Hi Raymond, It seems that there is already a similar patch [1] from Tim floating on the list.
Shawn [1] http://www.spinics.net/lists/linux-pci/msg33520.html On Mon, Sep 08, 2014 at 11:10:37AM +0200, Raymond van der Rots wrote: > Hi, > > The imx6dl on our hardware board frequently had problems bringing up the PCI > link, with or without peripherals connected. I found these issues to be due > to the initialisation order of the PCI Host. > > The host driver first enables the phy, and then enables its clocks. However, > according to the reference manual (IMX6SDLRM, page 2033): > > The phy_ref_ssp_en signal must remain deasserted until the reference clock > > is running at the appropriate frequency, at which point phy_ref_ssp_en can > > be asserted. > > > Which implies that the clocks should be brought up first, after which the > peripheral should be enabled. > This patch changes that initialisation order. > > I do not have other hardware with an imx6dl, so this patch has only been > tested on our board. Could someone confirm that this is more technically > correct or improves behaviour? > > Signed-off-by: Raymond van der Rots <raym...@electrocompaniet.no> > --- > diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c > index a568efa..17c35b4 100644 > --- a/drivers/pci/host/pci-imx6.c > +++ b/drivers/pci/host/pci-imx6.c > @@ -228,11 +228,6 @@ 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"); > @@ -254,6 +249,11 @@ static int imx6_pcie_deassert_core_reset(struct > pcie_port *pp) > /* allow the clocks to stabilize */ > usleep_range(200, 500); > > + 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); > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
