On Mon, Nov 01, 2021 at 07:55:17PM +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 <hdego...@redhat.com>
> ---
> drivers/video/backlight/lp855x_bl.c | 70 ++++++++++++++++++++++++-----
> 1 file changed, 60 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/video/backlight/lp855x_bl.c
> b/drivers/video/backlight/lp855x_bl.c
> index d1d27d5eb0f2..f075ec84acfb 100644
> --- a/drivers/video/backlight/lp855x_bl.c
> +++ b/drivers/video/backlight/lp855x_bl.c
> @@ -338,10 +339,6 @@ static int lp855x_parse_dt(struct lp855x *lp)
> return -EINVAL;
> }
>
> - pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
> - if (!pdata)
> - return -ENOMEM;
> -
> of_property_read_string(node, "bl-name", &pdata->name);
> of_property_read_u8(node, "dev-ctrl", &pdata->device_control);
> of_property_read_u8(node, "init-brt", &pdata->initial_brightness);
Shouldn't there be a removal of an `lp->pdata = pdata` from somewhere in
this function?
> @@ -379,8 +376,31 @@ static int lp855x_parse_dt(struct lp855x *lp)
> }
> #endif
>
> +static int lp855x_parse_acpi(struct lp855x *lp)
> +{
> + int ret;
> +
> + /*
> + * On ACPI the device has already been initialized by the firmware
Perhaps nitpicking but ideally I'd like "and is in register mode" here
since I presume it can also be assumed that everything with this HID
has adopted that).
Other than these, LGTM.
Daniel.
