Re: [RFC PATCH 0/6] drm/msm: DSC Electric Boogaloo for sm8[12]50

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On 14/12/2022 21:23, Marijn Suijten wrote:
On 2022-12-14 20:40:06, Dmitry Baryshkov wrote:
On 14/12/2022 01:22, Marijn Suijten wrote:
This preliminary Display Stream Compression support package for
(initially tested on) sm8[12]50 is based on comparing DSC behaviour
between downstream and mainline.  Some new callbacks are added (for
binding blocks on active CTLs), logic bugs are corrected, zeroed struct
members are now assigned proper values, and RM allocation and hw block
retrieval now hand out (or not) DSC blocks without causing null-pointer
dereferences.

Unfortunately it is not yet enough to get rid of completely corrupted
display output on the boards I tested here:
- Sony Xperia 1 (sm8150), 1644x3840 or 1096x2560 pixels;
- Sony Xperia 5II (sm8250), 1080x2520, at 60 or 120Hz;
- (can include more Xperia boards if desired)

Both devices use the DUALPIPE_DSCMERGE topology downstream: dual LM, PP
and DSC, but only a single INTF/encoder/DSI-link.

Hopefully this spawns some community/upstream interest to help rootcause
our corruption issues (after we open a drm/msm report on GitLab for more
appropriate tracking).

The Sony Xperia XZ3 (sdm845) was fully tested and validated with this
series to not cause any regressions (an one of the math fixes now allows
us to change slice_count in the panel driver, which would corrupt
previously).

Marijn Suijten (6):
    drm/msm/dpu1: Implement DSC binding to PP block for CTL V1
    drm/msm/dpu1: Add DSC config for sm8150 and sm8250
    drm/msm/dpu1: Wire up DSC mask for active CTL configuration
    drm/msm/dsi: Use DSC slice(s) packet size to compute word count
    drm/msm/dsi: Flip greater-than check for slice_count and
      slice_per_intf
    drm/msm/dpu: Disallow unallocated (DSC) resources to be returned

General comment: patches with Fixes ideally should come first. Usually
they are picked into -fixes and/or stable kernels. If the Fixes patches
are in the middle of the series, one can not be sure that they do not
have dependencies on previous patches. If there is one, it should
probably be stated clearly to ease work on backporting them.

Ack, I may have rushed these RFC patches straight off my branches onto
the lists in hopes of sparking some suggestions on what may still be
broken or missing to get DSC working on sm[12]50, but will keep this in
mind for v2 after receiving some more review.

That said, any suggestions?


From what I've noticed lately:

- set dsc_version_major/dsc_version_minor
- try using dsc params from 1.2 rater than 1.1 version spec (there is small difference there)

--
With best wishes
Dmitry




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