On Wed, Aug 06, 2014 at 05:14:39PM -0300, Fabio Estevam wrote: > From: Fabio Estevam <fabio.estevam@xxxxxxxxxxxxx> > > This fixes a boot hang observed when the bootloader > already enabled the PCIe link for it's own use. The > fundamental problem is that Freescale forgot to wire > up the core reset, so software doesn't have a sane way > to get the core into a defined state. > > According to the DW PCIe core reference manual configuration > of the core may only happen when the LTSSM is disabled, so > this is one of the first things we do. Apparently this isn't > safe to do when the LTSSM is in any other state than > "detect" as we observe an instant machine hang when trying to > do so while the link is already up. > > As a workaround force LTSSM into detect state right before > hitting the disable switch. > > Tested on a mx6qsabresd board with PCI driver enabled in the > bootloader and also with PCI driver disabled in the bootloader. > The kernel boots succesfully on both cases now. > > Cc: <stable@xxxxxxxxxxxxxxx> # 3.16 > Signed-off-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx> > Signed-off-by: Fabio Estevam <fabio.estevam@xxxxxxxxxxxxx> I believe Lucas already had a new version of his patch. http://thread.gmane.org/gmane.linux.kernel.pci/33712/focus=33711 Shawn > --- > drivers/pci/host/pci-imx6.c | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c > index a568efa..2fa6d3a 100644 > --- a/drivers/pci/host/pci-imx6.c > +++ b/drivers/pci/host/pci-imx6.c > @@ -49,6 +49,9 @@ struct imx6_pcie { > > /* PCIe Port Logic registers (memory-mapped) */ > #define PL_OFFSET 0x700 > +#define PCIE_PL_PFLR (PL_OFFSET + 0x08) > +#define PCIE_PL_PFLR_LINK_STATE_MASK (0x3f << 16) > +#define PCIE_PL_PFLR_FORCE_LINK (1 << 15) > #define PCIE_PHY_DEBUG_R0 (PL_OFFSET + 0x28) > #define PCIE_PHY_DEBUG_R1 (PL_OFFSET + 0x2c) > #define PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING (1 << 29) > @@ -214,7 +217,19 @@ static int imx6q_pcie_abort_handler(unsigned long addr, > static int imx6_pcie_assert_core_reset(struct pcie_port *pp) > { > struct imx6_pcie *imx6_pcie = to_imx6_pcie(pp); > + u32 val; > + > + regmap_read(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12, &val); > > + if (val & IMX6Q_GPR12_PCIE_CTL_2) { > + val = readl(pp->dbi_base + PCIE_PL_PFLR); > + val &= ~PCIE_PL_PFLR_LINK_STATE_MASK; > + val |= PCIE_PL_PFLR_FORCE_LINK; > + writel(val, pp->dbi_base + PCIE_PL_PFLR); > + > + regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12, > + IMX6Q_GPR12_PCIE_CTL_2, 0 << 10); > + } > regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1, > IMX6Q_GPR1_PCIE_TEST_PD, 1 << 18); > regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1, > -- > 1.9.1 > -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html