| Message ID | 1392841338-13527-1-git-send-email-troy.kisky@boundarydevices.com |
|---|---|
| State | Accepted |
| Headers | show |
On Wed, Feb 19, 2014 at 01:22:18PM -0700, Troy Kisky wrote: > From: Marek Vasut <marex@denx.de> > > This patch handles the case where the PCIe link is up and running, yet drops > into the LTSSM training mode. The link spends short time in the LTSSM training > mode, but the current code can misinterpret it as the link being stalled. > Waiting for the LTSSM training to complete fixes the issue. > > Quoting Sascha, "This is broken since > commit e6daf4a5e1b813bc7f85507ec83b8c2452c121e6 > PCI: imx6: Report "link up" only after link training completes > > 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." > > Signed-off-by: Marek Vasut <marex@denx.de> > Tested-by: Troy Kisky <troy.kisky@boundarydevices.com> > Tested-by: Sascha Hauer <s.hauer@pengutronix.de> > Acked-by: Shawn Guo <shawn.guo@linaro.org> > Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com> Applied to pci/host-imx6 for v3.15, thanks! I changed the SHA1 in the changelog from e6daf4a5e1b813bc7f85507ec83b8c2452c121e6 to 7f9f40c01cce, because I think that's what's in the upstream tree. Bjorn > --- > drivers/pci/host/pci-imx6.c | 47 ++++++++++++++++++++++++++++++++------------- > 1 file changed, 34 insertions(+), 13 deletions(-) > > diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c > index e8663a8..ee08250 100644 > --- a/drivers/pci/host/pci-imx6.c > +++ b/drivers/pci/host/pci-imx6.c > @@ -424,20 +424,40 @@ 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; > + u32 rc, debug_r0, rx_valid; > + int count = 5; > > /* > - * Test if the PHY reports that the link is up and also that > - * the link training finished. It might happen that the PHY > - * reports the link is already up, but the link training bit > - * is still set, so make sure to check the training is done > - * as well here. > + * Test if the PHY reports that the link is up and also that the LTSSM > + * training finished. There are three possible states of the link when > + * this code is called: > + * 1) The link is DOWN (unlikely) > + * The link didn't come up yet for some reason. This usually means > + * we have a real problem somewhere. Reset the PHY and exit. This > + * state calls for inspection of the DEBUG registers. > + * 2) The link is UP, but still in LTSSM training > + * Wait for the training to finish, which should take a very short > + * time. If the training does not finish, we have a problem and we > + * need to inspect the DEBUG registers. If the training does finish, > + * the link is up and operating correctly. > + * 3) The link is UP and no longer in LTSSM training > + * The link is up and operating correctly. > */ > - 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)) > - return 1; > - > + while (1) { > + rc = readl(pp->dbi_base + PCIE_PHY_DEBUG_R1); > + if (!(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_UP)) > + break; > + if (!(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING)) > + return 1; > + if (!count--) > + break; > + dev_dbg(pp->dev, "Link is up, but still in training\n"); > + /* > + * Wait a little bit, then re-check if the link finished > + * the training. > + */ > + usleep_range(1000, 2000); > + } > /* > * From L0, initiate MAC entry to gen2 if EP/RC supports gen2. > * Wait 2ms (LTSSM timeout is 24ms, PHY lock is ~5us in gen2). > @@ -446,15 +466,16 @@ static int imx6_pcie_link_up(struct pcie_port *pp) > * to gen2 is stuck > */ > pcie_phy_read(pp->dbi_base, PCIE_PHY_RX_ASIC_OUT, &rx_valid); > - ltssm = readl(pp->dbi_base + PCIE_PHY_DEBUG_R0) & 0x3F; > + debug_r0 = readl(pp->dbi_base + PCIE_PHY_DEBUG_R0); > > if (rx_valid & 0x01) > return 0; > > - if (ltssm != 0x0d) > + if ((debug_r0 & 0x3f) != 0x0d) > return 0; > > dev_err(pp->dev, "transition to gen2 is stuck, reset PHY!\n"); > + dev_dbg(pp->dev, "debug_r0=%08x debug_r1=%08x\n", debug_r0, rc); > > imx6_pcie_reset_phy(pp); > > -- > 1.8.1.2 > -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c index e8663a8..ee08250 100644 --- a/drivers/pci/host/pci-imx6.c +++ b/drivers/pci/host/pci-imx6.c @@ -424,20 +424,40 @@ 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; + u32 rc, debug_r0, rx_valid; + int count = 5; /* - * Test if the PHY reports that the link is up and also that - * the link training finished. It might happen that the PHY - * reports the link is already up, but the link training bit - * is still set, so make sure to check the training is done - * as well here. + * Test if the PHY reports that the link is up and also that the LTSSM + * training finished. There are three possible states of the link when + * this code is called: + * 1) The link is DOWN (unlikely) + * The link didn't come up yet for some reason. This usually means + * we have a real problem somewhere. Reset the PHY and exit. This + * state calls for inspection of the DEBUG registers. + * 2) The link is UP, but still in LTSSM training + * Wait for the training to finish, which should take a very short + * time. If the training does not finish, we have a problem and we + * need to inspect the DEBUG registers. If the training does finish, + * the link is up and operating correctly. + * 3) The link is UP and no longer in LTSSM training + * The link is up and operating correctly. */ - 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)) - return 1; - + while (1) { + rc = readl(pp->dbi_base + PCIE_PHY_DEBUG_R1); + if (!(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_UP)) + break; + if (!(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING)) + return 1; + if (!count--) + break; + dev_dbg(pp->dev, "Link is up, but still in training\n"); + /* + * Wait a little bit, then re-check if the link finished + * the training. + */ + usleep_range(1000, 2000); + } /* * From L0, initiate MAC entry to gen2 if EP/RC supports gen2. * Wait 2ms (LTSSM timeout is 24ms, PHY lock is ~5us in gen2). @@ -446,15 +466,16 @@ static int imx6_pcie_link_up(struct pcie_port *pp) * to gen2 is stuck */ pcie_phy_read(pp->dbi_base, PCIE_PHY_RX_ASIC_OUT, &rx_valid); - ltssm = readl(pp->dbi_base + PCIE_PHY_DEBUG_R0) & 0x3F; + debug_r0 = readl(pp->dbi_base + PCIE_PHY_DEBUG_R0); if (rx_valid & 0x01) return 0; - if (ltssm != 0x0d) + if ((debug_r0 & 0x3f) != 0x0d) return 0; dev_err(pp->dev, "transition to gen2 is stuck, reset PHY!\n"); + dev_dbg(pp->dev, "debug_r0=%08x debug_r1=%08x\n", debug_r0, rc); imx6_pcie_reset_phy(pp);