Re: [PATCH] ACPI / video: update the skip case for acpi_video_device_in_dod

[Aaron Lu <aaron.lu@intel.com>]

On 12/15/2014 05:02 PM, Jani Nikula wrote:
> On Mon, 15 Dec 2014, Aaron Lu <aaron.lu@intel.com> wrote:
>> If the firmware has declared more than 8 video output devices, and the
>> one that control the internal panel's backlight is listed after the
>> first 8 output devices, the _DOD will not include it due to the current
>> i915 operation region implementation. As a result, we will not create a
>> backlight device for it while we should. Solve this problem by special
>> case the firmware that has 8+ output devices in that if we see such a
>> firmware, we do not test if the device is in _DOD list. The creation of
>> the backlight device will also enable the firmware to emit events on
>> backlight hotkey press when the acpi_osi= cmdline option is specified on
>> those affected ASUS laptops.
>>
>> Buglink: https://bugzilla.kernel.org/show_bug.cgi?id=70241
>> Reported-and-tested-by: Oleksij Rempel <linux@rempel-privat.de>
>> Reported-and-tested-by: Dmitry Tunin <hanipouspilot@gmail.com>
>> Reported-and-tested-by: Jimbo <jaime.91@hotmail.es>
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Aaron Lu <aaron.lu@intel.com>
> 
> Obviously I'd like to have the proper information in the opregion
> DIDL/CADL fields, but it's not going to happen soon, nor is it going to
> fit under stable size limits.
> 
> I like the simplicity here. FWIW,
> 
> Acked-by: Jani Nikula <jani.nikula@intel.com>

Thanks :-)

BTW, this patch is more of a fix for my previous commit 0b8db271f159
("ACPI / video: check _DOD list when creating backlight devices") that
made the acpi_video interface disappear on these affected laptops so I
would like to fix it quickly. And I agree that a proper implementation
of the DIDL/CADL list is needed so that people can get rid of the
acpi_osi= cmdline option they currently need to get hotkey events.

Regards,
Aaron

> 
>> ---
>>  drivers/acpi/video.c | 10 ++++++++--
>>  1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
>> index 8b844931b936..c72e79d2c5ad 100644
>> --- a/drivers/acpi/video.c
>> +++ b/drivers/acpi/video.c
>> @@ -155,6 +155,7 @@ struct acpi_video_bus {
>>  	u8 dos_setting;
>>  	struct acpi_video_enumerated_device *attached_array;
>>  	u8 attached_count;
>> +	u8 child_count;
>>  	struct acpi_video_bus_cap cap;
>>  	struct acpi_video_bus_flags flags;
>>  	struct list_head video_device_list;
>> @@ -1176,8 +1177,12 @@ static bool acpi_video_device_in_dod(struct acpi_video_device *device)
>>  	struct acpi_video_bus *video = device->video;
>>  	int i;
>>  
>> -	/* If we have a broken _DOD, no need to test */
>> -	if (!video->attached_count)
>> +	/*
>> +	 * If we have a broken _DOD or we have more than 8 output devices
>> +	 * under the graphics controller node that we can't proper deal with
>> +	 * in the operation region code currently, no need to test.
>> +	 */
>> +	if (!video->attached_count || video->child_count > 8)
>>  		return true;
>>  
>>  	for (i = 0; i < video->attached_count; i++) {
>> @@ -1430,6 +1435,7 @@ acpi_video_bus_get_devices(struct acpi_video_bus *video,
>>  			dev_err(&dev->dev, "Can't attach device\n");
>>  			break;
>>  		}
>> +		video->child_count++;
>>  	}
>>  	return status;
>>  }
>> -- 
>> 2.1.0
>>
> 

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