[PATCH] phy: freescale: imx8m-pcie: assert phy reset during power on

[Rafael Beims <rafael@beims.me>]

From: Rafael Beims <rafael.beims@toradex.com>

After U-Boot initializes PCIe with "pcie enum", Linux fails to detect
an NVMe disk on some boot cycles with:

  phy phy-32f00000.pcie-phy.0: phy poweron failed --> -110

Discussion with NXP identified that the iMX8MP PCIe PHY PLL may fail to
lock when re-initialized without a reset cycle [1].

The issue reproduces on 7% of tested hardware platforms, with a 30-40%
failure rate per affected device across boot cycles.

Insert a reset cycle in the power-on routine to ensure the PHY is
initialized from a known state.

[1] https://community.nxp.com/t5/i-MX-Processors/iMX8MP-PCIe-initialization-in-U-Boot/m-p/2248437#M242401

Signed-off-by: Rafael Beims <rafael.beims@toradex.com>
Cc: stable@vger.kernel.org
---
 drivers/phy/freescale/phy-fsl-imx8m-pcie.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/phy/freescale/phy-fsl-imx8m-pcie.c b/drivers/phy/freescale/phy-fsl-imx8m-pcie.c
index 68fcc8114d75..7f5600103a00 100644
--- a/drivers/phy/freescale/phy-fsl-imx8m-pcie.c
+++ b/drivers/phy/freescale/phy-fsl-imx8m-pcie.c
@@ -89,7 +89,8 @@ static int imx8_pcie_phy_power_on(struct phy *phy)
 			writel(imx8_phy->tx_deemph_gen2,
 			       imx8_phy->base + PCIE_PHY_TRSV_REG6);
 		break;
-	case IMX8MP: /* Do nothing. */
+	case IMX8MP:
+		reset_control_assert(imx8_phy->reset);
 		break;
 	}
 
-- 
2.51.0