[PATCH] drm/radeon: deprecate and remove KFD interface

[Oded Gabbay]

On Wed, Nov 29, 2017 at 1:16 PM, Michel Dänzer <michel at daenzer.net> wrote:
> On 2017-11-01 09:31 AM, Oded Gabbay wrote:
>> ok, taken to -next.
>
> This change broke the radeon driver on my Kaveri laptop. The gdm login
> screen works, but logging into the GNOME on Xorg session quickly results
> in a GPU hang and associated badness, see the attached dmesg.
>
> Reverting this change on top of drm-next makes it work again.
>
> On a hunch, I've tried reverting commits 62a7b7fbd08e ("drm/radeon:
> reduce number of free VMIDs and pipes in KV") and 28b57b856b63
> ("drm/radeon/cik: Don't touch int of pipes 1-7"), but no luck.
>
> Any ideas for what else is missing?
>
> Note that the amdkfd driver isn't actually active anyway, because I'm
> disabling the IOMMU. Is it possible that it's still doing or triggering
> some needed HW setup before it bails in that case?
>
>
> P.S. Assuming we can fix this without reverting, maybe we could also
> remove rdev->grbm_idx_mutex again?
>
> --
> Earthling Michel Dänzer               |               http://www.amd.com
> Libre software enthusiast             |             Mesa and X developer

Hi Michel,
Even without IOMMU, amdkfd will initialize the module and internal
structures per device, up to the point where it tries to register a
callback with the iommu driver.
If IOMMU is disabled, it will fail then with the following error
message (in dmesg): "error getting iommu info. is the iommu enabled?"

Having said that, it doesn't initialize anything in the device H/W
itself, so I find this very weird.

I looked at the patch itself again and I don't see anything suspicious.

I'll try to resurrect my Kaveri machine to check this, but it will
take some time.

Oded