PCI: imx6: Delay enabling reference clock for SS until it stabilizes
According to the IMX6 reference manuals, REF_SSP_EN (Reference clock enable
for SS function) must remain deasserted until the reference clock is
running at the appropriate frequency.
Delay enabling the reference clock for the SS function until it has
stabilized. This prevents a high link failure rate (>5%) on certain IMX6
boards at various temperatures.
[bhelgaas: reword changelog slightly]
Tested-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Marek Vasut <marex@denx.de>
Acked-by: Lucas Stach <l.stach@pengutronix.de>
diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
index b5988b4..233fe8a 100644
--- a/drivers/pci/host/pci-imx6.c
+++ b/drivers/pci/host/pci-imx6.c
@@ -257,11 +257,6 @@
struct imx6_pcie *imx6_pcie = to_imx6_pcie(pp);
int ret;
- regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
- IMX6Q_GPR1_PCIE_TEST_PD, 0 << 18);
- regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
- IMX6Q_GPR1_PCIE_REF_CLK_EN, 1 << 16);
-
ret = clk_prepare_enable(imx6_pcie->pcie_phy);
if (ret) {
dev_err(pp->dev, "unable to enable pcie_phy clock\n");
@@ -283,6 +278,12 @@
/* allow the clocks to stabilize */
usleep_range(200, 500);
+ /* power up core phy and enable ref clock */
+ regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
+ IMX6Q_GPR1_PCIE_TEST_PD, 0 << 18);
+ regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
+ IMX6Q_GPR1_PCIE_REF_CLK_EN, 1 << 16);
+
/* Some boards don't have PCIe reset GPIO. */
if (gpio_is_valid(imx6_pcie->reset_gpio)) {
gpio_set_value(imx6_pcie->reset_gpio, 0);