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SubjectRe: [PATCH 3/3] backlight: lp855x: Add support ACPI enumeration
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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@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?

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

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