On Wed, Jun 07, 2023 at 02:44:27PM +0530, Siddharth Vadapalli wrote: > The Link Retraining process is initiated to account for the Gen2 defect in > the Cadence PCIe controller in J721E SoC. The errata corresponding to this > is i2085, documented at: > https://www.ti.com/lit/er/sprz455c/sprz455c.pdf > > The existing workaround implemented for the errata waits for the Data Link > initialization to complete and assumes that the link retraining process > at the Physical Layer has completed. However, it is possible that the > Physical Layer training might be ongoing as indicated by the > PCI_EXP_LNKSTA_LT bit in the PCI_EXP_LNKSTA register. > > Fix the existing workaround, to ensure that the Physical Layer training > has also completed, in addition to the Data Link initialization. > cdns_pcie_host_wait_for_link() function is called even for the non-quirky cases as well, so does this patch. But if your patch is only targeting the link retraining case, you should move the logic to cdns_pcie_retrain(). > Fixes: 4740b969aaf5 ("PCI: cadence: Retrain Link to work around Gen2 training defect") > Signed-off-by: Siddharth Vadapalli <s-vadapalli@xxxxxx> > Reviewed-by: Vignesh Raghavendra <vigneshr@xxxxxx> > --- > > Hello, > > This patch is based on linux-next tagged next-20230606. > > v2: > https://lore.kernel.org/r/20230315070800.1615527-1-s-vadapalli@xxxxxx/ > Changes since v2: > - Merge the cdns_pcie_host_training_complete() function with the > cdns_pcie_host_wait_for_link() function, as suggested by Bjorn > for the v2 patch. > - Add dev_err() to notify when Link Training fails, since this is a > fatal error and proceeding from this point will almost always crash > the kernel. > > v1: > https://lore.kernel.org/r/20230102075656.260333-1-s-vadapalli@xxxxxx/ > Changes since v1: > - Collect Reviewed-by tag from Vignesh Raghavendra. > - Rebase on next-20230315. > > Regards, > Siddharth. > > .../controller/cadence/pcie-cadence-host.c | 20 +++++++++++++++++++ > 1 file changed, 20 insertions(+) > > diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c > index 940c7dd701d6..70a5f581ff4f 100644 > --- a/drivers/pci/controller/cadence/pcie-cadence-host.c > +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c > @@ -12,6 +12,8 @@ > > #include "pcie-cadence.h" > > +#define LINK_RETRAIN_TIMEOUT HZ > + > static u64 bar_max_size[] = { > [RP_BAR0] = _ULL(128 * SZ_2G), > [RP_BAR1] = SZ_2G, > @@ -80,8 +82,26 @@ static struct pci_ops cdns_pcie_host_ops = { > static int cdns_pcie_host_wait_for_link(struct cdns_pcie *pcie) > { > struct device *dev = pcie->dev; > + unsigned long end_jiffies; > + u16 link_status; > int retries; > > + /* Wait for link training to complete */ > + end_jiffies = jiffies + LINK_RETRAIN_TIMEOUT; > + do { > + link_status = cdns_pcie_rp_readw(pcie, CDNS_PCIE_RP_CAP_OFFSET + PCI_EXP_LNKSTA); > + if (!(link_status & PCI_EXP_LNKSTA_LT)) > + break; > + usleep_range(0, 1000); > + } while (time_before(jiffies, end_jiffies)); > + > + if (!(link_status & PCI_EXP_LNKSTA_LT)) { > + dev_info(dev, "Link training complete\n"); This info is not needed. > + } else { > + dev_err(dev, "Fatal! Link training incomplete\n"); This could be, "Link retraining incomplete". - Mani > + return -ETIMEDOUT; > + } > + > /* Check if the link is up or not */ > for (retries = 0; retries < LINK_WAIT_MAX_RETRIES; retries++) { > if (cdns_pcie_link_up(pcie)) { > -- > 2.25.1 > -- மணிவண்ணன் சதாசிவம்
