[PATCH v4 0/6] Add display support on the stm32f746-disco board

[PATCH v4 0/6] Add display support on the stm32f746-disco board

[Dario Binacchi]

The series adds support for the display on the stm32f746-disco board,
along with a generic patch that adds the "bpp" parameter to the stm-drm
module. The intention is to allow users to size, within certain limits,
the memory footprint required by the framebuffer.

Changes in v4:
- Use DTS property instead of module parameter to set the framebuffer bit depth.

Changes in v3:
- rename ltdc-pins-a-0 to ltdc-0.
- drop [4/6] dt-bindings: display: simple: add Rocktech RK043FN48H
  Applied to https://anongit.freedesktop.org/git/drm/drm-misc.git (drm-misc-next):
  https://cgit.freedesktop.org/drm/drm-misc/commit/?id=c42a37a27c777d63961dd634a30f7c887949491a
- drop [5/6] drm/panel: simple: add support for Rocktech RK043FN48H panel
  Applied to https://anongit.freedesktop.org/git/drm/drm-misc.git (drm-misc-next)
  https://cgit.freedesktop.org/drm/drm-misc/commit/?id=13cdd12a9f934158f4ec817cf048fcb4384aa9dc

Dario Binacchi (6):
  ARM: dts: stm32: add ltdc support on stm32f746 MCU
  ARM: dts: stm32: add pin map for LTDC on stm32f7
  ARM: dts: stm32: support display on stm32f746-disco board
  dt-bindings: display: stm32-ltdc: add optional st,fb-bpp property
  ARM: dts: stm32: set framebuffer bit depth on stm32f746-disco
  drm/stm: set framebuffer bit depth through DTS property

 .../bindings/display/st,stm32-ltdc.yaml       |  6 +++
 arch/arm/boot/dts/stm32f7-pinctrl.dtsi        | 35 +++++++++++++
 arch/arm/boot/dts/stm32f746-disco.dts         | 52 +++++++++++++++++++
 arch/arm/boot/dts/stm32f746.dtsi              | 10 ++++
 drivers/gpu/drm/stm/drv.c                     |  6 ++-
 5 files changed, 108 insertions(+), 1 deletion(-)

-- 
2.32.0

[PATCH v4 1/6] ARM: dts: stm32: add ltdc support on stm32f746 MCU

[Dario Binacchi]

Add LTDC (Lcd-tft Display Controller) support.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
---

(no changes since v1)

 arch/arm/boot/dts/stm32f746.dtsi | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/arm/boot/dts/stm32f746.dtsi b/arch/arm/boot/dts/stm32f746.dtsi
index dc868e6da40e..9c4ba0b7f239 100644
--- a/arch/arm/boot/dts/stm32f746.dtsi
+++ b/arch/arm/boot/dts/stm32f746.dtsi
@@ -507,6 +507,16 @@ pwm {
 			};
 		};
 
+		ltdc: display-controller@40016800 {
+			compatible = "st,stm32-ltdc";
+			reg = <0x40016800 0x200>;
+			interrupts = <88>, <89>;
+			resets = <&rcc STM32F7_APB2_RESET(LTDC)>;
+			clocks = <&rcc 1 CLK_LCD>;
+			clock-names = "lcd";
+			status = "disabled";
+		};
+
 		pwrcfg: power-config@40007000 {
 			compatible = "st,stm32-power-config", "syscon";
 			reg = <0x40007000 0x400>;
-- 
2.32.0

[PATCH v4 2/6] ARM: dts: stm32: add pin map for LTDC on stm32f7

[Dario Binacchi]

Add pin configurations for using LTDC (LCD-tft Display Controller) on
stm32f746-disco board.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>

---

(no changes since v3)

Changes in v3:
- rename ltdc-pins-a-0 to ltdc-0.

 arch/arm/boot/dts/stm32f7-pinctrl.dtsi | 35 ++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/arch/arm/boot/dts/stm32f7-pinctrl.dtsi b/arch/arm/boot/dts/stm32f7-pinctrl.dtsi
index 9f65403295ca..36dad40dd0c7 100644
--- a/arch/arm/boot/dts/stm32f7-pinctrl.dtsi
+++ b/arch/arm/boot/dts/stm32f7-pinctrl.dtsi
@@ -365,6 +365,41 @@ pins2 {
 					bias-pull-up;
 				};
 			};
+
+
+			ltdc_pins_a: ltdc-0 {
+				pins {
+					pinmux = <STM32_PINMUX('E', 4, AF14)>, /* LCD_B0 */
+						 <STM32_PINMUX('G',12, AF9)>,  /* LCD_B4 */
+						 <STM32_PINMUX('I', 9, AF14)>, /* LCD_VSYNC */
+						 <STM32_PINMUX('I',10, AF14)>, /* LCD_HSYNC */
+						 <STM32_PINMUX('I',14, AF14)>, /* LCD_CLK */
+						 <STM32_PINMUX('I',15, AF14)>, /* LCD_R0 */
+						 <STM32_PINMUX('J', 0, AF14)>, /* LCD_R1 */
+						 <STM32_PINMUX('J', 1, AF14)>, /* LCD_R2 */
+						 <STM32_PINMUX('J', 2, AF14)>, /* LCD_R3 */
+						 <STM32_PINMUX('J', 3, AF14)>, /* LCD_R4 */
+						 <STM32_PINMUX('J', 4, AF14)>, /* LCD_R5 */
+						 <STM32_PINMUX('J', 5, AF14)>, /* LCD_R6 */
+						 <STM32_PINMUX('J', 6, AF14)>, /* LCD_R7 */
+						 <STM32_PINMUX('J', 7, AF14)>, /* LCD_G0 */
+						 <STM32_PINMUX('J', 8, AF14)>, /* LCD_G1 */
+						 <STM32_PINMUX('J', 9, AF14)>, /* LCD_G2 */
+						 <STM32_PINMUX('J',10, AF14)>, /* LCD_G3 */
+						 <STM32_PINMUX('J',11, AF14)>, /* LCD_G4 */
+						 <STM32_PINMUX('J',13, AF14)>, /* LCD_B1 */
+						 <STM32_PINMUX('J',14, AF14)>, /* LCD_B2 */
+						 <STM32_PINMUX('J',15, AF14)>, /* LCD_B3 */
+						 <STM32_PINMUX('K', 0, AF14)>, /* LCD_G5 */
+						 <STM32_PINMUX('K', 1, AF14)>, /* LCD_G6 */
+						 <STM32_PINMUX('K', 2, AF14)>, /* LCD_G7 */
+						 <STM32_PINMUX('K', 4, AF14)>, /* LCD_B5 */
+						 <STM32_PINMUX('K', 5, AF14)>, /* LCD_B6 */
+						 <STM32_PINMUX('K', 6, AF14)>, /* LCD_B7 */
+						 <STM32_PINMUX('K', 7, AF14)>; /* LCD_DE */
+					slew-rate = <2>;
+				};
+			};
 		};
 	};
 };
-- 
2.32.0

[PATCH v4 3/6] ARM: dts: stm32: support display on stm32f746-disco board

[Dario Binacchi]

Add support to Rocktech RK043FN48H display on stm32f746-disco board.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
---

(no changes since v1)

 arch/arm/boot/dts/stm32f746-disco.dts | 51 +++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/arch/arm/boot/dts/stm32f746-disco.dts b/arch/arm/boot/dts/stm32f746-disco.dts
index c11616ed5fc6..cda423b6a874 100644
--- a/arch/arm/boot/dts/stm32f746-disco.dts
+++ b/arch/arm/boot/dts/stm32f746-disco.dts
@@ -60,10 +60,41 @@ memory@c0000000 {
 		reg = <0xC0000000 0x800000>;
 	};
 
+	reserved-memory {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges;
+
+		linux,cma {
+			compatible = "shared-dma-pool";
+			no-map;
+			size = <0x80000>;
+			linux,dma-default;
+		};
+	};
+
 	aliases {
 		serial0 = &usart1;
 	};
 
+	backlight: backlight {
+		compatible = "gpio-backlight";
+		gpios = <&gpiok 3 GPIO_ACTIVE_HIGH>;
+		status = "okay";
+	};
+
+	panel_rgb: panel-rgb {
+		compatible = "rocktech,rk043fn48h";
+		backlight = <&backlight>;
+		enable-gpios = <&gpioi 12 GPIO_ACTIVE_HIGH>;
+		status = "okay";
+		port {
+			panel_in_rgb: endpoint {
+				remote-endpoint = <&ltdc_out_rgb>;
+			};
+		};
+	};
+
 	usbotg_hs_phy: usb-phy {
 		#phy-cells = <0>;
 		compatible = "usb-nop-xceiv";
@@ -99,6 +130,26 @@ &i2c1 {
 	status = "okay";
 };
 
+&dma1 {
+	status = "okay";
+};
+
+&dma2 {
+	status = "okay";
+};
+
+&ltdc {
+	pinctrl-0 = <&ltdc_pins_a>;
+	pinctrl-names = "default";
+	status = "okay";
+
+	port {
+		ltdc_out_rgb: endpoint {
+			remote-endpoint = <&panel_in_rgb>;
+		};
+	};
+};
+
 &sdio1 {
 	status = "okay";
 	vmmc-supply = <&mmc_vcard>;
-- 
2.32.0

[PATCH v4 4/6] dt-bindings: display: stm32-ltdc: add optional st,fb-bpp property

[Dario Binacchi]

Boards that use the STM32F{4,7} series have limited amounts of RAM. The
added property allows to size, within certain limits, the memory footprint
required by the framebuffer.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
---

(no changes since v1)

 .../devicetree/bindings/display/st,stm32-ltdc.yaml          | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/st,stm32-ltdc.yaml b/Documentation/devicetree/bindings/display/st,stm32-ltdc.yaml
index d6ea4d62a2cf..1c3a3653579f 100644
--- a/Documentation/devicetree/bindings/display/st,stm32-ltdc.yaml
+++ b/Documentation/devicetree/bindings/display/st,stm32-ltdc.yaml
@@ -42,6 +42,12 @@ properties:
       - for internal dpi input of the MIPI DSI host controller.
       Note: These 2 endpoints cannot be activated simultaneously.
 
+  st,fb-bpp:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: |
+      bit depth of framebuffer (8, 16 or 32)
+    maxItems: 1
+
 required:
   - compatible
   - reg
-- 
2.32.0

Re: [PATCH v4 4/6] dt-bindings: display: stm32-ltdc: add optional st,fb-bpp property

[Rob Herring]

On Mon, 19 Jun 2023 18:55:23 +0200, Dario Binacchi wrote:
> Boards that use the STM32F{4,7} series have limited amounts of RAM. The
> added property allows to size, within certain limits, the memory footprint
> required by the framebuffer.
> 
> Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
> ---
> 
> (no changes since v1)
> 
>  .../devicetree/bindings/display/st,stm32-ltdc.yaml          | 6 ++++++
>  1 file changed, 6 insertions(+)
> 

My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
on your patch (DT_CHECKER_FLAGS is new in v5.13):

yamllint warnings/errors:

dtschema/dtc warnings/errors:
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/display/st,stm32-ltdc.yaml: properties:st,fb-bpp:maxItems: False schema does not allow 1
	from schema $id: http://devicetree.org/meta-schemas/core.yaml#

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20230619165525.1035243-5-dario.binacchi@amarulasolutions.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.

Re: [PATCH v4 4/6] dt-bindings: display: stm32-ltdc: add optional st,fb-bpp property

[Conor Dooley]

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Hey,

On Mon, Jun 19, 2023 at 06:55:23PM +0200, Dario Binacchi wrote:
> Boards that use the STM32F{4,7} series have limited amounts of RAM. The
> added property allows to size, within certain limits, the memory footprint
> required by the framebuffer.

Hmm, this sounds quite a lot like "software policy", since the actual
display doesn't have these limitations. Rob, Krzysztof?

> 
> Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
> ---
> 
> (no changes since v1)

Really?
https://lore.kernel.org/all/?q=dfn:st,stm32-ltdc.yaml%20

You sure this shouldn't be "new in v4"?

>  .../devicetree/bindings/display/st,stm32-ltdc.yaml          | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/display/st,stm32-ltdc.yaml b/Documentation/devicetree/bindings/display/st,stm32-ltdc.yaml
> index d6ea4d62a2cf..1c3a3653579f 100644
> --- a/Documentation/devicetree/bindings/display/st,stm32-ltdc.yaml
> +++ b/Documentation/devicetree/bindings/display/st,stm32-ltdc.yaml
> @@ -42,6 +42,12 @@ properties:
>        - for internal dpi input of the MIPI DSI host controller.
>        Note: These 2 endpoints cannot be activated simultaneously.
>  
> +  st,fb-bpp:

Is there not a more understandable property name than this?
Maybe I just had to think about it because fbdev stuff aint something
I've worked with...

> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    description: |
> +      bit depth of framebuffer (8, 16 or 32)
> +    maxItems: 1

Why not make it an enum, since there are only 4 values?

Cheers,
Conor.

> +
>  required:
>    - compatible
>    - reg
> -- 
> 2.32.0
> 

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Re: [PATCH v4 4/6] dt-bindings: display: stm32-ltdc: add optional st,fb-bpp property

[Rob Herring]

On Mon, Jun 19, 2023 at 09:18:25PM +0100, Conor Dooley wrote:
> Hey,
> 
> On Mon, Jun 19, 2023 at 06:55:23PM +0200, Dario Binacchi wrote:
> > Boards that use the STM32F{4,7} series have limited amounts of RAM. The
> > added property allows to size, within certain limits, the memory footprint
> > required by the framebuffer.
> 
> Hmm, this sounds quite a lot like "software policy", since the actual
> display doesn't have these limitations. Rob, Krzysztof?

Indeed. This doesn't belong in DT.

Rob

[PATCH v4 5/6] ARM: dts: stm32: set framebuffer bit depth on stm32f746-disco

[Dario Binacchi]

The board uses a limited amounts of RAM. The added property halves the
memory footprint required by the framebuffer.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
---

(no changes since v1)

 arch/arm/boot/dts/stm32f746-disco.dts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/boot/dts/stm32f746-disco.dts b/arch/arm/boot/dts/stm32f746-disco.dts
index cda423b6a874..36612b4c2504 100644
--- a/arch/arm/boot/dts/stm32f746-disco.dts
+++ b/arch/arm/boot/dts/stm32f746-disco.dts
@@ -142,6 +142,7 @@ &ltdc {
 	pinctrl-0 = <&ltdc_pins_a>;
 	pinctrl-names = "default";
 	status = "okay";
+	st,fb-bpp = <8>;
 
 	port {
 		ltdc_out_rgb: endpoint {
-- 
2.32.0