RK356x hdmi doesn't support resolutions up to 4k at 60Hz

[Sascha Hauer]

On Tue, Oct 10, 2023 at 11:15:22AM +0800, Doug Brewer wrote:
> Hi,
> 
> I tested the Linux kernel 6.5.6 on Rock 3A, the hdmi doesn't support
> resolutions up to 4k at 60Hz.  4k at 30Hz works for me.
> Any idea how to fix it?  Thanks.
> 

Yes, 4k at 60 is not yet working. In principle all that's missing should be
the patch below. However, it didn't work for me the time I tested it, so
I haven't tried upstreaming it.

Sascha

--------------------------------8<-------------------------------

>From 069ce874a58dbd164825207377c421837de0f0e8 Mon Sep 17 00:00:00 2001
From: Sascha Hauer <s.hauer at pengutronix.de>
Date: Mon, 23 Jan 2023 12:37:32 +0100
Subject: [PATCH] drm/rockchip: dw_hdmi: Add support for 4k at 60 resolution

Does not work yet on our Samsung monitor, it looses synchronization
every now and then.

Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
index 725952811752b..ef219cc6e1cdd 100644
--- a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
@@ -168,6 +168,12 @@ static const struct dw_hdmi_mpll_config rockchip_mpll_cfg[] = {
 			{ 0x5a64, 0x0003 },
 		},
 	}, {
+		600000000, {
+			{ 0x1a40, 0x0003 },
+			{ 0x3b4c, 0x0003 },
+			{ 0x5a64, 0x0003 },
+		},
+	},{
 		~0UL, {
 			{ 0x00a0, 0x000a },
 			{ 0x2001, 0x000f },
@@ -204,6 +210,7 @@ static const struct dw_hdmi_phy_config rockchip_phy_config[] = {
 	{ 74250000,  0x8009, 0x0004, 0x0272},
 	{ 148500000, 0x802b, 0x0004, 0x028d},
 	{ 297000000, 0x8039, 0x0005, 0x028d},
+	{ 594000000, 0x8039, 0x0000, 0x019d},
 	{ ~0UL,	     0x0000, 0x0000, 0x0000}
 };
 
-- 
2.39.2

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