From: Maxime Ripard maxime@cerno.tech
commit 0c980a006d3fbee86c4d0698f66d6f5381831787 upstream.
Several DRM/KMS atomic commits can run in parallel if they affect different CRTC. These commits share the global HVS state, so we have some code to make sure we run commits in sequence. This synchronization code is one of the first thing that runs in vc4_atomic_commit_tail().
Another constraints we have is that we need to make sure the HVS clock gets a boost during the commit. That code relies on clk_set_min_rate and will remove the old minimum and set a new one. We also need another, temporary, minimum for the duration of the commit.
The algorithm is thus to set a temporary minimum, drop the previous one, do the commit, and finally set the minimum for the current mode.
However, the part that sets the temporary minimum and drops the older one runs before the commit synchronization code.
Thus, under the proper conditions, we can end up mixing up the minimums and ending up with the wrong one for our current step.
To avoid it, let's move the clock setup in the protected section.
Fixes: d7d96c00e585 ("drm/vc4: hvs: Boost the core clock during modeset") Signed-off-by: Maxime Ripard maxime@cerno.tech Reviewed-by: Dave Stevenson dave.stevenson@raspberrypi.com Tested-by: Jian-Hong Pan jhp@endlessos.org Link: https://lore.kernel.org/r/20211117094527.146275-2-maxime@cerno.tech Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/vc4/vc4_kms.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/gpu/drm/vc4/vc4_kms.c +++ b/drivers/gpu/drm/vc4/vc4_kms.c @@ -353,9 +353,6 @@ static void vc4_atomic_commit_tail(struc vc4_hvs_mask_underrun(dev, vc4_crtc_state->assigned_channel); }
- if (vc4->hvs->hvs5) - clk_set_min_rate(hvs->core_clk, 500000000); - old_hvs_state = vc4_hvs_get_old_global_state(state); if (!old_hvs_state) return; @@ -377,6 +374,9 @@ static void vc4_atomic_commit_tail(struc drm_err(dev, "Timed out waiting for commit\n"); }
+ if (vc4->hvs->hvs5) + clk_set_min_rate(hvs->core_clk, 500000000); + drm_atomic_helper_commit_modeset_disables(dev, state);
vc4_ctm_commit(vc4, state);