linux-kernel - [PATCH V2 3/3] phy: freescale: fsl-samsung-hdmi: Clean up fld_tg

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Message-ID: <20241026132014.73050-3-aford173@gmail.com>
Date: Sat, 26 Oct 2024 08:19:59 -0500
From: Adam Ford <aford173@...il.com>
To: linux-phy@...ts.infradead.org
Cc: aford@...conembedded.com,
	sandor.yu@....com,
	Adam Ford <aford173@...il.com>,
	Frieder Schrempf <frieder.schrempf@...tron.de>,
	Vinod Koul <vkoul@...nel.org>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	Dominique Martinet <dominique.martinet@...ark-techno.com>,
	Marco Felsch <m.felsch@...gutronix.de>,
	Uwe Kleine-König <u.kleine-koenig@...libre.com>,
	Lucas Stach <l.stach@...gutronix.de>,
	linux-kernel@...r.kernel.org
Subject: [PATCH V2 3/3] phy: freescale: fsl-samsung-hdmi: Clean up fld_tg_code calculation

Currently, the calcuation for fld_tg_code is based on a lookup table,
but there are gaps in the lookup table, and frequencies in these
gaps may not properly use the correct divider.  Based on the description
of FLD_CK_DIV, the internal PLL frequency should be less than 50 MHz,
so directly calcuate the value of FLD_CK_DIV from pixclk.
This allow for proper calcuation of any pixel clock and eliminates a
few gaps in the LUT.

Since the value of the int_pllclk is in Hz, do the fixed-point
math in Hz to achieve a more accurate value and reduces the complexity
of the caluation to 24MHz * (256 / int_pllclk).

Fixes: 6ad082bee902 ("phy: freescale: add Samsung HDMI PHY")
Signed-off-by: Adam Ford <aford173@...il.com>
Reviewed-by: Frieder Schrempf <frieder.schrempf@...tron.de>
---
V2:  No change

diff --git a/drivers/phy/freescale/phy-fsl-samsung-hdmi.c b/drivers/phy/freescale/phy-fsl-samsung-hdmi.c
index 121f67455cec..5eac70a1e858 100644
--- a/drivers/phy/freescale/phy-fsl-samsung-hdmi.c
+++ b/drivers/phy/freescale/phy-fsl-samsung-hdmi.c
@@ -331,25 +331,17 @@ fsl_samsung_hdmi_phy_configure_pll_lock_det(struct fsl_samsung_hdmi_phy *phy,
 {
 	u32 pclk = cfg->pixclk;
 	u32 fld_tg_code;
-	u32 pclk_khz;
-	u8 div = 1;
-
-	switch (cfg->pixclk) {
-	case  22250000 ...  47500000:
-		div = 1;
-		break;
-	case  50349650 ...  99000000:
-		div = 2;
-		break;
-	case 100699300 ... 198000000:
-		div = 4;
-		break;
-	case 205000000 ... 297000000:
-		div = 8;
-		break;
+	u32 int_pllclk;
+	u8 div;
+
+	/* Find int_pllclk speed */
+	for (div = 0; div < 4; div++) {
+		int_pllclk = pclk / (1 << div);
+		if (int_pllclk < (50 * MHZ))
+			break;
 	}
 
-	writeb(FIELD_PREP(REG12_CK_DIV_MASK, ilog2(div)), phy->regs + PHY_REG(12));
+	writeb(FIELD_PREP(REG12_CK_DIV_MASK, div), phy->regs + PHY_REG(12));
 
 	/*
 	 * Calculation for the frequency lock detector target code (fld_tg_code)
@@ -362,10 +354,8 @@ fsl_samsung_hdmi_phy_configure_pll_lock_det(struct fsl_samsung_hdmi_phy *phy,
 	 *        settings rounding up always too. TODO: Check if that is
 	 *        correct.
 	 */
-	pclk /= div;
-	pclk_khz = pclk / 1000;
-	fld_tg_code = 256 * 1000 * 1000 / pclk_khz * 24;
-	fld_tg_code = DIV_ROUND_UP(fld_tg_code, 1000);
+
+	fld_tg_code =  DIV_ROUND_UP(24 * MHZ * 256, int_pllclk);
 
 	/* FLD_TOL and FLD_RP_CODE taken from downstream driver */
 	writeb(FIELD_PREP(REG13_TG_CODE_LOW_MASK, fld_tg_code),
-- 
2.45.2