linux-kernel - [PATCH AUTOSEL 6.14 03/44] drm/rockchip: Don't change hdmi reference clock rate

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Message-Id: <20250403191313.2679091-3-sashal@kernel.org>
Date: Thu,  3 Apr 2025 15:12:32 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Derek Foreman <derek.foreman@...labora.com>,
	Cristian Ciocaltea <cristian.ciocaltea@...labora.com>,
	Heiko Stuebner <heiko@...ech.de>,
	Sasha Levin <sashal@...nel.org>,
	hjc@...k-chips.com,
	andy.yan@...k-chips.com,
	maarten.lankhorst@...ux.intel.com,
	mripard@...nel.org,
	tzimmermann@...e.de,
	airlied@...il.com,
	simona@...ll.ch,
	dri-devel@...ts.freedesktop.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-rockchip@...ts.infradead.org
Subject: [PATCH AUTOSEL 6.14 03/44] drm/rockchip: Don't change hdmi reference clock rate

From: Derek Foreman <derek.foreman@...labora.com>

[ Upstream commit 1854df7087be70ad54e24b2e308d7558ebea9f27 ]

The code that changes hdmi->ref_clk was accidentally copied from
downstream code that sets a different clock. We don't actually
want to set any clock here at all.

Setting this clock incorrectly leads to incorrect timings for
DDC, CEC, and HDCP signal generation.

No Fixes listed, as the theoretical timing error in DDC appears to
still be within tolerances and harmless - and HDCP and CEC are not
yet supported.

Signed-off-by: Derek Foreman <derek.foreman@...labora.com>
Reviewed-by: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
Signed-off-by: Heiko Stuebner <heiko@...ech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20241217201708.3320673-1-derek.foreman@collabora.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 13 -------------
 1 file changed, 13 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
index e498767a0a667..cebd72bf1ef25 100644
--- a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
@@ -54,7 +54,6 @@ struct rockchip_hdmi_qp {
 	struct regmap *regmap;
 	struct regmap *vo_regmap;
 	struct rockchip_encoder encoder;
-	struct clk *ref_clk;
 	struct dw_hdmi_qp *hdmi;
 	struct phy *phy;
 	struct gpio_desc *enable_gpio;
@@ -81,7 +80,6 @@ static void dw_hdmi_qp_rockchip_encoder_enable(struct drm_encoder *encoder)
 	if (crtc && crtc->state) {
 		rate = drm_hdmi_compute_mode_clock(&crtc->state->adjusted_mode,
 						   8, HDMI_COLORSPACE_RGB);
-		clk_set_rate(hdmi->ref_clk, rate);
 		/*
 		 * FIXME: Temporary workaround to pass pixel clock rate
 		 * to the PHY driver until phy_configure_opts_hdmi
@@ -330,17 +328,6 @@ static int dw_hdmi_qp_rockchip_bind(struct device *dev, struct device *master,
 		return ret;
 	}
 
-	for (i = 0; i < ret; i++) {
-		if (!strcmp(clks[i].id, "ref")) {
-			hdmi->ref_clk = clks[1].clk;
-			break;
-		}
-	}
-	if (!hdmi->ref_clk) {
-		drm_err(hdmi, "Missing ref clock\n");
-		return -EINVAL;
-	}
-
 	hdmi->enable_gpio = devm_gpiod_get_optional(hdmi->dev, "enable",
 						    GPIOD_OUT_HIGH);
 	if (IS_ERR(hdmi->enable_gpio)) {
-- 
2.39.5