Re: [PATCH 0/3] Experimental freesync video mode optimization

From: Daniel Vetter <daniel@ffwll.ch>
To: Pekka Paalanen <ppaalanen@gmail.com>
Cc: stylon.wang@amd.com, thong.thai@amd.com, shashank.sharma@amd.com,
	dri-devel@lists.freedesktop.org, nicholas.kazlauskas@amd.com,
	Aurabindo Pillai <aurabindo.pillai@amd.com>,
	amd-gfx@lists.freedesktop.org, wayne.lin@amd.com,
	alexander.deucher@amd.com, christian.koenig@amd.com
Subject: Re: [PATCH 0/3] Experimental freesync video mode optimization
Date: Fri, 22 Jan 2021 10:42:53 +0100	[thread overview]
Message-ID: <YAqeHZlDBrgALLo9@phenom.ffwll.local> (raw)
In-Reply-To: <20210122103248.779e70bf@eldfell>

On Fri, Jan 22, 2021 at 10:32:48AM +0200, Pekka Paalanen wrote:
> On Tue, 19 Jan 2021 10:50:26 -0500
> Aurabindo Pillai <aurabindo.pillai@amd.com> wrote:
> 
> > Changes in V5
> > =============
> > 
> > * More info in commit messages on the rationale of changes being added
> > to the kernel.
> > * Minor fixes
> 
> Hi,
> 
> thank you for adding the explanations in the commit messages I asked
> for. It is now up to DRM maintainers to determine if this is
> conceptually fine.
> 
> I do see that apparently setting the opt-in option does not yet taint
> the kernel although Daniel Vetter suggested it might be a good idea. I
> guess tainting the kernel would make it easier to remove this feature
> in the future because it would be easier to dismiss people that claim a
> kernel regression due to the removal.

Reading the descriptions I'm honestly not sure why this isn't enabled by
default?

Maybe the explanations should also capture why this is maybe not a good
idea ...
-Daniel

> 
> 
> Thanks,
> pq
> 
> 
> > --
> > 
> > This patchset enables freesync video mode usecase where the userspace
> > can request a freesync compatible video mode such that switching to this
> > mode does not trigger blanking.
> > 
> > This feature is guarded by a module parameter which is disabled by
> > default. Enabling this paramters adds additional modes to the driver
> > modelist, and also enables the optimization to skip modeset when using
> > one of these modes.
> > 
> > --
> > 
> > Aurabindo Pillai (3):
> >   drm/amd/display: Add module parameter for freesync video mode
> >   drm/amd/display: Add freesync video modes based on preferred modes
> >   drm/amd/display: Skip modeset for front porch change
> > 
> >  drivers/gpu/drm/amd/amdgpu/amdgpu.h           |   1 +
> >  drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c       |  12 +
> >  .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 401 ++++++++++++++++--
> >  .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |   3 +
> >  4 files changed, 382 insertions(+), 35 deletions(-)
> > 
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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