patch #2 makes the "reset-gpios" property in the driver to be optional since that
> isn't needed for the ST7567.
> 
> Patch #3 finally extends the st7571-i2c driver to also support the ST7567 device.
> 
> 
> Javier Martinez Canillas (3):
>   dt-bindings: display: Add Sitronix ST7567 LCD Controller
>   drm/sitronix/st7571-i2c: Make the reset GPIO to be optional
>   drm/sitronix/st7571-i2c: Add support for the ST7567 Controller

For all patches in this series:

Reviewed-by: Marcus Folkesson <marcus.folkesson@gmail.com>

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Re: [PATCH 0/3] drm/sitronix/st7571-i2c: Add support for the ST7567 Controller

[Javier Martinez Canillas]

Marcus Folkesson <marcus.folkesson@gmail.com> writes:

Hello Marcus,

> Hello Javier,
>
>
> On Thu, Jul 10, 2025 at 12:24:32PM +0200, Javier Martinez Canillas wrote:
>> This patch-series adds support for the Sitronix ST7567 Controller, which is 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.
>> 
>> Patch #1 adds a Device Tree binding schema for the ST7567 Controller.
>> 
>> Patch #2 makes the "reset-gpios" property in the driver to be optional since that
>> isn't needed for the ST7567.
>> 
>> Patch #3 finally extends the st7571-i2c driver to also support the ST7567 device.
>> 
>> 
>> Javier Martinez Canillas (3):
>>   dt-bindings: display: Add Sitronix ST7567 LCD Controller
>>   drm/sitronix/st7571-i2c: Make the reset GPIO to be optional
>>   drm/sitronix/st7571-i2c: Add support for the ST7567 Controller
>
> For all patches in this series:
>
> Reviewed-by: Marcus Folkesson <marcus.folkesson@gmail.com>

Thanks! I'll merge this patch series next week then, since I also got an
ack from a DT maintainer.

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat

Re: [PATCH 2/3] drm/sitronix/st7571-i2c: Make the reset GPIO to be optional

[Thomas Zimmermann]

Hi

Am 10.07.25 um 12:24 schrieb Javier Martinez Canillas:
> Some Sitronix LCD controllers (such as the ST7567) don't have a reset pin,
> so lets relax this in the driver and make the reset GPIO to be optional.
>
> The devm_gpiod_get_optional() helper is similar to devm_gpiod_get(), but
> returns NULL when there isn't a reset-gpios property defined in a DT node.
>
> The DT binding schema for "sitronix,st7571" that require a reset GPIO will
> enforce the "reset-gpios" to be present, due being a required DT property.
> But in the driver itself the property can be made optional if not defined.
>
> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
> ---
>
>   drivers/gpu/drm/sitronix/st7571-i2c.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/sitronix/st7571-i2c.c b/drivers/gpu/drm/sitronix/st7571-i2c.c
> index eec846892962..73e8db25f895 100644
> --- a/drivers/gpu/drm/sitronix/st7571-i2c.c
> +++ b/drivers/gpu/drm/sitronix/st7571-i2c.c
> @@ -802,15 +802,19 @@ static int st7571_parse_dt(struct st7571_device *st7571)
>   	st7571->nlines = dt.vactive.typ;
>   	st7571->ncols = dt.hactive.typ;
>   
> -	st7571->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> +	st7571->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
>   	if (IS_ERR(st7571->reset))
> -		return PTR_ERR(st7571->reset);
> +		return dev_err_probe(dev, PTR_ERR(st7571->reset),
> +				     "Failed to get reset gpio\n");
>   
>   	return 0;
>   }
>   
>   static void st7571_reset(struct st7571_device *st7571)
>   {
> +	if (!st7571->reset)
> +		return;
> +

My interpretation of this function is that calling it guarantees a 
device reset (or an error). So I'd push this test into the caller.

Best regards
Thomas

>   	gpiod_set_value_cansleep(st7571->reset, 1);
>   	fsleep(20);
>   	gpiod_set_value_cansleep(st7571->reset, 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)

Re: [PATCH 2/3] drm/sitronix/st7571-i2c: Make the reset GPIO to be optional

[Thomas Zimmermann]

Hi

Am 10.07.25 um 12:24 schrieb Javier Martinez Canillas:
> Some Sitronix LCD controllers (such as the ST7567) don't have a reset pin,
> so lets relax this in the driver and make the reset GPIO to be optional.
>
> The devm_gpiod_get_optional() helper is similar to devm_gpiod_get(), but
> returns NULL when there isn't a reset-gpios property defined in a DT node.
>
> The DT binding schema for "sitronix,st7571" that require a reset GPIO will
> enforce the "reset-gpios" to be present, due being a required DT property.
> But in the driver itself the property can be made optional if not defined.
>
> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
> ---
>
>   drivers/gpu/drm/sitronix/st7571-i2c.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/sitronix/st7571-i2c.c b/drivers/gpu/drm/sitronix/st7571-i2c.c
> index eec846892962..73e8db25f895 100644
> --- a/drivers/gpu/drm/sitronix/st7571-i2c.c
> +++ b/drivers/gpu/drm/sitronix/st7571-i2c.c
> @@ -802,15 +802,19 @@ static int st7571_parse_dt(struct st7571_device *st7571)
>   	st7571->nlines = dt.vactive.typ;
>   	st7571->ncols = dt.hactive.typ;
>   
> -	st7571->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> +	st7571->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
>   	if (IS_ERR(st7571->reset))
> -		return PTR_ERR(st7571->reset);
> +		return dev_err_probe(dev, PTR_ERR(st7571->reset),
> +				     "Failed to get reset gpio\n");

There's struct st7571_panel_data. It could store a flag signalling the 
expected behavior.

With more effort the panel_data could store a dedicated parse_dt pointer 
for each panel type. ASAICT the st7567 features a subset of the other 
type. So there might not be much code duplication.

Best regards
Thomas

>   
>   	return 0;
>   }
>   
>   static void st7571_reset(struct st7571_device *st7571)
>   {
> +	if (!st7571->reset)
> +		return;
> +
>   	gpiod_set_value_cansleep(st7571->reset, 1);
>   	fsleep(20);
>   	gpiod_set_value_cansleep(st7571->reset, 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)

Re: [PATCH 2/3] drm/sitronix/st7571-i2c: Make the reset GPIO to be optional

[Javier Martinez Canillas]

Thomas Zimmermann <tzimmermann@suse.de> writes:

Hello Thomas,

> Hi
>
> Am 10.07.25 um 12:24 schrieb Javier Martinez Canillas:
>> Some Sitronix LCD controllers (such as the ST7567) don't have a reset pin,
>> so lets relax this in the driver and make the reset GPIO to be optional.
>>
>> The devm_gpiod_get_optional() helper is similar to devm_gpiod_get(), but
>> returns NULL when there isn't a reset-gpios property defined in a DT node.
>>
>> The DT binding schema for "sitronix,st7571" that require a reset GPIO will
>> enforce the "reset-gpios" to be present, due being a required DT property.
>> But in the driver itself the property can be made optional if not defined.
>>
>> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
>> ---
>>
>>   drivers/gpu/drm/sitronix/st7571-i2c.c | 8 ++++++--
>>   1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/sitronix/st7571-i2c.c b/drivers/gpu/drm/sitronix/st7571-i2c.c
>> index eec846892962..73e8db25f895 100644
>> --- a/drivers/gpu/drm/sitronix/st7571-i2c.c
>> +++ b/drivers/gpu/drm/sitronix/st7571-i2c.c
>> @@ -802,15 +802,19 @@ static int st7571_parse_dt(struct st7571_device *st7571)
>>   	st7571->nlines = dt.vactive.typ;
>>   	st7571->ncols = dt.hactive.typ;
>>   
>> -	st7571->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
>> +	st7571->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
>>   	if (IS_ERR(st7571->reset))
>> -		return PTR_ERR(st7571->reset);
>> +		return dev_err_probe(dev, PTR_ERR(st7571->reset),
>> +				     "Failed to get reset gpio\n");
>>   
>>   	return 0;
>>   }
>>   
>>   static void st7571_reset(struct st7571_device *st7571)
>>   {
>> +	if (!st7571->reset)
>> +		return;
>> +
>
> My interpretation of this function is that calling it guarantees a 
> device reset (or an error). So I'd push this test into the caller.
>

That's a good point. I'll then do the check in the caller.

Actually... at the end I didn't need a st7571_reset() call for ST7567
since it has its own struct st7571_panel_data .init callback function.

So I can just drop the test for st7571->reset being NULL.

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat

Re: [PATCH 2/3] drm/sitronix/st7571-i2c: Make the reset GPIO to be optional

[Javier Martinez Canillas]

Thomas Zimmermann <tzimmermann@suse.de> writes:

> Hi
>
> Am 10.07.25 um 12:24 schrieb Javier Martinez Canillas:
>> Some Sitronix LCD controllers (such as the ST7567) don't have a reset pin,
>> so lets relax this in the driver and make the reset GPIO to be optional.
>>
>> The devm_gpiod_get_optional() helper is similar to devm_gpiod_get(), but
>> returns NULL when there isn't a reset-gpios property defined in a DT node.
>>
>> The DT binding schema for "sitronix,st7571" that require a reset GPIO will
>> enforce the "reset-gpios" to be present, due being a required DT property.
>> But in the driver itself the property can be made optional if not defined.
>>
>> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
>> ---
>>
>>   drivers/gpu/drm/sitronix/st7571-i2c.c | 8 ++++++--
>>   1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/sitronix/st7571-i2c.c b/drivers/gpu/drm/sitronix/st7571-i2c.c
>> index eec846892962..73e8db25f895 100644
>> --- a/drivers/gpu/drm/sitronix/st7571-i2c.c
>> +++ b/drivers/gpu/drm/sitronix/st7571-i2c.c
>> @@ -802,15 +802,19 @@ static int st7571_parse_dt(struct st7571_device *st7571)
>>   	st7571->nlines = dt.vactive.typ;
>>   	st7571->ncols = dt.hactive.typ;
>>   
>> -	st7571->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
>> +	st7571->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
>>   	if (IS_ERR(st7571->reset))
>> -		return PTR_ERR(st7571->reset);
>> +		return dev_err_probe(dev, PTR_ERR(st7571->reset),
>> +				     "Failed to get reset gpio\n");
>
> There's struct st7571_panel_data. It could store a flag signalling the 
> expected behavior.
>

Indeed.

> With more effort the panel_data could store a dedicated parse_dt pointer 
> for each panel type. ASAICT the st7567 features a subset of the other 
> type. So there might not be much code duplication.
>

This is a good idea too. I think that will do that for v2.

Thanks a lot for your feedback!

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat