From 9da2d153eb010d3e92083c322e87de9ae066d93e Mon Sep 17 00:00:00 2001 From: popcornmix 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 --- 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;