linux-kernel - [PATCH v2 1/4] phy: zynqmp: Enable reference clock correctly

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Message-Id: <20240506170110.2874724-2-sean.anderson@linux.dev>
Date: Mon,  6 May 2024 13:01:07 -0400
From: Sean Anderson <sean.anderson@...ux.dev>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	linux-phy@...ts.infradead.org
Cc: Vinod Koul <vkoul@...nel.org>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Michal Simek <michal.simek@....com>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	Sean Anderson <sean.anderson@...ux.dev>
Subject: [PATCH v2 1/4] phy: zynqmp: Enable reference clock correctly

Lanes can use other lanes' reference clocks, as determined by refclk.
Use refclk to determine the clock to enable/disable instead of always
using the lane's own reference clock. This ensures the clock selected in
xpsgtr_configure_pll is the one enabled.

For the other half of the equation, always program REF_CLK_SEL even when
we are selecting the lane's own clock. This ensures that Linux's idea of
the reference clock matches the hardware. We use the "local" clock mux
for this instead of going through the ref clock network.

Fixes: 25d700833513 ("phy: xilinx: phy-zynqmp: dynamic clock support for power-save")
Signed-off-by: Sean Anderson <sean.anderson@...ux.dev>
---

Changes in v2:
- New

 drivers/phy/xilinx/phy-zynqmp.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/phy/xilinx/phy-zynqmp.c b/drivers/phy/xilinx/phy-zynqmp.c
index f72c5257d712..5a434382356c 100644
--- a/drivers/phy/xilinx/phy-zynqmp.c
+++ b/drivers/phy/xilinx/phy-zynqmp.c
@@ -80,7 +80,8 @@
 
 /* Reference clock selection parameters */
 #define L0_Ln_REF_CLK_SEL(n)		(0x2860 + (n) * 4)
-#define L0_REF_CLK_SEL_MASK		0x8f
+#define L0_REF_CLK_LCL_SEL		BIT(7)
+#define L0_REF_CLK_SEL_MASK		0x9f
 
 /* Calibration digital logic parameters */
 #define L3_TM_CALIB_DIG19		0xec4c
@@ -349,11 +350,14 @@ static void xpsgtr_configure_pll(struct xpsgtr_phy *gtr_phy)
 		       PLL_FREQ_MASK, ssc->pll_ref_clk);
 
 	/* Enable lane clock sharing, if required */
-	if (gtr_phy->refclk != gtr_phy->lane) {
+	if (gtr_phy->refclk == gtr_phy->lane)
+		/* Lane3 Ref Clock Selection Register */
+		xpsgtr_clr_set(gtr_phy->dev, L0_Ln_REF_CLK_SEL(gtr_phy->lane),
+			       L0_REF_CLK_SEL_MASK, L0_REF_CLK_LCL_SEL);
+	else
 		/* Lane3 Ref Clock Selection Register */
 		xpsgtr_clr_set(gtr_phy->dev, L0_Ln_REF_CLK_SEL(gtr_phy->lane),
 			       L0_REF_CLK_SEL_MASK, 1 << gtr_phy->refclk);
-	}
 
 	/* SSC step size [7:0] */
 	xpsgtr_clr_set_phy(gtr_phy, L0_PLL_SS_STEP_SIZE_0_LSB,
@@ -573,7 +577,7 @@ static int xpsgtr_phy_init(struct phy *phy)
 	mutex_lock(&gtr_dev->gtr_mutex);
 
 	/* Configure and enable the clock when peripheral phy_init call */
-	if (clk_prepare_enable(gtr_dev->clk[gtr_phy->lane]))
+	if (clk_prepare_enable(gtr_dev->clk[gtr_phy->refclk]))
 		goto out;
 
 	/* Skip initialization if not required. */
@@ -625,7 +629,7 @@ static int xpsgtr_phy_exit(struct phy *phy)
 	gtr_phy->skip_phy_init = false;
 
 	/* Ensure that disable clock only, which configure for lane */
-	clk_disable_unprepare(gtr_dev->clk[gtr_phy->lane]);
+	clk_disable_unprepare(gtr_dev->clk[gtr_phy->refclk]);
 
 	return 0;
 }
-- 
2.35.1.1320.gc452695387.dirty