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

[Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>]

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?

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);

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer