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88 lines
2.9 KiB
Diff
88 lines
2.9 KiB
Diff
From 8c994de768f64b6697798c7b08f25b05485195c9 Mon Sep 17 00:00:00 2001
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From: Maxime Ripard <maxime@cerno.tech>
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Date: Mon, 30 Aug 2021 15:30:41 +0200
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Subject: [PATCH 588/634] drm/vc4: Wait for the commit before starting our
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clock request
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Several DRM/KMS atomic commits can run in parallel if they affect
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different CRTC. These commits share the global HVS state, so we have
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some code to make sure we run commits in sequence. This synchronization
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code is one of the first thing that runs in vc4_atomic_commit_tail().
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Another constraints we have is that we need to make sure the HVS clock
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gets a boost during the commit. That code relies on clk_requests and
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will remove the old requests and start a new one. We also need another,
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temporary, request for the duration of the commit.
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The algorithm is thus to start a temporary request, drop the previous
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one, do the commit, start a new request for the current mode, and
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finally drop the temporary request.
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However, the part that takes a temporary request and drops the older one
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runs before the commit synchronization code.
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Thus, under the proper conditions, we can end up dropping twice the old
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request, resulting in an use-after-free.
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To avoid it, let's move the clock setup in the protected section.
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Signed-off-by: Maxime Ripard <maxime@cerno.tech>
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---
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drivers/gpu/drm/vc4/vc4_kms.c | 34 ++++++++++++++++++++--------------
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1 file changed, 20 insertions(+), 14 deletions(-)
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diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
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index cc905b8c3282..8c63b962b2e6 100644
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--- a/drivers/gpu/drm/vc4/vc4_kms.c
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+++ b/drivers/gpu/drm/vc4/vc4_kms.c
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@@ -369,20 +369,6 @@ static void vc4_atomic_commit_tail(struct drm_atomic_state *state)
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vc4_hvs_mask_underrun(dev, vc4_crtc_state->assigned_channel);
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}
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- if (vc4->hvs && vc4->hvs->hvs5) {
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- unsigned long core_rate = max_t(unsigned long,
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- 500000000,
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- new_hvs_state->core_clock_rate);
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-
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- core_req = clk_request_start(hvs->core_clk, core_rate);
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-
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- /*
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- * And remove the previous one based on the HVS
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- * requirements if any.
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- */
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- clk_request_done(hvs->core_req);
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- }
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-
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for_each_old_crtc_in_state(state, crtc, old_crtc_state, i) {
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struct vc4_crtc_state *vc4_crtc_state =
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to_vc4_crtc_state(old_crtc_state);
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@@ -407,6 +393,26 @@ static void vc4_atomic_commit_tail(struct drm_atomic_state *state)
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drm_crtc_commit_put(commit);
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}
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+ if (vc4->hvs && vc4->hvs->hvs5) {
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+ unsigned long core_rate = max_t(unsigned long,
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+ 500000000,
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+ new_hvs_state->core_clock_rate);
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+
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+ drm_dbg(dev, "Raising the core clock at %lu Hz\n", core_rate);
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+
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+ /*
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+ * Do a temporary request on the core clock during the
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+ * modeset.
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+ */
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+ core_req = clk_request_start(hvs->core_clk, core_rate);
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+
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+ /*
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+ * And remove the previous one based on the HVS
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+ * requirements if any.
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+ */
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+ clk_request_done(hvs->core_req);
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+ }
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+
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drm_atomic_helper_commit_modeset_disables(dev, state);
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vc4_ctm_commit(vc4, state);
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--
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2.33.1
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