linux-kernel - [PATCH v2 02/14] phy: rockchip: samsung-hdptx: Fix reported clock rate in high bpc mode

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Message-Id: <20250805-phy-hdptx-frl-v2-2-d118bd4b6e0b@collabora.com>
Date: Tue, 05 Aug 2025 14:56:44 +0300
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>, Algea Cao <algea.cao@...k-chips.com>, 
 Dmitry Baryshkov <lumag@...nel.org>
Cc: kernel@...labora.com, linux-phy@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 linux-rockchip@...ts.infradead.org, Andy Yan <andy.yan@...k-chips.com>
Subject: [PATCH v2 02/14] 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 79db57ee90d1487b51f4ddadde870a275dd7b17b..8adf6e84fc0b762a7a6042459601c3271572de8e 100644
--- a/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
+++ b/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
@@ -1038,7 +1038,8 @@ 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;
 }
@@ -1896,19 +1897,20 @@ 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;
 	}
 
 	/*

-- 
2.50.0