[PATCH v8 07/11] PCI: imx6: Improve comment for workaround ERR010728

[Frank Li]

Improve comment about workaround ERR010728 by using official errata
document content(https://www.nxp.com/webapp/Download?colCode=IMX7DS_2N09P).

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam at linaro.org>
Signed-off-by: Frank Li <Frank.Li at nxp.com>
---
 drivers/pci/controller/dwc/pci-imx6.c | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index e295c7bef732e..6be32a93411b6 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -712,9 +712,26 @@ static int imx7d_pcie_core_reset(struct imx_pcie *imx_pcie, bool assert)
 		return 0;
 
 	/*
-	 * Workaround for ERR010728, failure of PCI-e PLL VCO to
-	 * oscillate, especially when cold. This turns off "Duty-cycle
-	 * Corrector" and other mysterious undocumented things.
+	 * Workaround for ERR010728 (IMX7DS_2N09P, Rev. 1.1, 4/2023):
+	 *
+	 * PCIe: PLL may fail to lock under corner conditions.
+	 *
+	 * Initial VCO oscillation may fail under corner conditions such as
+	 * cold temperature which will cause the PCIe PLL fail to lock in the
+	 * initialization phase.
+	 *
+	 * The Duty-cycle Corrector calibration must be disabled.
+	 *
+	 * 1. De-assert the G_RST signal by clearing
+	 *    SRC_PCIEPHY_RCR[PCIEPHY_G_RST].
+	 * 2. De-assert DCC_FB_EN by writing data “0x29” to the register
+	 *    address 0x306d0014 (PCIE_PHY_CMN_REG4).
+	 * 3. Assert RX_EQS, RX_EQ_SEL by writing data “0x48” to the register
+	 *    address 0x306d0090 (PCIE_PHY_CMN_REG24).
+	 * 4. Assert ATT_MODE by writing data “0xbc” to the register
+	 *    address 0x306d0098 (PCIE_PHY_CMN_REG26).
+	 * 5. De-assert the CMN_RST signal by clearing register bit
+	 *    SRC_PCIEPHY_RCR[PCIEPHY_BTN]
 	 */
 
 	if (likely(imx_pcie->phy_base)) {

-- 
2.34.1