Re: [igt-dev] [PATCH i-g-t] i915/pm_backlight: ensure driver is loaded before checking backlight

[Jani Nikula <jani.nikula@intel.com>]

On Tue, 11 Feb 2020, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> Quoting Jani Nikula (2020-02-11 11:16:34)
>> Checking the existence of the backlight interface before ensuring the
>> driver is loaded skips whenever the test is run without the driver
>> loaded. None of the tests would work properly if they were run as the
>> first thing or after tests that unload the driver.
>> 
>> Open the driver (and thus probe it as needed) as the first thing.
>
> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
>
>> (This is the low-hanging fruit. A proper test for skipping would be
>> based on the presence of embedded displays, not based on the presence of
>> the interface we're aiming to test.)
>
> Slightly different test idea. Here we say this is a test for particular
> interface, what you have in mind is a requirement that if available HW,
> the kernel *must* provide an interface. (I don't really like userspace
> demanding the kernel makes something available, for the cases were it
> really can't be done due to some flaw or another. From the HW vendor
> perspective, such a conformance test is understandable -- but we are
> focusing on the interfaces the kernel does expose and verifying that
> work as expected.)

That's fair. I'll drop the parenthesized paragraph before pushing.

Thanks for the reviews.

BR,
Jani.


-- 
Jani Nikula, Intel Open Source Graphics Center
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