On Thu, 2019-08-08 at 18:17 +0000, William Lewis wrote: > On 8/8/19 1:04 PM, Lyude Paul wrote: > > I -thought- I had fixed this entirely, but it looks like that I didn't > > test this thoroughly enough as we apparently still make one big mistake > > with nv50_msto_atomic_check() - we don't handle the following scenario: > > > > * CRTC #1 has n VCPI allocated to it, is attached to connector DP-4 > > which is attached to encoder #1. enabled=y active=n > > * CRTC #1 is changed from DP-4 to DP-5, causing: > > * DP-4 crtc=#1→NULL (VCPI n→0) > > * DP-5 crtc=NULL→#1 > > * CRTC #1 steals encoder #1 back from DP-4 and gives it to DP-5 > > * CRTC #1 maintains the same mode as before, just with a different > > connector > > * mode_changed=n connectors_changed=y > > (we _SHOULD_ do VCPI 0→n here, but don't) > > > > Once the above scenario is repeated once, we'll attempt freeing VCPI > > from the connector that we didn't allocate due to the connectors > > changing, but the mode staying the same. Sigh. > > > > Since nv50_msto_atomic_check() has broken a few times now, let's rethink > > things a bit to be more careful: limit both VCPI/PBN allocations to > > mode_changed || connectors_changed, since neither VCPI or PBN should > > ever need to change outside of routing and mode changes. > > > > Signed-off-by: Lyude Paul <[email protected]> > > Reported-by: Bohdan Milar <[email protected]> > > Tested-by: Bohdan Milar <[email protected]> > > Fixes: 232c9eec417a ("drm/nouveau: Use atomic VCPI helpers for MST") > > References: 412e85b60531 ("drm/nouveau: Only release VCPI slots on mode > > changes") > > Cc: Lyude Paul <[email protected]> > > Cc: Ben Skeggs <[email protected]> > > Cc: Daniel Vetter <[email protected]> > > Cc: David Airlie <[email protected]> > > Cc: Jerry Zuo <[email protected]> > > Cc: Harry Wentland <[email protected]> > > Cc: Juston Li <[email protected]> > > Cc: Laurent Pinchart <[email protected]> > > Cc: Karol Herbst <[email protected]> > > Cc: Ilia Mirkin <[email protected]> > > Cc: <[email protected]> # v5.1+ > > --- > > drivers/gpu/drm/nouveau/dispnv50/disp.c | 22 +++++++++++++--------- > > 1 file changed, 13 insertions(+), 9 deletions(-) > > > > diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c > > b/drivers/gpu/drm/nouveau/dispnv50/disp.c > > index 126703816794..5d23ab8e4917 100644 > > --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c > > +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c > > @@ -771,16 +771,20 @@ nv50_msto_atomic_check(struct drm_encoder *encoder, > > struct nv50_head_atom *asyh = nv50_head_atom(crtc_state); > > int slots; > > > > - /* When restoring duplicated states, we need to make sure that the > > - * bw remains the same and avoid recalculating it, as the connector's > > - * bpc may have changed after the state was duplicated > > - */ > > - if (!state->duplicated) > > - asyh->dp.pbn = > > - drm_dp_calc_pbn_mode(crtc_state->adjusted_mode.clock, > > - connector->display_info.bpc * 3); > drm_dp_calc_pbn_mode(clock, bpp) > > + if (crtc_state->mode_changed || crtc_state->connectors_changed) { > > + /* > > + * When restoring duplicated states, we need to make sure that > > + * the bw remains the same and avoid recalculating it, as the > > + * connector's bpc may have changed after the state was > > + * duplicated > > + */ > > + if (!state->duplicated) { > > + const int bpp = connector->display_info.bpc * 3; > > + const int clock = crtc_state->adjusted_mode.clock; > > + > > + asyh->dp.pbn = drm_dp_calc_pbn_mode(bpp, clock); > drm_dp_calc_pbn_mode(bpp, clock) > > + } > > > > - if (crtc_state->mode_changed) { > > slots = drm_dp_atomic_find_vcpi_slots(state, &mstm->mgr, > > mstc->port, > > asyh->dp.pbn); > Which is correct?
!?!?!?!?!?!? I am actually seriously confused as to how this code did not break when I tested it, as I certainly reversed the two arguments here by accident. Looks like we need to add more error checking for drm_dp_calc_pbn_mode. Thank you for catching this, I'll respin this and send out a new version in a second > _______________________________________________ > Nouveau mailing list > [email protected] > https://lists.freedesktop.org/mailman/listinfo/nouveau _______________________________________________ Nouveau mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/nouveau
