[PATCH 2/2] drm/amdgpu: Add modeset module option

[Ilia Mirkin]

On Sun, Apr 1, 2018 at 1:39 PM, Christian König
<christian.koenig at amd.com> wrote:
> Am 30.03.2018 um 22:45 schrieb Takashi Iwai:
>>
>> amdgpu driver lacks of modeset module option other drm drivers provide
>> for enforcing or disabling the driver load.  Interestingly, the
>> amdgpu_mode variable declaration is already found in the header file,
>> but the actual implementation seems to have been forgotten.
>>
>> This patch adds the missing piece.
>
>
> NAK, modesetting is mandatory for amdgpu and we should probably remove the
> option to disable it from other DRM drivers without UMS support as well
> (pretty much all of them now).
>
> If you want to prevent a driver from loading I think the correct way to do
> so is to give modprobe.blacklist=amdgpu on the kernel commandline.
>
> That would remove the possibility to prevent the driver from loading when it
> is compiled in, but I don't see much of a problem with that.

Having a way to kill the graphics driver is a very useful debugging
tool, and also a quick and easy way to get out of an unpleasant
situation where graphics are messed up / system hangs / etc. The
modprobe blacklist kernel arg only works in certain environments (and
only if it's a module).

Every other DRM driver has this and this is a well-documented
workaround for "graphics are messed up when I install linux", why not
allow a uniform experience for the end users who are just trying to
get their systems up and running?

  -ilia