Hi Daniel, Thank you for the quick review of this series. On 11/2/21 13:22, Daniel Thompson wrote: > 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 <hdegoede@xxxxxxxxxx> >> --- >> 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? Ack, fixed for v2. >> @@ -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). Nope not nitpicking, that is a good point, also fixed for v2. Regards, Hans