Re: [RFC PATCH 00/14] CAMSS support for MSM8974

Brian Masney
2022-05-23T18:47:53Z

On Mon, May 23, 2022 at 03:39:53PM +0300, Dmitry Baryshkov wrote:
> On 22/05/2022 19:27, Luca Weiss wrote:
> > This RFC series adds support for CAMSS and CCI that are found on
> > msm8974, including the OV8865 found on the FP2.
> >
> > The only reason it's marked RFC is that CAMSS doesn't behave properly on
> > this SoC without the last commit which is obviously not upstreamable.
> > Not sure if this should be a blocker for including most of the other
> > patches because other than that it seems to work fine and I can get a
> > picture from the camera sensor. When/if msm8974 gets IOMMU support I
> > hope this should be resolved and it works without this hack.
> >
> > I think at least the CCI patches could get applied as they're not
> > dependent on the CAMSS hack?
>
> I'd also vote for the camcc patches to be applied.
>
> As for the camss, I'd suggest to get them verified to work properly with a
> hacked/non-upstreamable/etc. IOMMU driver if one exists. Otherwise we can
> easily get into a situation where we merge up code that contains bugs
> itself.

Last I checked, there's no IOMMU driver for msm8974 that works with an
upstream kernel at the moment. About 2 years ago, I took a stab at
attempting to enable IOMMU for the display and ran into some issues that
I documented at:

https://lore.kernel.org/lkml/20200109002606.35653-1-masneyb@onstation.org/

I'm not familiar with this part of the hardware and haven't had time
since then to look into this further.

Brian