On Wednesday, February 12, 2014 at 08:27:55 AM, Sascha Hauer wrote:
+CC Troy Kisky, since I think he submitted something similar some time ago
already.
Otherwise I agree this happens.
> This is broken since:
> | commit e6daf4a5e1b813bc7f85507ec83b8c2452c121e6
> | Author: Marek Vasut <marex@xxxxxxx>
> | Date: Thu Dec 12 22:49:59 2013 +0100
> |
> | PCI: imx6: Report "link up" only after link training completes
> |
> | While waiting for the PHY to report the PCIe link is up, we might hit
> | a situation where the link training is still in progress, while the
> | PHY already reports the link is up. Add additional check for this
> | condition.
> |
> | Signed-off-by: Marek Vasut <marex@xxxxxxx>
> | Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> | Acked-by: Shawn Guo <shawn.guo@xxxxxxxxxx>
>
> The problem is: Before the above commit only the
> PCIE_PHY_DEBUG_R1_XMLH_LINK_UP bit was used to determine whether the link
> is up or not. Since the above commit also the
> PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING is used. This means a link still
> being trained is as link down.
> The designware driver changes the PORT_LOGIC_SPEED_CHANGE bit in
> dw_pcie_host_init() which causes the link to be retrained. During the next
> call to dw_pcie_rd_conf() the link is then reported being down and the
> function returns PCIBIOS_DEVICE_NOT_FOUND resulting in nonfunctioning
> PCIe.
>
> This patch fixes this by waiting until the link training has finished
> before testing the PCIE_PHY_DEBUG_R1_XMLH_LINK_UP bit. This is hardly the
> correct solution, but I don't know what should be done instead.
>
> Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> Cc: Richard Zhu <r65037@xxxxxxxxxxxxx> (maintainer:PCI DRIVER FOR IMX6)
> Cc: Shawn Guo <shawn.guo@xxxxxxxxxx> (maintainer:PCI DRIVER FOR IMX6)
> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> (supporter:PCI SUBSYSTEM)
> Cc: linux-pci@xxxxxxxxxxxxxxx
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Cc: Marek Vasut <marex@xxxxxxx>
> ---
> drivers/pci/host/pci-imx6.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
> index 866bdc7..9b6b501 100644
> --- a/drivers/pci/host/pci-imx6.c
> +++ b/drivers/pci/host/pci-imx6.c
> @@ -449,6 +449,7 @@ static void imx6_pcie_reset_phy(struct pcie_port *pp)
> static int imx6_pcie_link_up(struct pcie_port *pp)
> {
> u32 rc, ltssm, rx_valid;
> + int count = 1000;
>
> /*
> * Test if the PHY reports that the link is up and also that
> @@ -458,8 +459,13 @@ static int imx6_pcie_link_up(struct pcie_port *pp)
> * as well here.
> */
> rc = readl(pp->dbi_base + PCIE_PHY_DEBUG_R1);
> - if ((rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_UP) &&
> - !(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING))
> + while (rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING) {
> + if (!count--)
> + return 0;
> + rc = readl(pp->dbi_base + PCIE_PHY_DEBUG_R1);
> + }
> +
> + if (rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_UP)
> return 1;
>
> /*
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