1 files changed, 30 insertions, 0 deletions
diff --git a/target/linux/bcm27xx/patches-5.4/950-0615-vc4_hdmi_phy-Fix-offset-calculation.patch b/target/linux/bcm27xx/patches-5.4/950-0615-vc4_hdmi_phy-Fix-offset-calculation.patch
new file mode 100644
index 0000000000..83d8d25e29
--- /dev/null
+++ b/target/linux/bcm27xx/patches-5.4/950-0615-vc4_hdmi_phy-Fix-offset-calculation.patch
@@ -0,0 +1,30 @@
+From 9da2d153eb010d3e92083c322e87de9ae066d93e Mon Sep 17 00:00:00 2001
+From: popcornmix <popcornmix@gmail.com>
+Date: Thu, 2 Apr 2020 16:46:31 +0100
+Subject: [PATCH] vc4_hdmi_phy: Fix offset calculation
+
+The original firmware code worked with float and did
+   offset = ((vco_freq / fref * 2) * (1 << 22));
+   offset >>= 2;
+
+In this code it's all integer so doing the integer divide before the shift loses lots of precision
+
+This fixes the issue of 1080p59.94 mode having 59.64 fps
+
+Signed-off-by: popcornmix <popcornmix@gmail.com>
+---
+ drivers/gpu/drm/vc4/vc4_hdmi_phy.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/drivers/gpu/drm/vc4/vc4_hdmi_phy.c
++++ b/drivers/gpu/drm/vc4/vc4_hdmi_phy.c
+@@ -192,8 +192,8 @@ static u32 phy_get_rm_offset(unsigned lo
+ 
+ 	/* RM offset is stored as 9.22 format */
+ 	offset = vco_freq * 2;
+-	do_div(offset, fref);
+ 	offset = offset << 22;
++	do_div(offset, fref);
+ 	offset >>= 2;
+ 
+ 	return offset;