Hi Krzysztof,
On Tue, May 26, 2026 at 08:10:43AM +0200, Krzysztof Kozlowski wrote:
> On 26/05/2026 08:08, Krzysztof Kozlowski wrote:
> > On Tue, May 19, 2026 at 02:42:28PM +0000, Laurentiu Palcu wrote:
> >> From: Sandor Yu <[email protected]>
> >>
> >> Add bindings for Cadence MHDP8501 DisplayPort/HDMI bridge.
> >>
> >> Signed-off-by: Sandor Yu <[email protected]>
> >> Signed-off-by: Laurentiu Palcu <[email protected]>
> >> ---
> >> .../bindings/display/bridge/cdns,mhdp8501.yaml | 136
> >> +++++++++++++++++++++
> >> 1 file changed, 136 insertions(+)
> >>
> >> diff --git
> >> a/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8501.yaml
> >> b/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8501.yaml
> >> new file mode 100644
> >> index 0000000000000..57e7e95199777
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/display/bridge/cdns,mhdp8501.yaml
>
> Filename must match compatible.
>
> >> @@ -0,0 +1,136 @@
> >> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> >> +%YAML 1.2
> >> +---
> >> +$id: http://devicetree.org/schemas/display/bridge/cdns,mhdp8501.yaml#
> >> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >> +
> >> +title: Cadence MHDP8501 DP/HDMI bridge
> >> +
> >> +maintainers:
> >> + - Laurentiu Palcu <[email protected]>
> >> +
> >> +description:
> >> + Cadence MHDP8501 DisplayPort/HDMI interface.
> >> +
> >> +properties:
> >> + compatible:
> >> + enum:
> >> + - fsl,imx8mq-mhdp8501-hdmi
> >> + - fsl,imx8mq-mhdp8501-dp
> >
> > We are at v23 and you will be getting the same questions till you
> > finally fix that commit msg.
> >
> > Why bus/connector is part of the compatible? Device is exactly the same.
> > Please read writing bindings - it covers exactly this case.
The device is the same but, based on the FW, it can act as DP or HDMI
controller. For 8MQ, the FW is loaded by the ROM. I did look at the writing
bindings doc and I assume you're referring to this exact paragraph:
- DON'T use bus suffixes to encode the type of interface device is using.
The parent bus node already implies that interface. DON'T add the type of
device, if the device cannot be anything else.
I don't see how is this applicable in this particular case. The parent bus node
does not imply the interface and, as I explained previously, the device can be
either DP or HDMI.
>
> And this was BTW completely different in previous version.
It was indeed. However, the problem is that there's no way to detect
from the controller's registers if we're in DP mode or HDMI. In v22 I
added a DT traversal function to detect the connector type from the last
node but it was suggested to me that having 2 compatibles would be a
much cleaner solution and I agree.
--
Thanks,
Laurentiu
