diff mbox series

[v2,1/3] dt-bindings: display: st7701: Add Anbernic RG28XX panel

Message ID 20240628051019.975172-2-kikuchan98@gmail.com (mailing list archive)
State New, archived
Headers show
Series drm/panel: st7701: Add Anbernic RG28XX panel support | expand

Commit Message

Hironori KIKUCHI June 28, 2024, 5:10 a.m. UTC
The RG28XX panel is a display panel of the Anbernic RG28XX, a handheld
gaming device from Anbernic. It is 2.8 inches in size (diagonally) with
a resolution of 480x640.

This panel is driven by a variant of the ST7701 driver IC internally,
confirmed by dumping and analyzing its BSP initialization sequence
by using a logic analyzer. It is very similar to the existing
densitron,dmt028vghmcmi-1a panel, but differs in some unknown
register values, so add a new entry for the panel to distinguish them.

Additionally, the panel is connected via SPI instead of MIPI DSI.
So add and modify for SPI as well.

Signed-off-by: Hironori KIKUCHI <kikuchan98@gmail.com>
---
 .../display/panel/sitronix,st7701.yaml        | 69 +++++++++++++++++--
 1 file changed, 64 insertions(+), 5 deletions(-)

Comments

Conor Dooley June 28, 2024, 4:27 p.m. UTC | #1
On Fri, Jun 28, 2024 at 02:10:15PM +0900, Hironori KIKUCHI wrote:
> The RG28XX panel is a display panel of the Anbernic RG28XX, a handheld
> gaming device from Anbernic. It is 2.8 inches in size (diagonally) with
> a resolution of 480x640.
> 
> This panel is driven by a variant of the ST7701 driver IC internally,
> confirmed by dumping and analyzing its BSP initialization sequence
> by using a logic analyzer. It is very similar to the existing
> densitron,dmt028vghmcmi-1a panel, but differs in some unknown
> register values, so add a new entry for the panel to distinguish them.
> 
> Additionally, the panel is connected via SPI instead of MIPI DSI.
> So add and modify for SPI as well.
> 
> Signed-off-by: Hironori KIKUCHI <kikuchan98@gmail.com>
> ---
>  .../display/panel/sitronix,st7701.yaml        | 69 +++++++++++++++++--
>  1 file changed, 64 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml b/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml
> index b348f5bf0a9..835ea436531 100644
> --- a/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml
> +++ b/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml
> @@ -20,21 +20,19 @@ description: |
>    Densitron DMT028VGHMCMI-1A is 480x640, 2-lane MIPI DSI LCD panel
>    which has built-in ST7701 chip.
>  
> -allOf:
> -  - $ref: panel-common.yaml#
> -
>  properties:
>    compatible:
>      items:
>        - enum:
>            - anbernic,rg-arc-panel
> +          - anbernic,rg28xx-panel

Please no wildcards in compatibles - what is the actual model of this
panel? I don't really want to see the model of the handheld here if
possible.

>            - densitron,dmt028vghmcmi-1a
>            - elida,kd50t048a
>            - techstar,ts8550b
>        - const: sitronix,st7701
>  
>    reg:
> -    description: DSI virtual channel used by that screen
> +    description: DSI / SPI channel used by that screen
>      maxItems: 1
>  
>    VCC-supply:
> @@ -43,6 +41,13 @@ properties:
>    IOVCC-supply:
>      description: I/O system regulator
>  
> +  dc-gpios:
> +    maxItems: 1
> +    description:
> +      Controller data/command selection (D/CX) in 4-line SPI mode.
> +      If not set, the controller is in 3-line SPI mode.
> +      Disallowed for DSI.
> +
>    port: true
>    reset-gpios: true
>    rotation: true
> @@ -57,7 +62,38 @@ required:
>    - port
>    - reset-gpios
>  
> -additionalProperties: false
> +allOf:
> +  - $ref: panel-common.yaml#
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            # SPI connected panels
> +            enum:
> +              - anbernic,rg28xx-panel
> +    then:
> +      $ref: /schemas/spi/spi-peripheral-props.yaml

I'm not really keen on this. I'd rather see a different binding for the
SPI version compared to the MIPI ones. Is doing things like this common
for panels? If it is, I'll turn a blind eye..

> +
> +  - if:
> +      properties:
> +        compatible:
> +          not:
> +            contains:
> +              # DSI or SPI without D/CX pin
> +              enum:
> +                - anbernic,rg-arc-panel
> +                - anbernic,rg28xx-panel
> +                - densitron,dmt028vghmcmi-1a
> +                - elida,kd50t048a
> +                - techstar,ts8550b

This is all the compatibles in the file, so nothing is allowed to use
dc-gpios? Why bother adding it?

Confused,
Conor.

> +    then:
> +      required:
> +        - dc-gpios
> +    else:
> +      properties:
> +        dc-gpios: false
> +
> +unevaluatedProperties: false
>  
>  examples:
>    - |
> @@ -82,3 +118,26 @@ examples:
>              };
>          };
>      };
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +
> +    spi {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        panel@0 {
> +            compatible = "anbernic,rg28xx-panel", "sitronix,st7701";
> +            reg = <0>;
> +            spi-max-frequency = <3125000>;
> +            VCC-supply = <&reg_lcd>;
> +            IOVCC-supply = <&reg_lcd>;
> +            reset-gpios = <&pio 8 14 GPIO_ACTIVE_HIGH>; /* LCD-RST: PI14 */
> +            backlight = <&backlight>;
> +
> +            port {
> +                panel_in_rgb: endpoint {
> +                    remote-endpoint = <&tcon_lcd0_out_lcd>;
> +                };
> +            };
> +        };
> +    };
> -- 
> 2.45.2
>
Hironori KIKUCHI June 29, 2024, 8:26 a.m. UTC | #2
Hello Conor,

Thank you for your reply.

On Sat, Jun 29, 2024 at 1:27 AM Conor Dooley <conor@kernel.org> wrote:
>
> On Fri, Jun 28, 2024 at 02:10:15PM +0900, Hironori KIKUCHI wrote:
> > The RG28XX panel is a display panel of the Anbernic RG28XX, a handheld
> > gaming device from Anbernic. It is 2.8 inches in size (diagonally) with
> > a resolution of 480x640.
> >
> > This panel is driven by a variant of the ST7701 driver IC internally,
> > confirmed by dumping and analyzing its BSP initialization sequence
> > by using a logic analyzer. It is very similar to the existing
> > densitron,dmt028vghmcmi-1a panel, but differs in some unknown
> > register values, so add a new entry for the panel to distinguish them.
> >
> > Additionally, the panel is connected via SPI instead of MIPI DSI.
> > So add and modify for SPI as well.
> >
> > Signed-off-by: Hironori KIKUCHI <kikuchan98@gmail.com>
> > ---
> >  .../display/panel/sitronix,st7701.yaml        | 69 +++++++++++++++++--
> >  1 file changed, 64 insertions(+), 5 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml b/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml
> > index b348f5bf0a9..835ea436531 100644
> > --- a/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml
> > +++ b/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml
> > @@ -20,21 +20,19 @@ description: |
> >    Densitron DMT028VGHMCMI-1A is 480x640, 2-lane MIPI DSI LCD panel
> >    which has built-in ST7701 chip.
> >
> > -allOf:
> > -  - $ref: panel-common.yaml#
> > -
> >  properties:
> >    compatible:
> >      items:
> >        - enum:
> >            - anbernic,rg-arc-panel
> > +          - anbernic,rg28xx-panel
>
> Please no wildcards in compatibles - what is the actual model of this
> panel? I don't really want to see the model of the handheld here if
> possible.

Well, the "RG28XX" is the actual product name of the device...
Besides, there is no vendor name or model name on the panel; there is
no information at all.
Since the panel cannot be disassembled from the housing of the device,
I named it like this.

>
> >            - densitron,dmt028vghmcmi-1a
> >            - elida,kd50t048a
> >            - techstar,ts8550b
> >        - const: sitronix,st7701
> >
> >    reg:
> > -    description: DSI virtual channel used by that screen
> > +    description: DSI / SPI channel used by that screen
> >      maxItems: 1
> >
> >    VCC-supply:
> > @@ -43,6 +41,13 @@ properties:
> >    IOVCC-supply:
> >      description: I/O system regulator
> >
> > +  dc-gpios:
> > +    maxItems: 1
> > +    description:
> > +      Controller data/command selection (D/CX) in 4-line SPI mode.
> > +      If not set, the controller is in 3-line SPI mode.
> > +      Disallowed for DSI.
> > +
> >    port: true
> >    reset-gpios: true
> >    rotation: true
> > @@ -57,7 +62,38 @@ required:
> >    - port
> >    - reset-gpios
> >
> > -additionalProperties: false
> > +allOf:
> > +  - $ref: panel-common.yaml#
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          contains:
> > +            # SPI connected panels
> > +            enum:
> > +              - anbernic,rg28xx-panel
> > +    then:
> > +      $ref: /schemas/spi/spi-peripheral-props.yaml
>
> I'm not really keen on this. I'd rather see a different binding for the
> SPI version compared to the MIPI ones. Is doing things like this common
> for panels? If it is, I'll turn a blind eye..

This might be the first case that a driver supports both DSI and SPI
for a panel.
The panel can be either a DSI device or an SPI device.
I'm not sure if this is the right way to represent it in the documentation...

>
> > +
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          not:
> > +            contains:
> > +              # DSI or SPI without D/CX pin
> > +              enum:
> > +                - anbernic,rg-arc-panel
> > +                - anbernic,rg28xx-panel
> > +                - densitron,dmt028vghmcmi-1a
> > +                - elida,kd50t048a
> > +                - techstar,ts8550b
>
> This is all the compatibles in the file, so nothing is allowed to use
> dc-gpios? Why bother adding it?

There are 3 types of connections that the driver supports: DSI, SPI
with D/CX pin, and SPI without D/CX pin.
Although most SPI panels don't have a D/CX pin, theoretically "SPI
with D/CX pin" exists.
So, it's just prepared for that.

IMHO, once it's found, the list should be negated. List panels for SPI
with D/CX pin, instead.

>
> Confused,
> Conor.
>
> > +    then:
> > +      required:
> > +        - dc-gpios
> > +    else:
> > +      properties:
> > +        dc-gpios: false
> > +
> > +unevaluatedProperties: false
> >
> >  examples:
> >    - |
> > @@ -82,3 +118,26 @@ examples:
> >              };
> >          };
> >      };
> > +  - |
> > +    #include <dt-bindings/gpio/gpio.h>
> > +
> > +    spi {
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +
> > +        panel@0 {
> > +            compatible = "anbernic,rg28xx-panel", "sitronix,st7701";
> > +            reg = <0>;
> > +            spi-max-frequency = <3125000>;
> > +            VCC-supply = <&reg_lcd>;
> > +            IOVCC-supply = <&reg_lcd>;
> > +            reset-gpios = <&pio 8 14 GPIO_ACTIVE_HIGH>; /* LCD-RST: PI14 */
> > +            backlight = <&backlight>;
> > +
> > +            port {
> > +                panel_in_rgb: endpoint {
> > +                    remote-endpoint = <&tcon_lcd0_out_lcd>;
> > +                };
> > +            };
> > +        };
> > +    };
> > --
> > 2.45.2
> >

Best regards,
kikuchan.
Conor Dooley June 30, 2024, 2:17 p.m. UTC | #3
On Sat, Jun 29, 2024 at 05:26:56PM +0900, Hironori KIKUCHI wrote:
> Hello Conor,
> 
> Thank you for your reply.
> 
> On Sat, Jun 29, 2024 at 1:27 AM Conor Dooley <conor@kernel.org> wrote:
> >
> > On Fri, Jun 28, 2024 at 02:10:15PM +0900, Hironori KIKUCHI wrote:
> > > The RG28XX panel is a display panel of the Anbernic RG28XX, a handheld
> > > gaming device from Anbernic. It is 2.8 inches in size (diagonally) with
> > > a resolution of 480x640.
> > >
> > > This panel is driven by a variant of the ST7701 driver IC internally,
> > > confirmed by dumping and analyzing its BSP initialization sequence
> > > by using a logic analyzer. It is very similar to the existing
> > > densitron,dmt028vghmcmi-1a panel, but differs in some unknown
> > > register values, so add a new entry for the panel to distinguish them.
> > >
> > > Additionally, the panel is connected via SPI instead of MIPI DSI.
> > > So add and modify for SPI as well.
> > >
> > > Signed-off-by: Hironori KIKUCHI <kikuchan98@gmail.com>
> > > ---
> > >  .../display/panel/sitronix,st7701.yaml        | 69 +++++++++++++++++--
> > >  1 file changed, 64 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml b/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml
> > > index b348f5bf0a9..835ea436531 100644
> > > --- a/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml
> > > +++ b/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml
> > > @@ -20,21 +20,19 @@ description: |
> > >    Densitron DMT028VGHMCMI-1A is 480x640, 2-lane MIPI DSI LCD panel
> > >    which has built-in ST7701 chip.
> > >
> > > -allOf:
> > > -  - $ref: panel-common.yaml#
> > > -
> > >  properties:
> > >    compatible:
> > >      items:
> > >        - enum:
> > >            - anbernic,rg-arc-panel
> > > +          - anbernic,rg28xx-panel
> >
> > Please no wildcards in compatibles - what is the actual model of this
> > panel? I don't really want to see the model of the handheld here if
> > possible.
> 
> Well, the "RG28XX" is the actual product name of the device...

Ah, I see. I didn't realise that.

> Besides, there is no vendor name or model name on the panel; there is
> no information at all.
> Since the panel cannot be disassembled from the housing of the device,
> I named it like this.
> 
> >
> > >            - densitron,dmt028vghmcmi-1a
> > >            - elida,kd50t048a
> > >            - techstar,ts8550b
> > >        - const: sitronix,st7701
> > >
> > >    reg:
> > > -    description: DSI virtual channel used by that screen
> > > +    description: DSI / SPI channel used by that screen
> > >      maxItems: 1
> > >
> > >    VCC-supply:
> > > @@ -43,6 +41,13 @@ properties:
> > >    IOVCC-supply:
> > >      description: I/O system regulator
> > >
> > > +  dc-gpios:
> > > +    maxItems: 1
> > > +    description:
> > > +      Controller data/command selection (D/CX) in 4-line SPI mode.
> > > +      If not set, the controller is in 3-line SPI mode.
> > > +      Disallowed for DSI.
> > > +
> > >    port: true
> > >    reset-gpios: true
> > >    rotation: true
> > > @@ -57,7 +62,38 @@ required:
> > >    - port
> > >    - reset-gpios
> > >
> > > -additionalProperties: false
> > > +allOf:
> > > +  - $ref: panel-common.yaml#
> > > +  - if:
> > > +      properties:
> > > +        compatible:
> > > +          contains:
> > > +            # SPI connected panels
> > > +            enum:
> > > +              - anbernic,rg28xx-panel
> > > +    then:
> > > +      $ref: /schemas/spi/spi-peripheral-props.yaml
> >
> > I'm not really keen on this. I'd rather see a different binding for the
> > SPI version compared to the MIPI ones. Is doing things like this common
> > for panels? If it is, I'll turn a blind eye..
> 
> This might be the first case that a driver supports both DSI and SPI
> for a panel.
> The panel can be either a DSI device or an SPI device.

The commit message sounded like the panel was capable of doing SPI
instead of DSI, is that not the case and the panel is actually capable
of doing both, just happens to be connected as SPI in this particular
device?

> I'm not sure if this is the right way to represent it in the documentation...
> 
> >
> > > +
> > > +  - if:
> > > +      properties:
> > > +        compatible:
> > > +          not:
> > > +            contains:
> > > +              # DSI or SPI without D/CX pin
> > > +              enum:
> > > +                - anbernic,rg-arc-panel
> > > +                - anbernic,rg28xx-panel
> > > +                - densitron,dmt028vghmcmi-1a
> > > +                - elida,kd50t048a
> > > +                - techstar,ts8550b
> >
> > This is all the compatibles in the file, so nothing is allowed to use
> > dc-gpios? Why bother adding it?
> 
> There are 3 types of connections that the driver supports: DSI, SPI
> with D/CX pin, and SPI without D/CX pin.
> Although most SPI panels don't have a D/CX pin, theoretically "SPI
> with D/CX pin" exists.
> So, it's just prepared for that.
> 
> IMHO, once it's found, the list should be negated. List panels for SPI
> with D/CX pin, instead.

To be honest, I'd just delete this complication until something arrives
that actually uses that pin.

Cheers,
Conor.
Hironori KIKUCHI July 1, 2024, 5:28 p.m. UTC | #4
Hi Conor,

On Sun, Jun 30, 2024 at 11:17 PM Conor Dooley <conor@kernel.org> wrote:
>
> On Sat, Jun 29, 2024 at 05:26:56PM +0900, Hironori KIKUCHI wrote:
> > Hello Conor,
> >
> > Thank you for your reply.
> >
> > On Sat, Jun 29, 2024 at 1:27 AM Conor Dooley <conor@kernel.org> wrote:
> > >
> > > On Fri, Jun 28, 2024 at 02:10:15PM +0900, Hironori KIKUCHI wrote:
> > > > The RG28XX panel is a display panel of the Anbernic RG28XX, a handheld
> > > > gaming device from Anbernic. It is 2.8 inches in size (diagonally) with
> > > > a resolution of 480x640.
> > > >
> > > > This panel is driven by a variant of the ST7701 driver IC internally,
> > > > confirmed by dumping and analyzing its BSP initialization sequence
> > > > by using a logic analyzer. It is very similar to the existing
> > > > densitron,dmt028vghmcmi-1a panel, but differs in some unknown
> > > > register values, so add a new entry for the panel to distinguish them.
> > > >
> > > > Additionally, the panel is connected via SPI instead of MIPI DSI.
> > > > So add and modify for SPI as well.
> > > >
> > > > Signed-off-by: Hironori KIKUCHI <kikuchan98@gmail.com>
> > > > ---
> > > >  .../display/panel/sitronix,st7701.yaml        | 69 +++++++++++++++++--
> > > >  1 file changed, 64 insertions(+), 5 deletions(-)
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml b/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml
> > > > index b348f5bf0a9..835ea436531 100644
> > > > --- a/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml
> > > > +++ b/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml
> > > > @@ -20,21 +20,19 @@ description: |
> > > >    Densitron DMT028VGHMCMI-1A is 480x640, 2-lane MIPI DSI LCD panel
> > > >    which has built-in ST7701 chip.
> > > >
> > > > -allOf:
> > > > -  - $ref: panel-common.yaml#
> > > > -
> > > >  properties:
> > > >    compatible:
> > > >      items:
> > > >        - enum:
> > > >            - anbernic,rg-arc-panel
> > > > +          - anbernic,rg28xx-panel
> > >
> > > Please no wildcards in compatibles - what is the actual model of this
> > > panel? I don't really want to see the model of the handheld here if
> > > possible.
> >
> > Well, the "RG28XX" is the actual product name of the device...
>
> Ah, I see. I didn't realise that.
>
> > Besides, there is no vendor name or model name on the panel; there is
> > no information at all.
> > Since the panel cannot be disassembled from the housing of the device,
> > I named it like this.
> >
> > >
> > > >            - densitron,dmt028vghmcmi-1a
> > > >            - elida,kd50t048a
> > > >            - techstar,ts8550b
> > > >        - const: sitronix,st7701
> > > >
> > > >    reg:
> > > > -    description: DSI virtual channel used by that screen
> > > > +    description: DSI / SPI channel used by that screen
> > > >      maxItems: 1
> > > >
> > > >    VCC-supply:
> > > > @@ -43,6 +41,13 @@ properties:
> > > >    IOVCC-supply:
> > > >      description: I/O system regulator
> > > >
> > > > +  dc-gpios:
> > > > +    maxItems: 1
> > > > +    description:
> > > > +      Controller data/command selection (D/CX) in 4-line SPI mode.
> > > > +      If not set, the controller is in 3-line SPI mode.
> > > > +      Disallowed for DSI.
> > > > +
> > > >    port: true
> > > >    reset-gpios: true
> > > >    rotation: true
> > > > @@ -57,7 +62,38 @@ required:
> > > >    - port
> > > >    - reset-gpios
> > > >
> > > > -additionalProperties: false
> > > > +allOf:
> > > > +  - $ref: panel-common.yaml#
> > > > +  - if:
> > > > +      properties:
> > > > +        compatible:
> > > > +          contains:
> > > > +            # SPI connected panels
> > > > +            enum:
> > > > +              - anbernic,rg28xx-panel
> > > > +    then:
> > > > +      $ref: /schemas/spi/spi-peripheral-props.yaml
> > >
> > > I'm not really keen on this. I'd rather see a different binding for the
> > > SPI version compared to the MIPI ones. Is doing things like this common
> > > for panels? If it is, I'll turn a blind eye..
> >
> > This might be the first case that a driver supports both DSI and SPI
> > for a panel.
> > The panel can be either a DSI device or an SPI device.
>
> The commit message sounded like the panel was capable of doing SPI
> instead of DSI, is that not the case and the panel is actually capable
> of doing both, just happens to be connected as SPI in this particular
> device?

Sorry for the confusion.
I think it depends on what the "panel" refers to...
Although the "panel driver IC" (ST7701 variant) is capable of doing
both, the "panel assy" (including its cable) of the RG28XX only has an
SPI interface in its pinout.
If the compatible string "rg28xx-panel" represents the assy, then I
could say the "panel" only supports SPI, and the other panels only
support DSI.
But if it only represents a specific LCD panel and its driver IC with
control parameters, then it theoretically supports both, and it might
be sufficient to just include spi-peripheral-props, as in v1.
v1: https://lore.kernel.org/linux-kernel/20240618081515.1215552-2-kikuchan98@gmail.com/

>
> > I'm not sure if this is the right way to represent it in the documentation...
> >
> > >
> > > > +
> > > > +  - if:
> > > > +      properties:
> > > > +        compatible:
> > > > +          not:
> > > > +            contains:
> > > > +              # DSI or SPI without D/CX pin
> > > > +              enum:
> > > > +                - anbernic,rg-arc-panel
> > > > +                - anbernic,rg28xx-panel
> > > > +                - densitron,dmt028vghmcmi-1a
> > > > +                - elida,kd50t048a
> > > > +                - techstar,ts8550b
> > >
> > > This is all the compatibles in the file, so nothing is allowed to use
> > > dc-gpios? Why bother adding it?
> >
> > There are 3 types of connections that the driver supports: DSI, SPI
> > with D/CX pin, and SPI without D/CX pin.
> > Although most SPI panels don't have a D/CX pin, theoretically "SPI
> > with D/CX pin" exists.
> > So, it's just prepared for that.
> >
> > IMHO, once it's found, the list should be negated. List panels for SPI
> > with D/CX pin, instead.
>
> To be honest, I'd just delete this complication until something arrives
> that actually uses that pin.
>
> Cheers,
> Conor.

Best regards,
kikuchan.
Conor Dooley July 2, 2024, 3:34 p.m. UTC | #5
On Tue, Jul 02, 2024 at 02:28:27AM +0900, Hironori KIKUCHI wrote:
> On Sun, Jun 30, 2024 at 11:17 PM Conor Dooley <conor@kernel.org> wrote:
> > On Sat, Jun 29, 2024 at 05:26:56PM +0900, Hironori KIKUCHI wrote:
> > > On Sat, Jun 29, 2024 at 1:27 AM Conor Dooley <conor@kernel.org> wrote:
> > > > On Fri, Jun 28, 2024 at 02:10:15PM +0900, Hironori KIKUCHI wrote:

> > > > >            - densitron,dmt028vghmcmi-1a
> > > > >            - elida,kd50t048a
> > > > >            - techstar,ts8550b
> > > > >        - const: sitronix,st7701
> > > > >
> > > > >    reg:
> > > > > -    description: DSI virtual channel used by that screen
> > > > > +    description: DSI / SPI channel used by that screen
> > > > >      maxItems: 1
> > > > >
> > > > >    VCC-supply:
> > > > > @@ -43,6 +41,13 @@ properties:
> > > > >    IOVCC-supply:
> > > > >      description: I/O system regulator
> > > > >
> > > > > +  dc-gpios:
> > > > > +    maxItems: 1
> > > > > +    description:
> > > > > +      Controller data/command selection (D/CX) in 4-line SPI mode.
> > > > > +      If not set, the controller is in 3-line SPI mode.
> > > > > +      Disallowed for DSI.
> > > > > +
> > > > >    port: true
> > > > >    reset-gpios: true
> > > > >    rotation: true
> > > > > @@ -57,7 +62,38 @@ required:
> > > > >    - port
> > > > >    - reset-gpios
> > > > >
> > > > > -additionalProperties: false
> > > > > +allOf:
> > > > > +  - $ref: panel-common.yaml#
> > > > > +  - if:
> > > > > +      properties:
> > > > > +        compatible:
> > > > > +          contains:
> > > > > +            # SPI connected panels
> > > > > +            enum:
> > > > > +              - anbernic,rg28xx-panel
> > > > > +    then:
> > > > > +      $ref: /schemas/spi/spi-peripheral-props.yaml
> > > >
> > > > I'm not really keen on this. I'd rather see a different binding for the
> > > > SPI version compared to the MIPI ones. Is doing things like this common
> > > > for panels? If it is, I'll turn a blind eye..
> > >
> > > This might be the first case that a driver supports both DSI and SPI
> > > for a panel.
> > > The panel can be either a DSI device or an SPI device.
> >
> > The commit message sounded like the panel was capable of doing SPI
> > instead of DSI, is that not the case and the panel is actually capable
> > of doing both, just happens to be connected as SPI in this particular
> > device?
> 
> Sorry for the confusion.
> I think it depends on what the "panel" refers to...
> Although the "panel driver IC" (ST7701 variant) is capable of doing
> both, the "panel assy" (including its cable) of the RG28XX only has an
> SPI interface in its pinout.
> If the compatible string "rg28xx-panel" represents the assy, then I
> could say the "panel" only supports SPI, and the other panels only
> support DSI.
> But if it only represents a specific LCD panel and its driver IC with
> control parameters, then it theoretically supports both, and it might
> be sufficient to just include spi-peripheral-props, as in v1.
> v1: https://lore.kernel.org/linux-kernel/20240618081515.1215552-2-kikuchan98@gmail.com/

I thought about it some more, and I think what you've got for this in
the binding at present is fine. Splitting the binding I think would
require a select and wouldn't really be any "cleaner" of an
implementation.

Thanks,
Conor.
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml b/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml
index b348f5bf0a9..835ea436531 100644
--- a/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml
+++ b/Documentation/devicetree/bindings/display/panel/sitronix,st7701.yaml
@@ -20,21 +20,19 @@  description: |
   Densitron DMT028VGHMCMI-1A is 480x640, 2-lane MIPI DSI LCD panel
   which has built-in ST7701 chip.
 
-allOf:
-  - $ref: panel-common.yaml#
-
 properties:
   compatible:
     items:
       - enum:
           - anbernic,rg-arc-panel
+          - anbernic,rg28xx-panel
           - densitron,dmt028vghmcmi-1a
           - elida,kd50t048a
           - techstar,ts8550b
       - const: sitronix,st7701
 
   reg:
-    description: DSI virtual channel used by that screen
+    description: DSI / SPI channel used by that screen
     maxItems: 1
 
   VCC-supply:
@@ -43,6 +41,13 @@  properties:
   IOVCC-supply:
     description: I/O system regulator
 
+  dc-gpios:
+    maxItems: 1
+    description:
+      Controller data/command selection (D/CX) in 4-line SPI mode.
+      If not set, the controller is in 3-line SPI mode.
+      Disallowed for DSI.
+
   port: true
   reset-gpios: true
   rotation: true
@@ -57,7 +62,38 @@  required:
   - port
   - reset-gpios
 
-additionalProperties: false
+allOf:
+  - $ref: panel-common.yaml#
+  - if:
+      properties:
+        compatible:
+          contains:
+            # SPI connected panels
+            enum:
+              - anbernic,rg28xx-panel
+    then:
+      $ref: /schemas/spi/spi-peripheral-props.yaml
+
+  - if:
+      properties:
+        compatible:
+          not:
+            contains:
+              # DSI or SPI without D/CX pin
+              enum:
+                - anbernic,rg-arc-panel
+                - anbernic,rg28xx-panel
+                - densitron,dmt028vghmcmi-1a
+                - elida,kd50t048a
+                - techstar,ts8550b
+    then:
+      required:
+        - dc-gpios
+    else:
+      properties:
+        dc-gpios: false
+
+unevaluatedProperties: false
 
 examples:
   - |
@@ -82,3 +118,26 @@  examples:
             };
         };
     };
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        panel@0 {
+            compatible = "anbernic,rg28xx-panel", "sitronix,st7701";
+            reg = <0>;
+            spi-max-frequency = <3125000>;
+            VCC-supply = <&reg_lcd>;
+            IOVCC-supply = <&reg_lcd>;
+            reset-gpios = <&pio 8 14 GPIO_ACTIVE_HIGH>; /* LCD-RST: PI14 */
+            backlight = <&backlight>;
+
+            port {
+                panel_in_rgb: endpoint {
+                    remote-endpoint = <&tcon_lcd0_out_lcd>;
+                };
+            };
+        };
+    };