[PATCH] Revert "drm/display/dp_mst: Move all payload info into the atomic state"

[Limonciello, Mario]

[Public]



> -----Original Message-----
> From: Linux kernel regression tracking (Thorsten Leemhuis)
> <regressions at leemhuis.info>
> Sent: Friday, January 27, 2023 03:15
> To: Greg KH <gregkh at linuxfoundation.org>; Limonciello, Mario
> <Mario.Limonciello at amd.com>
> Cc: dri-devel at lists.freedesktop.org; stable at vger.kernel.org;
> stanislav.lisovskiy at intel.com; Zuo, Jerry <Jerry.Zuo at amd.com>; amd-
> gfx at lists.freedesktop.org; Lin, Wayne <Wayne.Lin at amd.com>; Guenter
> Roeck <linux at roeck-us.net>; bskeggs at redhat.com
> Subject: Re: [PATCH] Revert "drm/display/dp_mst: Move all payload info into
> the atomic state"
> 
> On 27.01.23 08:39, Greg KH wrote:
> > On Fri, Jan 20, 2023 at 11:51:04AM -0600, Limonciello, Mario wrote:
> >> On 1/20/2023 11:46, Guenter Roeck wrote:
> >>> On Thu, Jan 12, 2023 at 04:50:44PM +0800, Wayne Lin wrote:
> >>>> This reverts commit 4d07b0bc403403438d9cf88450506240c5faf92f.
> >>>>
> >>>> [Why]
> >>>> Changes cause regression on amdgpu mst.
> >>>> E.g.
> >>>> In fill_dc_mst_payload_table_from_drm(), amdgpu expects to
> add/remove payload
> >>>> one by one and call fill_dc_mst_payload_table_from_drm() to update
> the HW
> >>>> maintained payload table. But previous change tries to go through all
> the
> >>>> payloads in mst_state and update amdpug hw maintained table in once
> everytime
> >>>> driver only tries to add/remove a specific payload stream only. The
> newly
> >>>> design idea conflicts with the implementation in amdgpu nowadays.
> >>>>
> >>>> [How]
> >>>> Revert this patch first. After addressing all regression problems caused
> by
> >>>> this previous patch, will add it back and adjust it.
> >>>
> >>> Has there been any progress on this revert, or on fixing the underlying
> >>> problem ?
> >>>
> >>> Thanks,
> >>> Guenter
> >>
> >> Hi Guenter,
> >>
> >> Wayne is OOO for CNY, but let me update you.
> >>
> >> Harry has sent out this series which is a collection of proper fixes.
> >> https://patchwork.freedesktop.org/series/113125/
> >>
> >> Once that's reviewed and accepted, 4 of them are applicable for 6.1.
> >
> > Any hint on when those will be reviewed and accepted?  patchwork
> doesn't
> > show any activity on them, or at least I can't figure it out...
> 
> I didn't look closer (hence please correct me if I'm wrong), but the
> core changes afaics are in the DRM pull airlied send a few hours ago to
> Linus (note the "amdgpu […] DP MST fixes" line):
> 
> https://lore.kernel.org/all/CAPM%3D9tzuu4xnx6T5v7sKsK%2BA5HEaPOc1ie
> MyzNSYQZGztJ%3D6Qw at mail.gmail.com/

That's right.  There are 4 commits in that PR with the appropriate stable tags
that should fix the majority of the MST issues introduced in 6.1 by 4d07b0bc40340
("drm/display/dp_mst: Move all payload info into the atomic state"):

      drm/amdgpu/display/mst: Fix mst_state->pbn_div and slot count assignments
      drm/amdgpu/display/mst: limit payload to be updated one by one
      drm/amdgpu/display/mst: update mst_mgr relevant variable when long HPD
      drm/display/dp_mst: Correct the kref of port.

There will be follow ups for any remaining corner cases.

> 
> Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
> --
> Everything you wanna know about Linux kernel regression tracking:
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