On Fri, Sep 15, 2023 at 11:29 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
>
> The Xiaomi Mi Pad 2 is currently listed under the:
> "Models which should use the vendor backlight interface,
> because of broken ACPI video backlight control." section.
>
> But this is not 100% correct. The Xiaomi Mi Pad 2 is one of a set of
> x86 tablets which shipped with Android as factory OS. These tablets
> have a TI LP8557 backlight controller with its PWM input _not_
> connected to the PMIC or chipset (LPSS) PWM output.
>
> Instead the backlight can be controlled by configuring the LP8557
> for direct control through its brightness I2C register and then
> using the lp855x driver.
>
> This setup means that neither i915's native or acpi_video backlight
> control works, so a "vendor" quirk is added for these tablets to
> disable both the native and acpi_video backlight devices, but these
> devices do not use vendor control in the typical meaning of
> vendor specific SMBIOS or ACPI calls being used.
>
> This patch is a preparation patch for adding "vendor" quirks
> for a couple more such tablet models.
>
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
> drivers/acpi/video_detect.c | 26 ++++++++++++++++++--------
> 1 file changed, 18 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c
> index 442396f6ed1f..889902a4fdfe 100644
> --- a/drivers/acpi/video_detect.c
> +++ b/drivers/acpi/video_detect.c
> @@ -229,14 +229,6 @@ static const struct dmi_system_id video_detect_dmi_table[] = {
> DMI_MATCH(DMI_BOARD_NAME, "NC210/NC110"),
> },
> },
> - {
> - .callback = video_detect_force_vendor,
> - /* Xiaomi Mi Pad 2 */
> - .matches = {
> - DMI_MATCH(DMI_SYS_VENDOR, "Xiaomi Inc"),
> - DMI_MATCH(DMI_PRODUCT_NAME, "Mipad2"),
> - },
> - },
>
> /*
> * Models which should use the vendor backlight interface,
> @@ -799,6 +791,24 @@ static const struct dmi_system_id video_detect_dmi_table[] = {
> DMI_MATCH(DMI_PRODUCT_NAME, "Vostro 15 3535"),
> },
> },
> +
> + /*
> + * x86 android tablets which directly control the backlight through
> + * an external backlight controller, typically TI's LP8557.
> + * The backlight is directly controlled by the lp855x driver on these.
> + * This setup means that neither i915's native nor acpi_video backlight
> + * control works. Add a "vendor" quirk to disable both. Note these
> + * devices do not use vendor control in the typical meaning of
> + * vendor specific SMBIOS or ACPI calls being used.
> + */
> + {
> + .callback = video_detect_force_vendor,
> + /* Xiaomi Mi Pad 2 */
> + .matches = {
> + DMI_MATCH(DMI_SYS_VENDOR, "Xiaomi Inc"),
> + DMI_MATCH(DMI_PRODUCT_NAME, "Mipad2"),
> + },
> + },
> { },
> };
>
> --
Applied as 6.7 material along with the [2/2], thanks!
