Re: [PATCH 1/2] iommu/arm-smmu-qcom: Skip the TTBR1 quirk for db820c.

Will Deacon
2021-03-30T09:35:47Z

On Mon, Mar 29, 2021 at 09:02:50PM -0700, Rob Clark wrote:
> On Mon, Mar 29, 2021 at 7:47 AM Will Deacon <will@kernel.org> wrote:
> >
> > On Fri, Mar 26, 2021 at 04:13:02PM -0700, Eric Anholt wrote:
> > > db820c wants to use the qcom smmu path to get HUPCF set (which keeps
> > > the GPU from wedging and then sometimes wedging the kernel after a
> > > page fault), but it doesn't have separate pagetables support yet in
> > > drm/msm so we can't go all the way to the TTBR1 path.
> >
> > What do you mean by "doesn't have separate pagetables support yet"? The
> > compatible string doesn't feel like the right way to determine this.
>
> the compatible string identifies what it is, not what the sw
> limitations are, so in that regard it seems right to me..

Well it depends on what "doesn't have separate pagetables support yet"
means. I can't tell if it's a hardware issue, a firmware issue or a driver
issue.

Will