The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 0c980a006d3fbee86c4d0698f66d6f5381831787 Mon Sep 17 00:00:00 2001

From: Maxime Ripard maxime@cerno.tech Date: Wed, 17 Nov 2021 10:45:22 +0100 Subject: [PATCH] drm/vc4: kms: Wait for the commit before increasing our clock rate

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

diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c index f0b3e4cf5bce..764ddb41a4ce 100644 --- 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(struct drm_atomic_state *state) 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(struct drm_atomic_state *state) 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);