linux-kernel - [PATCH RESEND 1/3] phy: rockchip: samsung-hdptx: Fix reported clock rate in high bpc mode

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Message-Id: <20251028-phy-hdptx-fixes-v1-1-ecc642a59d94@collabora.com>
Date: Tue, 28 Oct 2025 10:00:54 +0200
From: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
To: Vinod Koul <vkoul@...nel.org>, 
 Kishon Vijay Abraham I <kishon@...nel.org>, 
 Heiko Stuebner <heiko@...ech.de>, Dmitry Baryshkov <lumag@...nel.org>, 
 Algea Cao <algea.cao@...k-chips.com>
Cc: kernel@...labora.com, linux-phy@...ts.infradead.org, 
 linux-arm-kernel@...ts.infradead.org, linux-rockchip@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, Andy Yan <andy.yan@...k-chips.com>
Subject: [PATCH RESEND 1/3] phy: rockchip: samsung-hdptx: Fix reported
 clock rate in high bpc mode

When making use of the clock provider functionality, the output clock
does normally match the TMDS character rate, which is what the PHY PLL
gets configured to.

However, this is only applicable for default color depth of 8 bpc.  For
higher depths, the output clock is further divided by the hardware
according to the formula:

  output_clock_rate = tmds_char_rate * 8 / bpc

Since the existence of the clock divider wasn't taken into account when
support for high bpc has been introduced, make the necessary adjustments
to report the correct clock rate.

Fixes: 9d0ec51d7c22 ("phy: rockchip: samsung-hdptx: Add high color depth management")
Reported-by: Andy Yan <andy.yan@...k-chips.com>
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
---
 drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c b/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
index 01bbf668e05e..aee03e8655f6 100644
--- a/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
+++ b/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
@@ -1037,7 +1037,8 @@ static int rk_hdptx_ropll_tmds_cmn_config(struct rk_hdptx_phy *hdptx)
 
 	ret = rk_hdptx_post_enable_pll(hdptx);
 	if (!ret)
-		hdptx->hw_rate = hdptx->hdmi_cfg.tmds_char_rate;
+		hdptx->hw_rate = DIV_ROUND_CLOSEST_ULL(hdptx->hdmi_cfg.tmds_char_rate * 8,
+						       hdptx->hdmi_cfg.bpc);
 
 	return ret;
 }
@@ -1895,19 +1896,20 @@ static long rk_hdptx_phy_clk_round_rate(struct clk_hw *hw, unsigned long rate,
 	 * hence ensure rk_hdptx_phy_clk_set_rate() won't be invoked with
 	 * a different rate argument.
 	 */
-	return hdptx->hdmi_cfg.tmds_char_rate;
+	return DIV_ROUND_CLOSEST_ULL(hdptx->hdmi_cfg.tmds_char_rate * 8, hdptx->hdmi_cfg.bpc);
 }
 
 static int rk_hdptx_phy_clk_set_rate(struct clk_hw *hw, unsigned long rate,
 				     unsigned long parent_rate)
 {
 	struct rk_hdptx_phy *hdptx = to_rk_hdptx_phy(hw);
+	unsigned long long tmds_rate = DIV_ROUND_CLOSEST_ULL(rate * hdptx->hdmi_cfg.bpc, 8);
 
 	/* Revert any unlikely TMDS char rate change since round_rate() */
-	if (hdptx->hdmi_cfg.tmds_char_rate != rate) {
-		dev_warn(hdptx->dev, "Reverting unexpected rate change from %lu to %llu\n",
-			 rate, hdptx->hdmi_cfg.tmds_char_rate);
-		hdptx->hdmi_cfg.tmds_char_rate = rate;
+	if (hdptx->hdmi_cfg.tmds_char_rate != tmds_rate) {
+		dev_warn(hdptx->dev, "Reverting unexpected rate change from %llu to %llu\n",
+			 tmds_rate, hdptx->hdmi_cfg.tmds_char_rate);
+		hdptx->hdmi_cfg.tmds_char_rate = tmds_rate;
 	}
 
 	/*

-- 
2.51.0