soc/mediatek: dsi: reduce the hbp and hfp for phy timing

The extra data transfer in DSI, namely, lpx, hs_prepare, hs_zero,
hs_exit and the sof/eof of DSI packets, will enlarge the line time,
which causes the real frame on dsi bus to be lower than the one
calculated by video timing. Therefore, hfp_byte is reduced by d_phy to
compensate the increase in time by the extra data transfer. However, if
hfp_byte is not large enough, the hsync period will be increased on DSI
data, leading to display scrolling in firmware screen.

To avoid this situation, this patch changes the DSI Tx driver to reduce
both hfp_byte and hbp_byte, with the amount proportional to hfp and hbp,
respectively. Refer to kernel's change in CL:1915442.

Also rename 'phy_timing' to 'timing' to sync with kernel upstream.

Since the phy timing initialization sequence has been corrected, the m
value adjustment in the analogix driver can be removed.

BUG=b:144824303
BRANCH=kukui
TEST=emerge-jacuzzi coreboot
TEST=Boots and sees firmware screen on krane and juniper
TEST=No scrolling issue on juniper AUO and InnoLux panels

Change-Id: I10a4d8a4fb41c309fa1917cf1cdf19dabed98227
Signed-off-by: Yu-Ping Wu <yupingso@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38400
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/drivers/analogix/anx7625/anx7625.c b/src/drivers/analogix/anx7625/anx7625.c
index 293cc1c20e..9387a83bd9 100644
--- a/src/drivers/analogix/anx7625/anx7625.c
+++ b/src/drivers/analogix/anx7625/anx7625.c
@@ -273,7 +273,7 @@ static int anx7625_calculate_m_n(u32 pixelclock,
 		return 1;
 	}
 
-	*m = (unsigned long long)pixelclock * 599 / 600;
+	*m = pixelclock;
 	*n = XTAL_FRQ / post_divider;
 	*pd = post_divider;