dt-bindings: input: Goodix SPI HID Touchscreen

The Goodix GT7986U touch controller report touch data according to the
HID protocol through the SPI bus. However, it is incompatible with
Microsoft's HID-over-SPI protocol.

Signed-off-by: Charles Wang <charles.goodix@gmail.com>
---
 .../bindings/input/goodix,gt7986u.yaml        | 71 +++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/goodix,gt7986u.yaml

On 25/10/2024 18:19, Doug Anderson wrote:
> Hi,
> 
> On Fri, Oct 25, 2024 at 8:59 AM Rob Herring <robh@kernel.org> wrote:
>>
>> On Fri, Oct 25, 2024 at 10:29 AM Doug Anderson <dianders@chromium.org> wrote:
>>>
>>> Charles,
>>>
>>> On Fri, Oct 25, 2024 at 5:03 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>>>>
>>>>> +properties:
>>>>> +  compatible:
>>>>> +    enum:
>>>>> +      - goodix,gt7986u-spi
>>>>
>>>> Compatible is already documented and nothing here explains why we should
>>>> spi variant.
>>>>
>>>>> +
>>>>> +  reg:
>>>>> +    maxItems: 1
>>>>> +
>>>>> +  interrupts:
>>>>> +    maxItems: 1
>>>>> +
>>>>> +  reset-gpios:
>>>>> +    maxItems: 1
>>>>> +
>>>>> +  goodix,hid-report-addr:
>>>>
>>>> I do not see this patch addressing previous review. Sending something
>>>> like this as v1 after long discussions also does not help.
>>>
>>> Krzysztof is right that it's better to wait until we get consensus on
>>> the previous discussion before sending a new patch. I know you were
>>> just trying to help move things forward, but because of the way the
>>> email workflow works, sending a new version tends to fork the
>>> discussion into two threads and adds confusion.
>>>
>>> I know Krzysztof and Rob have been silent during our recent
>>> discussion, but it's also a long discussion. I've been assuming that
>>> they will take some time to digest and reply in a little bit. If they
>>> didn't, IMO it would have been reasonable to explicitly ask them for
>>> feedback in the other thread after giving a bit of time.
>>
>> If the firmware creates fundamentally different interfaces, then
>> different compatibles makes sense. If the same driver handles both bus
>> interfaces, then 1 compatible should be fine. The addition of '-spi'
>> to the compatible doesn't give any indication of a different
>> programming model. I wouldn't care except for folks who will see it
>> and just copy it when their only difference is the bus interface and
>> we get to have the same discussion all over again. So if appending
>> '-spi' is the only thing you can come up with, make it abundantly
>> clear so that others don't blindly copy it. The commit msg is useful
>> for convincing us, but not for that purpose.
> 
> OK, makes sense. Charles: Can you think of any better description for
> this interface than "goodix,gt7986u-spi"? I suppose you could make it
> super obvious that it's running different firmware with
> "goodix,gt7986u-spifw" and maybe that would be a little better.
> 
> I think what Rob is asking for to make it super obvious is that in the
> "description" of the binding you mention that in this case we're
> running a substantially different firmware than GT7986U touchscreens
> represented by the "goodix,gt7986u" binding and thus is considered a
> distinct device.
> 
> At this point, IMO you could wait until Monday in case Krzysztof wants
> to add his $0.02 worth and then you could send a "v2" patch addressing
> the comments so far, though of course you could continue to reply to
> this thread if you have further questions / comments.

And to re-iterate: both commit msg and hardware description in the
binding must clearly explain this why another compatible was chosen for
the same device.

Best regards,
Krzysztof

Hi Doug,

On Fri, Oct 25, 2024 at 08:29:13AM -0700, Doug Anderson wrote:
> Charles,
> 
> On Fri, Oct 25, 2024 at 5:03 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> >
> > > +properties:
> > > +  compatible:
> > > +    enum:
> > > +      - goodix,gt7986u-spi
> >
> > Compatible is already documented and nothing here explains why we should
> > spi variant.
> >
> > > +
> > > +  reg:
> > > +    maxItems: 1
> > > +
> > > +  interrupts:
> > > +    maxItems: 1
> > > +
> > > +  reset-gpios:
> > > +    maxItems: 1
> > > +
> > > +  goodix,hid-report-addr:
> >
> > I do not see this patch addressing previous review. Sending something
> > like this as v1 after long discussions also does not help.
> 
> Krzysztof is right that it's better to wait until we get consensus on
> the previous discussion before sending a new patch. I know you were
> just trying to help move things forward, but because of the way the
> email workflow works, sending a new version tends to fork the
> discussion into two threads and adds confusion.
> 
> I know Krzysztof and Rob have been silent during our recent
> discussion, but it's also a long discussion. I've been assuming that
> they will take some time to digest and reply in a little bit. If they
> didn't, IMO it would have been reasonable to explicitly ask them for
> feedback in the other thread after giving a bit of time.
> 
> As Krzysztof mentioned, if/when you send the "goodix,gt7986u-spi"
> bindings again you'd want to:
> 
> * Make sure it's marked as v2.
> 
> * Make sure any previous review feedback has been addressed. For
> instance, I think Krzysztof requested that you _remove_ the
> goodix,hid-report-addr from the bindings and hardcode this into the
> driver because every GT7986U will have the same hid-report-addr. I
> know that kinda got lost in the discussion but it still needs to be
> addressed or at least responded to. I guess there was at least one
> other comment about "additionalProperties" that you should look for
> and address.
> 
> * Make sure there's some type of version history after-the-cut. Tools
> like "patman" and "b4" can help with this.
> 
> * The commit message should proactively address concerns that came up
> during the review process. In this case if we go with
> "goodix,gt7986u-spi" the commit message would want to say something
> explaining _why_ the "-spi" suffix is appropriate here even though
> normally it wouldn't be. That will help anyone digging through
> history.
> 

I apologize for any confusion caused. As a newcomer, I am still learning
about the community practices.

Thank you very much for your patience and clear explanation. I will recheck
the previous review feedback and provide a new patch marked as v2.

Best regards,
Charles

On Fri, Oct 25, 2024 at 09:19:14AM -0700, Doug Anderson wrote:
> Hi,
> 
> On Fri, Oct 25, 2024 at 8:59 AM Rob Herring <robh@kernel.org> wrote:
> >
> > On Fri, Oct 25, 2024 at 10:29 AM Doug Anderson <dianders@chromium.org> wrote:
> > >
> > > Charles,
> > >
> > > On Fri, Oct 25, 2024 at 5:03 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> > > >
> > > > > +properties:
> > > > > +  compatible:
> > > > > +    enum:
> > > > > +      - goodix,gt7986u-spi
> > > >
> > > > Compatible is already documented and nothing here explains why we should
> > > > spi variant.
> > > >
> > > > > +
> > > > > +  reg:
> > > > > +    maxItems: 1
> > > > > +
> > > > > +  interrupts:
> > > > > +    maxItems: 1
> > > > > +
> > > > > +  reset-gpios:
> > > > > +    maxItems: 1
> > > > > +
> > > > > +  goodix,hid-report-addr:
> > > >
> > > > I do not see this patch addressing previous review. Sending something
> > > > like this as v1 after long discussions also does not help.
> > >
> > > Krzysztof is right that it's better to wait until we get consensus on
> > > the previous discussion before sending a new patch. I know you were
> > > just trying to help move things forward, but because of the way the
> > > email workflow works, sending a new version tends to fork the
> > > discussion into two threads and adds confusion.
> > >
> > > I know Krzysztof and Rob have been silent during our recent
> > > discussion, but it's also a long discussion. I've been assuming that
> > > they will take some time to digest and reply in a little bit. If they
> > > didn't, IMO it would have been reasonable to explicitly ask them for
> > > feedback in the other thread after giving a bit of time.
> >
> > If the firmware creates fundamentally different interfaces, then
> > different compatibles makes sense. If the same driver handles both bus
> > interfaces, then 1 compatible should be fine. The addition of '-spi'
> > to the compatible doesn't give any indication of a different
> > programming model. I wouldn't care except for folks who will see it
> > and just copy it when their only difference is the bus interface and
> > we get to have the same discussion all over again. So if appending
> > '-spi' is the only thing you can come up with, make it abundantly
> > clear so that others don't blindly copy it. The commit msg is useful
> > for convincing us, but not for that purpose.
> 
> OK, makes sense. Charles: Can you think of any better description for
> this interface than "goodix,gt7986u-spi"? I suppose you could make it
> super obvious that it's running different firmware with
> "goodix,gt7986u-spifw" and maybe that would be a little better.
> 
> I think what Rob is asking for to make it super obvious is that in the
> "description" of the binding you mention that in this case we're
> running a substantially different firmware than GT7986U touchscreens
> represented by the "goodix,gt7986u" binding and thus is considered a
> distinct device.
> 
> At this point, IMO you could wait until Monday in case Krzysztof wants
> to add his $0.02 worth and then you could send a "v2" patch addressing
> the comments so far, though of course you could continue to reply to
> this thread if you have further questions / comments.
> 

Thank you for your explanation, I understand your point. I want to clarify
that the gt7986u-spi and gt7986u indeed use two entirely different drivers
and two distinct firmware.

Using "goodix,gt7986u-spi" could indeed cause confusion. How about modifying
it to "goodix,gt7986u-losto" by adding a special code?

Additionally, I would like to confirm: when submitting the v2 patch, should
it be based on this thread or the previous discussion thread?

Best regards,
Charles

Hi,

On Fri, Oct 25, 2024 at 02:03:11PM +0200, Krzysztof Kozlowski wrote:
> On Fri, Oct 25, 2024 at 07:46:43PM +0800, Charles Wang wrote:
> > The Goodix GT7986U touch controller report touch data according to the
> > HID protocol through the SPI bus. However, it is incompatible with
> > Microsoft's HID-over-SPI protocol.
> > 
> > Signed-off-by: Charles Wang <charles.goodix@gmail.com>
> > ---
> >  .../bindings/input/goodix,gt7986u.yaml        | 71 +++++++++++++++++++
> >  1 file changed, 71 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/input/goodix,gt7986u.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/input/goodix,gt7986u.yaml b/Documentation/devicetree/bindings/input/goodix,gt7986u.yaml
> > new file mode 100644
> > index 000000000..849117639
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/input/goodix,gt7986u.yaml
> > @@ -0,0 +1,71 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/input/goodix,gt7986u.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: GOODIX GT7986U SPI HID Touchscreen
> 
> GOODIX or Goodix?

Thank you for catching this, the name should be Goodix.

>
> > +
> > +maintainers:
> > +  - Charles Wang <charles.goodix@gmail.com>
> > +
> > +description: Supports the Goodix GT7986U touchscreen.
> > +  This touch controller reports data packaged according to the HID protocol,
> > +  but is incompatible with Microsoft's HID-over-SPI protocol.
> > +
> > +allOf:
> > +  - $ref: /schemas/spi/spi-peripheral-props.yaml#
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - goodix,gt7986u-spi
> 
> Compatible is already documented and nothing here explains why we should
> spi variant.
> 

Ack. I will modify the compatible name based on our discussion and include an
appropriate description.

>
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  interrupts:
> > +    maxItems: 1
> > +
> > +  reset-gpios:
> > +    maxItems: 1
> > +
> > +  goodix,hid-report-addr:
> 
> I do not see this patch addressing previous review. Sending something
> like this as v1 after long discussions also does not help.
> 
> No, you keep sending the same and the same, without improvements.
>

I apologize for overlooking the discussions regarding this issue.

I would like to clarify that while the current boards use the same address,
but newly designed boards in the future may require different addresses.

Retaining this property would likely offer more flexibility.

>
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description:
> > +      The register address for retrieving HID report data.
> > +      This address is related to the device firmware and may
> > +      change after a firmware update.
> > +
> > +  spi-max-frequency: true
> > +
> > +additionalProperties: false
> 
> Wasn't there a comment about this as well? This goes after required:
> block.
>

Ack, will change to unevaluatedProperties in the next version.

Best regards,
Charles