Hi,
On 11-06-15 13:47, Pali Rohár wrote:
> On Wednesday 10 June 2015 15:01:19 Hans de Goede wrote:
>> Port the backlight selection logic to the new backlight interface
>> selection API.
>>
>> Signed-off-by: Hans de Goede <hdego...@redhat.com>
>> ---
>> drivers/platform/x86/dell-laptop.c | 6 ++----
>> 1 file changed, 2 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/platform/x86/dell-laptop.c
>> b/drivers/platform/x86/dell-laptop.c
>> index d688d80..db2e031 100644
>> --- a/drivers/platform/x86/dell-laptop.c
>> +++ b/drivers/platform/x86/dell-laptop.c
>> @@ -31,6 +31,7 @@
>> #include <linux/slab.h>
>> #include <linux/debugfs.h>
>> #include <linux/seq_file.h>
>> +#include <acpi/video.h>
>> #include "../../firmware/dcdbas.h"
>>
>> #define BRIGHTNESS_TOKEN 0x7d
>> @@ -1921,10 +1922,7 @@ static int __init dell_init(void)
>> &dell_debugfs_fops);
>>
>> #ifdef CONFIG_ACPI
>> - /* In the event of an ACPI backlight being available, don't
>> - * register the platform controller.
>> - */
>> - if (acpi_video_backlight_support())
>> + if (acpi_video_get_backlight_type() != acpi_backlight_vendor)
>> return 0;
>> #endif
>>
>
> Now I'm thinking... Is this correct condition? And do we need it? This
> Dell backlight interface works even if ACPI or intel i915 driver
> controls backlight. Why we should prevent dell-laptop.ko to register
> Dell backlight interface if ACPI video already register one? And why not
> prevent when intel i915 driver register another?
3 things:
1) This is mostly a cleanup series, it does not make any behavioral
changes (other then renaming the kernelcmdline option and we've
already discussed fixing that).
2) All 3 drivers ultimately bit-bang the same hardware, we really should
have only one driver banging the hardware, so
if (acpi_video_get_backlight_type() != acpi_backlight_vendor)
return 0;
Definitely is the right thing todo here.
3) You're right that the intel_backlight still registering even if
acpi_video_get_backlight_type() != acpi_backlight_native is weird, but
that is how it was before this series, and userspace prefers firmware
type backlight sysfs entries over platform /raw ones so it will
automatically pick the right one. We should consider not registering
the backlight sysfs class interface from the intel code when
acpi_video_get_backlight_type() != acpi_backlight_native but that is
something for later...
Regards,
Hans
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