[PATCH 6.19 564/781] phy: rockchip: samsung-hdptx: Pre-compute HDMI PLL config for 461.10125 MHz output

Greg Kroah-Hartman
2026-02-25T01:37:28Z

From: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>

[ Upstream commit f2daf0c67a1767ff6536aa3e96599afb42ca42e7 ]

Attempting to make use of a 1080p@120Hz display mode with 10 bpc RGB on
my Acer XV275K P3 monitor results in a blank image. A similar behavior
has been reported on Philips 279M1RV.

The faulty modeline is created by drm_gtf_mode_complex() based on the
following EDID entry from the Standard Timings block:

GTF: 1920x1080 119.999987 Hz 16:9 138.840 kHz 368.759000 MHz

It's worth noting the computed pixel clock ends up being slightly higher
at 368.881000 MHz. Nevertheless, this seems to work consistently fine
with 8 bpc RGB.

After switching to 10 bpc, the TMDS character rate expected for the mode
increases to 461.101250 MHz, as per drm_hdmi_compute_mode_clock().

Since there is no entry for this rate in the ropll_tmds_cfg table, the
necessary HDMI PLL configuration parameters are calculated dynamically
by rk_hdptx_phy_clk_pll_calc(). However, the resulting output rate is
not quite a perfect match, i.e. 461.100000 MHz. That proved to be the
actual root cause of the problem.

Add a new entry to the TMDS configuration table and provide the
necessary frequency division coefficients for the PHY PLL to generate
the expected 461.101250 MHz output.

Fixes: 9d0ec51d7c22 ("phy: rockchip: samsung-hdptx: Add high color depth management")
Tested-by: Derek Foreman <derek.foreman@collabora.com>
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Link: https://patch.msgid.link/20251221-phy-hdptx-pll-fix-v2-1-ae4abf7f75a1@collabora.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c b/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
index 29de2f7bdae8a..cafa618d70fdc 100644
--- a/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
+++ b/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
@@ -414,6 +414,8 @@ struct rk_hdptx_phy {
static const struct ropll_config ropll_tmds_cfg[] = {
{ 594000000ULL, 124, 124, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 62, 1, 16, 5, 0,
1, 1, 0, 0x20, 0x0c, 1, 0x0e, 0, 0, },
+ { 461101250ULL, 97, 97, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 71, 1, 53, 2, 6,
+ 35, 1, 0, 0x20, 0x0c, 1, 0x0e, 0, 0, },
{ 371250000ULL, 155, 155, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 62, 1, 16, 5, 0,
1, 1, 0, 0x20, 0x0c, 1, 0x0e, 0, 0, },
{ 297000000ULL, 124, 124, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 62, 1, 16, 5, 0,
--
2.51.0