[PATCH 1/4] dt-bindings: display: bridge: tc358867: Document DPI output support

[PATCH 1/4] dt-bindings: display: bridge: tc358867: Document DPI output support

[Marek Vasut]

The TC358767/TC358867/TC9595 are all capable of operating in multiple
modes, DPI-to-(e)DP, DSI-to-(e)DP, DSI-to-DPI. Document support for the
DPI output port, which can now be connected both as input and output.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Andrzej Hajda <a.hajda@samsung.com>
Cc: Jernej Skrabec <jernej.skrabec@siol.net>
Cc: Jonas Karlman <jonas@kwiboo.se>
Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
Cc: Neil Armstrong <narmstrong@baylibre.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: devicetree@vger.kernel.org
To: dri-devel@lists.freedesktop.org
---
 .../devicetree/bindings/display/bridge/toshiba,tc358767.yaml  | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
index f1541cc05297..5cfda6f2ba69 100644
--- a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
+++ b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
@@ -61,8 +61,8 @@ properties:
       port@1:
         $ref: /schemas/graph.yaml#/properties/port
         description: |
-            DPI input port. The remote endpoint phandle should be a
-            reference to a valid DPI output endpoint node
+            DPI input/output port. The remote endpoint phandle should be a
+            reference to a valid DPI output or input endpoint node.
 
       port@2:
         $ref: /schemas/graph.yaml#/properties/port
-- 
2.33.0

Re: [PATCH 1/4] dt-bindings: display: bridge: tc358867: Document DPI output support

[Laurent Pinchart]

Hi Marek,

Thank you for the patch.

On Sat, Nov 27, 2021 at 04:24:02AM +0100, Marek Vasut wrote:
> The TC358767/TC358867/TC9595 are all capable of operating in multiple
> modes, DPI-to-(e)DP, DSI-to-(e)DP, DSI-to-DPI. Document support for the
> DPI output port, which can now be connected both as input and output.
> 
> Signed-off-by: Marek Vasut <marex@denx.de>
> Cc: Andrzej Hajda <a.hajda@samsung.com>
> Cc: Jernej Skrabec <jernej.skrabec@siol.net>
> Cc: Jonas Karlman <jonas@kwiboo.se>
> Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
> Cc: Neil Armstrong <narmstrong@baylibre.com>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Sam Ravnborg <sam@ravnborg.org>
> Cc: devicetree@vger.kernel.org
> To: dri-devel@lists.freedesktop.org
> ---
>  .../devicetree/bindings/display/bridge/toshiba,tc358767.yaml  | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
> index f1541cc05297..5cfda6f2ba69 100644
> --- a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
> +++ b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
> @@ -61,8 +61,8 @@ properties:
>        port@1:
>          $ref: /schemas/graph.yaml#/properties/port
>          description: |
> -            DPI input port. The remote endpoint phandle should be a
> -            reference to a valid DPI output endpoint node
> +            DPI input/output port. The remote endpoint phandle should be a
> +            reference to a valid DPI output or input endpoint node.

I assume the mode of operation (input or output) will be fixed for a
given hardware design. Isn't this something that should be recorded in
DT ? It would simplify configuration of the device in the driver.

>  
>        port@2:
>          $ref: /schemas/graph.yaml#/properties/port
> 

-- 
Regards,

Laurent Pinchart

Re: [PATCH 1/4] dt-bindings: display: bridge: tc358867: Document DPI output support

[Marek Vasut]

On 12/7/21 17:43, Laurent Pinchart wrote:

[...]

>> diff --git a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
>> index f1541cc05297..5cfda6f2ba69 100644
>> --- a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
>> +++ b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
>> @@ -61,8 +61,8 @@ properties:
>>         port@1:
>>           $ref: /schemas/graph.yaml#/properties/port
>>           description: |
>> -            DPI input port. The remote endpoint phandle should be a
>> -            reference to a valid DPI output endpoint node
>> +            DPI input/output port. The remote endpoint phandle should be a
>> +            reference to a valid DPI output or input endpoint node.
> 
> I assume the mode of operation (input or output) will be fixed for a
> given hardware design. Isn't this something that should be recorded in
> DT ? It would simplify configuration of the device in the driver.

Currently the configuration (DSI-to-DPI / DPI-to-eDP) is inferred from 
the presence of DPI panel. If DPI panel present, DSI-to-DPI, else, 
DPI-to-eDP.

Re: [PATCH 1/4] dt-bindings: display: bridge: tc358867: Document DPI output support

[Laurent Pinchart]

On Tue, Dec 07, 2021 at 05:47:29PM +0100, Marek Vasut wrote:
> On 12/7/21 17:43, Laurent Pinchart wrote:
> 
> [...]
> 
> >> diff --git a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
> >> index f1541cc05297..5cfda6f2ba69 100644
> >> --- a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
> >> +++ b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
> >> @@ -61,8 +61,8 @@ properties:
> >>         port@1:
> >>           $ref: /schemas/graph.yaml#/properties/port
> >>           description: |
> >> -            DPI input port. The remote endpoint phandle should be a
> >> -            reference to a valid DPI output endpoint node
> >> +            DPI input/output port. The remote endpoint phandle should be a
> >> +            reference to a valid DPI output or input endpoint node.
> > 
> > I assume the mode of operation (input or output) will be fixed for a
> > given hardware design. Isn't this something that should be recorded in
> > DT ? It would simplify configuration of the device in the driver.
> 
> Currently the configuration (DSI-to-DPI / DPI-to-eDP) is inferred from 
> the presence of DPI panel. If DPI panel present, DSI-to-DPI, else, 
> DPI-to-eDP.

I've had a look at the driver side, and it seems to complicate things
quite a bit. It seems that specifying the mode of operation explicitly
in DT could make software implementations quite a bit simpler.

-- 
Regards,

Laurent Pinchart

Re: [PATCH 1/4] dt-bindings: display: bridge: tc358867: Document DPI output support

[Marek Vasut]

On 12/7/21 18:03, Laurent Pinchart wrote:
> On Tue, Dec 07, 2021 at 05:47:29PM +0100, Marek Vasut wrote:
>> On 12/7/21 17:43, Laurent Pinchart wrote:
>>
>> [...]
>>
>>>> diff --git a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
>>>> index f1541cc05297..5cfda6f2ba69 100644
>>>> --- a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
>>>> +++ b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
>>>> @@ -61,8 +61,8 @@ properties:
>>>>          port@1:
>>>>            $ref: /schemas/graph.yaml#/properties/port
>>>>            description: |
>>>> -            DPI input port. The remote endpoint phandle should be a
>>>> -            reference to a valid DPI output endpoint node
>>>> +            DPI input/output port. The remote endpoint phandle should be a
>>>> +            reference to a valid DPI output or input endpoint node.
>>>
>>> I assume the mode of operation (input or output) will be fixed for a
>>> given hardware design. Isn't this something that should be recorded in
>>> DT ? It would simplify configuration of the device in the driver.
>>
>> Currently the configuration (DSI-to-DPI / DPI-to-eDP) is inferred from
>> the presence of DPI panel. If DPI panel present, DSI-to-DPI, else,
>> DPI-to-eDP.
> 
> I've had a look at the driver side, and it seems to complicate things
> quite a bit. It seems that specifying the mode of operation explicitly
> in DT could make software implementations quite a bit simpler.

Do you have any specific suggestion ? I explored multiple options while 
writing that DSI-to-DPI driver code, this one was the simplest and least 
redundant one.

Re: [PATCH 1/4] dt-bindings: display: bridge: tc358867: Document DPI output support

[Maxime Ripard]

[-- Attachment #1: Type: text/plain, Size: 2019 bytes --]

On Tue, Dec 07, 2021 at 06:32:38PM +0100, Marek Vasut wrote:
> On 12/7/21 18:03, Laurent Pinchart wrote:
> > On Tue, Dec 07, 2021 at 05:47:29PM +0100, Marek Vasut wrote:
> > > On 12/7/21 17:43, Laurent Pinchart wrote:
> > > 
> > > [...]
> > > 
> > > > > diff --git a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
> > > > > index f1541cc05297..5cfda6f2ba69 100644
> > > > > --- a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
> > > > > +++ b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
> > > > > @@ -61,8 +61,8 @@ properties:
> > > > >          port@1:
> > > > >            $ref: /schemas/graph.yaml#/properties/port
> > > > >            description: |
> > > > > -            DPI input port. The remote endpoint phandle should be a
> > > > > -            reference to a valid DPI output endpoint node
> > > > > +            DPI input/output port. The remote endpoint phandle should be a
> > > > > +            reference to a valid DPI output or input endpoint node.
> > > > 
> > > > I assume the mode of operation (input or output) will be fixed for a
> > > > given hardware design. Isn't this something that should be recorded in
> > > > DT ? It would simplify configuration of the device in the driver.
> > > 
> > > Currently the configuration (DSI-to-DPI / DPI-to-eDP) is inferred from
> > > the presence of DPI panel. If DPI panel present, DSI-to-DPI, else,
> > > DPI-to-eDP.
> > 
> > I've had a look at the driver side, and it seems to complicate things
> > quite a bit. It seems that specifying the mode of operation explicitly
> > in DT could make software implementations quite a bit simpler.
> 
> Do you have any specific suggestion ? I explored multiple options while
> writing that DSI-to-DPI driver code, this one was the simplest and least
> redundant one.

Can we leverage the bus-type property of endpoints?

Maxime

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Re: [PATCH 1/4] dt-bindings: display: bridge: tc358867: Document DPI output support

[Marek Vasut]

On 2/3/22 13:23, Maxime Ripard wrote:
> On Tue, Dec 07, 2021 at 06:32:38PM +0100, Marek Vasut wrote:
>> On 12/7/21 18:03, Laurent Pinchart wrote:
>>> On Tue, Dec 07, 2021 at 05:47:29PM +0100, Marek Vasut wrote:
>>>> On 12/7/21 17:43, Laurent Pinchart wrote:
>>>>
>>>> [...]
>>>>
>>>>>> diff --git a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
>>>>>> index f1541cc05297..5cfda6f2ba69 100644
>>>>>> --- a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
>>>>>> +++ b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml
>>>>>> @@ -61,8 +61,8 @@ properties:
>>>>>>           port@1:
>>>>>>             $ref: /schemas/graph.yaml#/properties/port
>>>>>>             description: |
>>>>>> -            DPI input port. The remote endpoint phandle should be a
>>>>>> -            reference to a valid DPI output endpoint node
>>>>>> +            DPI input/output port. The remote endpoint phandle should be a
>>>>>> +            reference to a valid DPI output or input endpoint node.
>>>>>
>>>>> I assume the mode of operation (input or output) will be fixed for a
>>>>> given hardware design. Isn't this something that should be recorded in
>>>>> DT ? It would simplify configuration of the device in the driver.
>>>>
>>>> Currently the configuration (DSI-to-DPI / DPI-to-eDP) is inferred from
>>>> the presence of DPI panel. If DPI panel present, DSI-to-DPI, else,
>>>> DPI-to-eDP.
>>>
>>> I've had a look at the driver side, and it seems to complicate things
>>> quite a bit. It seems that specifying the mode of operation explicitly
>>> in DT could make software implementations quite a bit simpler.
>>
>> Do you have any specific suggestion ? I explored multiple options while
>> writing that DSI-to-DPI driver code, this one was the simplest and least
>> redundant one.
> 
> Can we leverage the bus-type property of endpoints?

We could, but should we really add a property only for the sake of 
adding a property ? The driver can figure out whether this endpoint is 
DSI-input or DSI-output without such a new property.

Now that I look at the datasheet, the logic can be even simpler:

- If port@0 not connected
   scanout -> port@1 (DPI input) -> port@2 (eDP output) -> panel

- If port@1 not connected
   scanout -> port@0 (DSI input) -> port@2 (eDP output) -> panel

- If port@2 not connected
   scanout -> port@0 (DSI input) -> port@1 (DPI output) -> panel

So with this kind of test in the driver, the driver can determine how 
the TC bridge is wired, without any extra props.