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Message-ID: <1a7bdcc1-c737-83c4-24af-eb0028ed45f4@redhat.com>
Date:   Tue, 6 Jun 2023 20:55:59 +0200
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Subject: Re: [PATCH RFC 0/4] input: touchscreen: add initial support for
 Goodix Berlin touchscreen IC
To:     neil.armstrong@linaro.org,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Bastien Nocera <hadess@hadess.net>,
        Henrik Rydberg <rydberg@bitmath.org>
Cc:     linux-input@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20230606-topic-goodix-berlin-upstream-initial-v1-0-4a0741b8aefd@linaro.org>
 <f5f20de8-851a-fe20-4664-62b6de14ebd7@redhat.com>
 <2677ae8c-59d3-b658-dc3f-918838ac0fb6@linaro.org>
Content-Language: en-US
From:   Hans de Goede <hdegoede@redhat.com>
In-Reply-To: <2677ae8c-59d3-b658-dc3f-918838ac0fb6@linaro.org>
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Precedence: bulk

Hi,

On 6/6/23 20:12, Neil Armstrong wrote:
> Hi,
> 
> On 06/06/2023 17:31, Hans de Goede wrote:
>> Hi Neil,
>>
>> On 6/6/23 16:31, Neil Armstrong wrote:
>>> These touchscreen ICs support SPI, I2C and I3C interface, up to
>>> 10 finger touch, stylus and gestures events.
>>>
>>> This initial driver is derived from the Goodix goodix_ts_berlin
>>> available at [1] and [2] and only supports the GT9916 IC
>>> present on the Qualcomm SM8550 MTP & QRD touch panel.
>>>
>>> The current implementation only supports BerlinD, aka GT9916.
>>>
>>> Support for advanced features like:
>>> - Firmware & config update
>>> - Stylus events
>>> - Gestures events
>>> - Previous revisions support (BerlinA or BerlinB)
>>> is not included in current version.
>>>
>>> The current support will work with currently flashed firmware
>>> and config, and bail out if firmware or config aren't flashed yet.
>>
>> What I'm missing here / in the commit msg of
>> "input: touchscreen: add core support for Goodix Berlin Touchscreen IC"
>>
>> is an explanation why this is a new driver instead of adding
>> support to the existing goodix.c code.
>>
>> I assume you have good reasons for this, but it would be good
>> if you can write the reasons for this down.
> 
> Sure, should I write it down here and/or update the commit message in a new revision ?

Yes please add this to the commit msg for the next version.

> Anyway, here's the reasons:
> - globally the event handling "looks like" the current goodix.c, but again the offsets
> are again different and none of the register address are the same, and unlike the current
> support all registers are provided by the "ic_info" structure
> - while with the current code it *could* be possible to merge it, with a lot of changes,
> the firmware management looks really different, and it would be really hard to merge.
> 
> But I may be wrong, and may be misleaded by the goodix driver structure (even if it
> went through a really heavy cleaning process).

No doing a new separate driver sounds about right to me. The current goodix driver already has a lot of different code-paths. So since there does not seem to be a whole lot of code sharing potential adding yet more special case handling / paths is not desirable IMHO.

Regards,

Hans


>>> [1] https://github.com/goodix/goodix_ts_berlin
>>> [2] https://git.codelinaro.org/clo/la/platform/vendor/opensource/touch-drivers
>>>
>>> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
>>> ---
>>> Neil Armstrong (4):
>>>        dt-bindings: input: document Goodix Berlin Touchscreen IC
>>>        input: touchscreen: add core support for Goodix Berlin Touchscreen IC
>>>        input: touchscreen: add I2C support for Goodix Berlin Touchscreen IC
>>>        input: touchscreen: add SPI support for Goodix Berlin Touchscreen IC
>>>
>>>   .../bindings/input/touchscreen/goodix-berlin.yaml  |  81 ++
>>>   drivers/input/touchscreen/Kconfig                  |  33 +
>>>   drivers/input/touchscreen/Makefile                 |   3 +
>>>   drivers/input/touchscreen/goodix_berlin.h          | 228 +++++
>>>   drivers/input/touchscreen/goodix_berlin_core.c     | 935 +++++++++++++++++++++
>>>   drivers/input/touchscreen/goodix_berlin_i2c.c      |  76 ++
>>>   drivers/input/touchscreen/goodix_berlin_spi.c      | 183 ++++
>>>   7 files changed, 1539 insertions(+)
>>> ---
>>> base-commit: 6db29e14f4fb7bce9eb5290288e71b05c2b0d118
>>> change-id: 20230606-topic-goodix-berlin-upstream-initial-ba97e8ec8f4c
>>>
>>> Best regards,
>>
>