From patchwork Fri Aug 9 00:53:05 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [v2] drm/nouveau: Only recalculate PBN/VCPI on mode/connector changes From: Lyude Paul X-Patchwork-Id: 322786 Message-Id: <20190809005307.18391-1-lyude@redhat.com> To: nouveau@lists.freedesktop.org Cc: Bohdan Milar , linux-kernel@vger.kernel.org, David Airlie , Daniel Vetter , dri-devel@lists.freedesktop.org, William Lewis , stable@vger.kernel.org, Karol Herbst , Jerry Zuo , Ben Skeggs , David Airlie , Juston Li , Laurent Pinchart Date: Thu, 8 Aug 2019 20:53:05 -0400 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. Changes since v1: * Fix accidental reversal of clock and bpp arguments in drm_dp_calc_pbn_mode() - William Lewis Signed-off-by: Lyude Paul Reported-by: Bohdan Milar Tested-by: Bohdan Milar Fixes: 232c9eec417a ("drm/nouveau: Use atomic VCPI helpers for MST") References: 412e85b60531 ("drm/nouveau: Only release VCPI slots on mode changes") Cc: Lyude Paul Cc: Ben Skeggs Cc: Daniel Vetter Cc: David Airlie Cc: Jerry Zuo Cc: Harry Wentland Cc: Juston Li Cc: Laurent Pinchart Cc: Karol Herbst Cc: Ilia Mirkin Cc: # v5.1+ Acked-by: Ben Skeggs --- 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..5c36c75232e6 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); + 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(clock, bpp); + } - if (crtc_state->mode_changed) { slots = drm_dp_atomic_find_vcpi_slots(state, &mstm->mgr, mstc->port, asyh->dp.pbn);