[SRU][I/raspi][PATCH 10/10] drm/vc4: Increase the core clock to a minimum of 500MHz

Juerg Haefliger juerg.haefliger at canonical.com
Mon Oct 18 15:58:48 UTC 2021

From: Maxime Ripard <maxime at cerno.tech>

BugLink: https://bugs.launchpad.net/bugs/1946368

The core clock needs to be raised temporarily during a modeset to
500MHz. However, the HVS core clock requirement might be higher than
500MHz. This rate will be enforced at the end of the mode setting,
meaning that might might end up with a core clock rate lower than
planned on the first mode set.

Use the maximum value of 500MHz and the HVS core clock rate for our
temporary boost to fix this issue.

Signed-off-by: Maxime Ripard <maxime at cerno.tech>

(forward ported from commit 0a7c2180876d9c7748e055091be21efb959934e2 rpi-5.10.y)
[juergh: new_hvs_state -> hvs_state.]
Signed-off-by: Juerg Haefliger <juergh at canonical.com>
 drivers/gpu/drm/vc4/vc4_kms.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
index 10990d7cc285..fb2465964d46 100644
--- a/drivers/gpu/drm/vc4/vc4_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_kms.c
@@ -348,11 +348,17 @@ vc4_atomic_complete_commit(struct drm_atomic_state *state)
 	if (vc4->hvs && vc4->hvs->hvs5) {
+		unsigned long core_rate = max_t(unsigned long,
+						500000000,
+						hvs_state->core_clock_rate);
+		drm_dbg(dev, "Raising the core clock at %lu Hz\n", core_rate);
 		 * Do a temporary request on the core clock during the
 		 * modeset.
-		core_req = clk_request_start(hvs->core_clk, 500000000);
+		core_req = clk_request_start(hvs->core_clk, core_rate);
 		 * And remove the previous one based on the HVS

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