linux-kernel - [PATCH] clk: rs9: fix wrong default value for clock amplitude

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Date: Mon, 15 Apr 2024 14:42:19 +0200
From: Catalin Popescu <catalin.popescu@...ca-geosystems.com>
To: marex@...x.de,
	sboyd@...nel.org,
	mturquette@...libre.com,
	biju.das.jz@...renesas.com,
	marek.vasut+renesas@...lbox.org
Cc: linux-clk@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	bsp-development.geo@...ca-geosystems.com,
	m.felsch@...gutronix.de,
	Catalin Popescu <catalin.popescu@...ca-geosystems.com>
Subject: [PATCH] clk: rs9: fix wrong default value for clock amplitude

According to 9FGV0241, 9FGV0441 & 9FGV0841 datasheets, the default
value for the clock amplitude is 0.8V, while the driver assumes 0.7V.

Additionally, define constants for default values for both clock
amplitude and spread spectrum and use them.

Fixes: 892e0ddea1aa ("clk: rs9: Add Renesas 9-series PCIe clock generator driver")

Signed-off-by: Catalin Popescu <catalin.popescu@...ca-geosystems.com>
---
Changes in v2:
 - update commit message with "9FGV0841", document change about spread
   spectrum and add Fixes tag.
---
 drivers/clk/clk-renesas-pcie.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/clk-renesas-pcie.c b/drivers/clk/clk-renesas-pcie.c
index 53e21ac302e6..4c3a5e4eb77a 100644
--- a/drivers/clk/clk-renesas-pcie.c
+++ b/drivers/clk/clk-renesas-pcie.c
@@ -25,10 +25,12 @@
 #define RS9_REG_SS_AMP_0V7			0x1
 #define RS9_REG_SS_AMP_0V8			0x2
 #define RS9_REG_SS_AMP_0V9			0x3
+#define RS9_REG_SS_AMP_DEFAULT			RS9_REG_SS_AMP_0V8
 #define RS9_REG_SS_AMP_MASK			0x3
 #define RS9_REG_SS_SSC_100			0
 #define RS9_REG_SS_SSC_M025			(1 << 3)
 #define RS9_REG_SS_SSC_M050			(3 << 3)
+#define RS9_REG_SS_SSC_DEFAULT			RS9_REG_SS_SSC_100
 #define RS9_REG_SS_SSC_MASK			(3 << 3)
 #define RS9_REG_SS_SSC_LOCK			BIT(5)
 #define RS9_REG_SR				0x2
@@ -205,8 +207,8 @@ static int rs9_get_common_config(struct rs9_driver_data *rs9)
 	int ret;
 
 	/* Set defaults */
-	rs9->pll_amplitude = RS9_REG_SS_AMP_0V7;
-	rs9->pll_ssc = RS9_REG_SS_SSC_100;
+	rs9->pll_amplitude = RS9_REG_SS_AMP_DEFAULT;
+	rs9->pll_ssc = RS9_REG_SS_SSC_DEFAULT;
 
 	/* Output clock amplitude */
 	ret = of_property_read_u32(np, "renesas,out-amplitude-microvolt",
@@ -247,13 +249,13 @@ static void rs9_update_config(struct rs9_driver_data *rs9)
 	int i;
 
 	/* If amplitude is non-default, update it. */
-	if (rs9->pll_amplitude != RS9_REG_SS_AMP_0V7) {
+	if (rs9->pll_amplitude != RS9_REG_SS_AMP_DEFAULT) {
 		regmap_update_bits(rs9->regmap, RS9_REG_SS, RS9_REG_SS_AMP_MASK,
 				   rs9->pll_amplitude);
 	}
 
 	/* If SSC is non-default, update it. */
-	if (rs9->pll_ssc != RS9_REG_SS_SSC_100) {
+	if (rs9->pll_ssc != RS9_REG_SS_SSC_DEFAULT) {
 		regmap_update_bits(rs9->regmap, RS9_REG_SS, RS9_REG_SS_SSC_MASK,
 				   rs9->pll_ssc);
 	}

base-commit: 6bd343537461b57f3efe5dfc5fc193a232dfef1e
prerequisite-patch-id: 0000000000000000000000000000000000000000
-- 
2.34.1