linux (RPi): add PR6309 to fix occasional "no signal" after modeswitch

Signed-off-by: Matthias Reichl <hias@horus.com>

packages/linux/patches/raspberrypi/linux-010-pr6309-fix-no-signal-after-modeswitch.patch

@@ -0,0 +1,100 @@
+From 733e7a51a128e950d210ef3652f5427e4179e17a Mon Sep 17 00:00:00 2001
+From: Dom Cobley <popcornmix@gmail.com>
+Date: Mon, 12 Aug 2024 13:31:58 +0100
+Subject: [PATCH 1/3] 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(+)
+
+diff --git a/drivers/gpu/drm/vc4/vc4_crtc.c b/drivers/gpu/drm/vc4/vc4_crtc.c
+index 859ac51d06f3a..c85737f2b7f73 100644
+--- a/drivers/gpu/drm/vc4/vc4_crtc.c
++++ b/drivers/gpu/drm/vc4/vc4_crtc.c
+@@ -668,6 +668,7 @@ static void vc4_crtc_atomic_disable(struct drm_crtc *crtc,
+ 	 * someone was waiting it.
+ 	 */
+ 	vc4_crtc_send_vblank(crtc);
++	msleep(20);
+ }
+
+ static void vc4_crtc_atomic_enable(struct drm_crtc *crtc,
+
+From 75c37d08890881c02a5db5ef763ef7e97f4253d3 Mon Sep 17 00:00:00 2001
+From: Dom Cobley <popcornmix@gmail.com>
+Date: Tue, 13 Aug 2024 16:13:16 +0100
+Subject: [PATCH 2/3] drm/vc4: Implement vc6_hdmi_phy_disable
+
+The body of this function was missing so we don't reset the phy
+when disabling it.
+
+Signed-off-by: Dom Cobley <popcornmix@gmail.com>
+---
+ drivers/gpu/drm/vc4/vc4_hdmi_phy.c | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+diff --git a/drivers/gpu/drm/vc4/vc4_hdmi_phy.c b/drivers/gpu/drm/vc4/vc4_hdmi_phy.c
+index 0d55627148327..f36558932f083 100644
+--- a/drivers/gpu/drm/vc4/vc4_hdmi_phy.c
++++ b/drivers/gpu/drm/vc4/vc4_hdmi_phy.c
+@@ -1197,4 +1197,9 @@ void vc6_hdmi_phy_init(struct vc4_hdmi *vc4_hdmi,
+
+ void vc6_hdmi_phy_disable(struct vc4_hdmi *vc4_hdmi)
+ {
++	unsigned long flags;
++
++	spin_lock_irqsave(&vc4_hdmi->hw_lock, flags);
++	vc6_hdmi_reset_phy(vc4_hdmi);
++	spin_unlock_irqrestore(&vc4_hdmi->hw_lock, flags);
+ }
+
+From 1360bf475f7a12392e041bb80b20e21b677dcd4c Mon Sep 17 00:00:00 2001
+From: Dom Cobley <popcornmix@gmail.com>
+Date: Tue, 13 Aug 2024 17:18:51 +0100
+Subject: [PATCH 3/3] drm/vc4: Also power down the PLL core when resetting PHY
+
+The current reset code doesn't actually stop the hdmi output.
+That makes it difficult for displays to handle a mode set.
+
+Powering down the PLL does actually remove the hdmi signal
+and makes mode sets more reliable
+
+Signed-off-by: Dom Cobley <popcornmix@gmail.com>
+---
+ drivers/gpu/drm/vc4/vc4_hdmi_phy.c | 2 ++
+ 1 file changed, 2 insertions(+)
+
+diff --git a/drivers/gpu/drm/vc4/vc4_hdmi_phy.c b/drivers/gpu/drm/vc4/vc4_hdmi_phy.c
+index f36558932f083..83801c2684250 100644
+--- a/drivers/gpu/drm/vc4/vc4_hdmi_phy.c
++++ b/drivers/gpu/drm/vc4/vc4_hdmi_phy.c
+@@ -137,6 +137,7 @@
+ #define VC6_HDMI_TX_PHY_PLL_REFCLK_REFCLK_SEL_CMOS	BIT(13)
+ #define VC6_HDMI_TX_PHY_PLL_REFCLK_REFFRQ_MASK		VC4_MASK(9, 0)
+
++#define VC6_HDMI_TX_PHY_PLL_POST_KDIV_BYPASS_EN		BIT(4)
+ #define VC6_HDMI_TX_PHY_PLL_POST_KDIV_CLK0_SEL_MASK	VC4_MASK(3, 2)
+ #define VC6_HDMI_TX_PHY_PLL_POST_KDIV_KDIV_MASK		VC4_MASK(1, 0)
+
+@@ -947,6 +948,7 @@ static void vc6_hdmi_reset_phy(struct vc4_hdmi *vc4_hdmi)
+
+ 	HDMI_WRITE(HDMI_TX_PHY_RESET_CTL, 0);
+ 	HDMI_WRITE(HDMI_TX_PHY_POWERUP_CTL, 0);
++	HDMI_WRITE(HDMI_TX_PHY_PLL_POST_KDIV, VC6_HDMI_TX_PHY_PLL_POST_KDIV_BYPASS_EN);
+ }
+
+ void vc6_hdmi_phy_init(struct vc4_hdmi *vc4_hdmi,