Re: [PATCH 1/2] platform/x86: touchscreen_dmi: Allow partial (prefix) matches for ACPI names

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 2/13/24 02:01, Kuppuswamy Sathyanarayanan wrote:
> 
> On 2/12/24 4:06 AM, Hans de Goede wrote:
>> On some devices the ACPI name of the touchscreen is e.g. either
>> MSSL1680:00 or MSSL1680:01 depending on the BIOS version.
>>
>> This happens for example on the "Chuwi Hi8 Air" tablet where the initial
>> commit's ts_data uses "MSSL1680:00" but the tablets from the github issue
>> and linux-hardware.org probe linked below both use "MSSL1680:01".
>>
>> Replace the strcmp() match on ts_data->acpi_name with a strstarts()
>> check to allow using a partial match on just the ACPI HID of "MSSL1680"
>> and change the ts_data->acpi_name for the "Chuwi Hi8 Air" accordingly
>> to fix the touchscreen not working on models where it is "MSSL1680:01".
>>
>> Note this drops the length check for I2C_NAME_SIZE. This never was
>> necessary since the ACPI names used are never more then 11 chars and
>> I2C_NAME_SIZE is 20 so the replaced strncmp() would always stop long
>> before reaching I2C_NAME_SIZE.
>>
>> Link: https://linux-hardware.org/?computer=AC4301C0542A
>> Closes: https://github.com/onitake/gsl-firmware/issues/91
>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
>> ---
> 
> Since this is a bug fix, don't you want to add stable tag?

Good point, done.

I've added these to my review-hans (soon to be fixes) branch now.

Regards,

Hans

> 
> Otherwise, it looks good.
> 
> Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> 
>>  drivers/platform/x86/touchscreen_dmi.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/platform/x86/touchscreen_dmi.c b/drivers/platform/x86/touchscreen_dmi.c
>> index 7aee5e9ff2b8..969477c83e56 100644
>> --- a/drivers/platform/x86/touchscreen_dmi.c
>> +++ b/drivers/platform/x86/touchscreen_dmi.c
>> @@ -81,7 +81,7 @@ static const struct property_entry chuwi_hi8_air_props[] = {
>>  };
>>  
>>  static const struct ts_dmi_data chuwi_hi8_air_data = {
>> -	.acpi_name	= "MSSL1680:00",
>> +	.acpi_name	= "MSSL1680",
>>  	.properties	= chuwi_hi8_air_props,
>>  };
>>  
>> @@ -1821,7 +1821,7 @@ static void ts_dmi_add_props(struct i2c_client *client)
>>  	int error;
>>  
>>  	if (has_acpi_companion(dev) &&
>> -	    !strncmp(ts_data->acpi_name, client->name, I2C_NAME_SIZE)) {
>> +	    strstarts(client->name, ts_data->acpi_name)) {
>>  		error = device_create_managed_software_node(dev, ts_data->properties, NULL);
>>  		if (error)
>>  			dev_err(dev, "failed to add properties: %d\n", error);
>