[PATCH v2 3/3] backlight: lp855x: Add support ACPI enumeration

[Daniel Thompson]

On Tue, Nov 02, 2021 at 11:55:04PM +0100, Hans de Goede wrote:
> The Xiaomi Mi Pad 2 tablet uses an ACPI enumerated LP8556 backlight
> controller for its LCD-panel, with a Xiaomi specific ACPI HID of
> "XMCC0001", add support for this.
> 
> Note the new "if (id)" check also fixes a NULL pointer deref when a user
> tries to manually bind the driver from sysfs.
> 
> When CONFIG_ACPI is disabled acpi_match_device() will always return NULL,
> so the lp855x_parse_acpi() call will get optimized away.
> 
> Signed-off-by: Hans de Goede <hdegoede at redhat.com>

Reviewed-by: Daniel Thompson <daniel.thompson at linaro.org>


Daniel.