linux-kernel - [PATCH v2 2/2] phy: cadence: cdns-dphy: Update calibration wait time for startup state machine

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Message-ID: <20250326152320.3835249-3-devarsht@ti.com>
Date: Wed, 26 Mar 2025 20:53:20 +0530
From: Devarsh Thakkar <devarsht@...com>
To: <vkoul@...nel.org>, <kishon@...nel.org>, <mripard@...nel.org>,
        <linux-phy@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
CC: <sakari.ailus@...ux.intel.com>, <u.kleine-koenig@...libre.com>,
        <vigneshr@...com>, <aradhya.bhatia@...ux.dev>, <s-jain1@...com>,
        <r-donadkar@...com>, <tomi.valkeinen@...asonboard.com>
Subject: [PATCH v2 2/2] phy: cadence: cdns-dphy: Update calibration wait time for startup state machine

Use system characterized reset value specified in TRM [1] to program
calibration wait time which defines number of cycles to wait for after
startup state machine is in bandgap enable state.

This fixes PLL lock timeout error faced while using RPi DSI Panel on TI's
AM62L and J721E SoC [2].

[1] AM62P TRM (Section ):
https://www.ti.com/lit/pdf/spruj83

[2]:
Link: https://gist.github.com/devarsht/89e4830e886774fcd50aa6e29cce3a79

Cc: stable@...r.kernel.org
Fixes: 7a343c8bf4b5 ("phy: Add Cadence D-PHY support")
Signed-off-by: Devarsh Thakkar <devarsht@...com>
---
V2: Introduced this as as separate patch

 drivers/phy/cadence/cdns-dphy.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/phy/cadence/cdns-dphy.c b/drivers/phy/cadence/cdns-dphy.c
index c4de9e4d3e93..11fbffe5aafd 100644
--- a/drivers/phy/cadence/cdns-dphy.c
+++ b/drivers/phy/cadence/cdns-dphy.c
@@ -30,6 +30,7 @@
 
 #define DPHY_CMN_SSM			DPHY_PMA_CMN(0x20)
 #define DPHY_CMN_SSM_EN			BIT(0)
+#define DPHY_CMN_SSM_CAL_WAIT_TIME	GENMASK(8, 1)
 #define DPHY_CMN_TX_MODE_EN		BIT(9)
 
 #define DPHY_CMN_PWM			DPHY_PMA_CMN(0x40)
@@ -405,6 +406,8 @@ static int cdns_dphy_configure(struct phy *phy, union phy_configure_opts *opts)
 	reg = FIELD_PREP(DPHY_BAND_CFG_LEFT_BAND, band_ctrl) |
 	      FIELD_PREP(DPHY_BAND_CFG_RIGHT_BAND, band_ctrl);
 	writel(reg, dphy->regs + DPHY_BAND_CFG);
+	writel(FIELD_PREP(DPHY_CMN_SSM_CAL_WAIT_TIME, 0x14) | DPHY_CMN_SSM_EN | DPHY_CMN_TX_MODE_EN,
+	       dphy->regs + DPHY_CMN_SSM);
 
 	ret = cdns_dphy_wait_for_pll_lock(dphy);
 	if (ret)
-- 
2.39.1