Re: [PATCH v4 0/3] Selective Fetch and async flip

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Dec 10, 2025 at 06:57:41AM +0000, Hogander, Jouni wrote:
> On Wed, 2025-12-10 at 08:42 +0200, Ville Syrjälä wrote:
> > On Wed, Dec 10, 2025 at 06:23:34AM +0000, Hogander, Jouni wrote:
> > > On Tue, 2025-12-09 at 20:26 +0200, Ville Syrjälä wrote:
> > > > On Thu, Dec 04, 2025 at 09:07:15AM +0200, Jouni Högander wrote:
> > > > > This patch set contains fixes for Selective Fetch async flip
> > > > > sequences. On async flip selective fetch is choosing full frame
> > > > > update. Also subsequent flip/update is still using full frame
> > > > > update
> > > > > to ensure plane with pending async flip is not taken in to
> > > > > selective
> > > > > fetch/update.
> > > > > 
> > > > > v4:
> > > > >   - rework if-else if to if-if
> > > > >   - added comment updated
> > > > >   - check crtc_state->async_flip_planes in
> > > > >     psr2_sel_fetch_pipe_state_supported
> > > > > v3:
> > > > >   - rebase
> > > > >   - fix old_crtc_state->pipe_srcsz_early_tpt
> > > > >   - fix using intel_atomic_get_new_crtc_state
> > > > > v2:
> > > > >   - check also crtc_state->async_flip_planes in
> > > > >     psr2_sel_fetch_plane_state_supported
> > > > > 
> > > > > Jouni Högander (3):
> > > > >   drm/i915/psr: Set plane id bit in crtc_state-
> > > > > >async_flip_planes
> > > > > for
> > > > >     PSR
> > > > >   drm/i915/psr: Perform full frame update on async flip
> > > > >   drm/i915/psr: Allow async flip when Selective Fetch enabled
> > > > 
> > > > Series is
> > > > Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > > 
> > > > When testing this I saw that we get stuck into full frame mode
> > > > all the time. But that seems to be a pre-existing issues caused
> > > > by the broken selective fetch area calculation code. I suppose
> > > > now that I have a laptop with a PSR2 panel I might have to dig
> > > > out
> > > > that branch of mine where I attempted to rewrite the whoile thing
> > > > and figure out what was wrong with it...
> > > > 
> > > 
> > > What is the SW setup you are using and what kind of testing you are
> > > doing? Could it be related to frontbuffer tracking?
> > 
> > I just have Xorg running w/o a compositor and then running
> > 'vblank_mode=0 glxgears -fullscreen'. The last tests were done
> > using mate/marco as the window manager, but I suppose it might be
> > reproducible w/o any window manager as well.
> > 
> > I was monitoring the full vs. partial update state by just polling
> > the PSR_MAN_TRACK_CTL (or whatever it's called) register. Might
> > actually be a decent idea to add something into the debufs status
> > file for that, given that the register layout is rather platform
> > specific.
> > 
> > I sprinkled a few debugs in the driver and it generally seemed to end
> > up in the 'if (crtc_state->psr2_su_area.y1 == -1) -> full_update'
> > case, which doesn't really surprise given that the code is very
> > confused about coordinate spaces.
> 
> Thank you for the description. I will try to reproduce. What does that
> vblank_mode=0?

It forces vsync off regardless of what the application asks for.

I was going to point you at the Mesa environment variable docs, but
surprisingly vblank_mode doesn't appear to be documented there.

-- 
Ville Syrjälä
Intel