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openmptcprouter/6.12/target/linux/bcm27xx/patches-6.12/950-0651-drm-vc4-Add-a-delay-after-disabling-hdmi-phy-output.patch
Ycarus (Yannick Chabanois) bdb9b0046f Add bcm27xx 6.12 test support
2024-12-20 14:17:26 +01:00

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1.1 KiB
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From 084560b8c42ec2fde7b6c0eb5d8e6fa46878bdeb Mon Sep 17 00:00:00 2001
From: Dom Cobley <popcornmix@gmail.com>
Date: Mon, 12 Aug 2024 13:31:58 +0100
Subject: [PATCH 651/697] drm/vc4: Add a delay after disabling hdmi phy output
There appears to be a requirement for some devices
(I'm testing with a 8K VRROOM 40Gbps HDMI switch)
for a measable delay between removing the hdmi phy output from
the old mode, to enabling the hdmi phy output for the new mode.
Without the delay, a mode switch has a small change of getting a permanent
'no signal', which requires a subsequent mode switch or a unplug/replug
to redetect.
Switching between 4kp24/25/30 modes fails about 5% of time in my testing.
Add a delay to make it impossible to switch faster than this.
Signed-off-by: Dom Cobley <popcornmix@gmail.com>
---
drivers/gpu/drm/vc4/vc4_crtc.c | 1 +
1 file changed, 1 insertion(+)
--- a/drivers/gpu/drm/vc4/vc4_crtc.c
+++ b/drivers/gpu/drm/vc4/vc4_crtc.c
@@ -647,6 +647,7 @@ static void vc4_crtc_atomic_disable(stru
* someone was waiting it.
*/
vc4_crtc_send_vblank(crtc);
+ msleep(20);
}
static void vc4_crtc_atomic_enable(struct drm_crtc *crtc,