From 3fce0e882f61513c45c67e15bd0fde03341b58a5 Mon Sep 17 00:00:00 2001 From: Tim Harvey Date: Thu, 7 Aug 2014 23:36:40 -0700 Subject: 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 Signed-off-by: Tim Harvey Signed-off-by: Bjorn Helgaas Acked-by: Marek Vasut Acked-by: Lucas Stach --- drivers/pci/host/pci-imx6.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) (limited to 'drivers/pci/host') diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c index b5988b4e56e5..233fe8a88264 100644 --- a/drivers/pci/host/pci-imx6.c +++ b/drivers/pci/host/pci-imx6.c @@ -257,11 +257,6 @@ static int imx6_pcie_deassert_core_reset(struct pcie_port *pp) 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 @@ static int imx6_pcie_deassert_core_reset(struct pcie_port *pp) /* 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); -- cgit v1.2.3-59-g8ed1b