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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;
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