[PATCH v1] phy: fsl-imx8mq-usb: Fix PCS_TX_SWING_FULL register configuration

From: Stefano Radaelli <stefano.radaelli21@gmail.com>
To: vkoul@kernel.org, neil.armstrong@linaro.org, shawnguo@kernel.org,
	s.hauer@pengutronix.de, kernel@pengutronix.de,
	festevam@gmail.com, j.zink@pengutronix.de,
	linux-kernel@vger.kernel.org
Cc: xu.yang_2@nxp.com, jun.li@nxp.com, Frank.Li@nxp.com,
	haibo.chen@nxp.com, linux-phy@lists.infradead.org,
	imx@lists.linux.dev, Stefano Radaelli <stefano.r@variscite.com>,
	Pierluigi Passaro <pierluigi.p@variscite.com>
Subject: [PATCH v1] phy: fsl-imx8mq-usb: Fix PCS_TX_SWING_FULL register configuration
Date: Thu, 18 Dec 2025 18:49:20 +0100	[thread overview]
Message-ID: <20251218174920.359282-1-stefano.r@variscite.com> (raw)

Clear the PCS_TX_SWING_FULL field mask before setting the new value
in PHY_CTRL5 register. Without clearing the mask first, the OR operation
could leave previously set bits, resulting in incorrect
register configuration.

Fixes: 63c85ad0cd81 ("phy: fsl-imx8mp-usb: add support for phy tuning")
Suggested-by: Pierluigi Passaro <pierluigi.p@variscite.com>
Signed-off-by: Stefano Radaelli <stefano.r@variscite.com>
---
 drivers/phy/freescale/phy-fsl-imx8mq-usb.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/phy/freescale/phy-fsl-imx8mq-usb.c b/drivers/phy/freescale/phy-fsl-imx8mq-usb.c
index ad8a55012e42..9458b6e5fcf4 100644
--- a/drivers/phy/freescale/phy-fsl-imx8mq-usb.c
+++ b/drivers/phy/freescale/phy-fsl-imx8mq-usb.c
@@ -504,6 +504,7 @@ static void imx8m_phy_tune(struct imx8mq_usb_phy *imx_phy)
 
 	if (imx_phy->pcs_tx_swing_full != PHY_TUNE_DEFAULT) {
 		value = readl(imx_phy->base + PHY_CTRL5);
+		value &= ~PHY_CTRL5_PCS_TX_SWING_FULL_MASK;
 		value |= FIELD_PREP(PHY_CTRL5_PCS_TX_SWING_FULL_MASK,
 				   imx_phy->pcs_tx_swing_full);
 		writel(value, imx_phy->base + PHY_CTRL5);

base-commit: ea1013c1539270e372fc99854bc6e4d94eaeff66
-- 
2.47.3


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