Re: [PATCH v12 2/4] Input: add core support for Goodix Berlin Touchscreen IC

[Neil Armstrong <neil.armstrong@linaro.org>]

Hi Dmitry,

On 10/12/2023 07:53, Dmitry Torokhov wrote:
> Hi Neil,
> 
> On Sat, Dec 09, 2023 at 08:33:40AM +0100, Neil Armstrong wrote:
>> Add initial support for the new Goodix "Berlin" touchscreen ICs.
>>
>> 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.
>>
>> [1] https://github.com/goodix/goodix_ts_berlin
>> [2] https://git.codelinaro.org/clo/la/platform/vendor/opensource/touch-drivers
>>
>> Reviewed-by: Jeff LaBundy <jeff@labundy.com>
>> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
> 
> Thank you for resending the patch. I think there is an issue in how you
> read and parse the data in case of more than 2 fingers. It looks like in
> that case you are overwriting the checksum form the first 2 and then not
> reading the new checksum but use some garbage past the touch data. I
> might be mistaken though...

I carefully inspected the code again, and it's correct, otherwise I would have experimented
checksum errors, which isn't the case.

First read from goodix_berlin_irq() is GOODIX_BERLIN_IRQ_READ_LEN(2) length in memory:

[GOODIX_BERLIN_IRQ_EVENT_HEAD_LEN][GOODIX_BERLIN_COOR_DATA_CHECKSUM_SIZE][GOODIX_BERLIN_BYTES_PER_POINT * x]

the pre_buf_len goodix_berlin_touch_handler() get is GOODIX_BERLIN_IRQ_READ_LEN(2), the we complete the
read after the first read, but since the touch checksum is before the touch data, it works because
we complete the data.

I added some comments to clarify the memory layout and re-ordered the items
in the GOODIX_BERLIN_IRQ_READ_LEN() macro to show GOODIX_BERLIN_COOR_DATA_CHECKSUM
is before the GOODIX_BERLIN_BYTES_PER_POINT data.

> 
> I also believe you are leaking afe_data in case of success. We have the
> newfangled __free(kfree) from cleanup.h that should help there.

Indeed it was leaking.

> 
> Another request - we should not have anything in goodix_berlin.h that is
> not used by the I2C and SPI sub-drivers, so the only thing it should
> contain is goodix_berlin_probe() declaration and dev_pm_ops. All other
> defines and definitions should go to goodix_berlin_core.h.
> 
> I made a few more cosmetic changes in the attached patch, please
> consider applying it.
> 
> Thanks.

Thanks,
Neil