This is a note to let you know that I've just added the patch titled
PCI: cadence: Fix Gen2 Link Retraining process
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pci-cadence-fix-gen2-link-retraining-process.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 540e78a127cd9518a8ae69e551982c7bc511a0c8
Author: Siddharth Vadapalli <s-vadapalli@xxxxxx>
Date: Wed Mar 15 12:38:00 2023 +0530
PCI: cadence: Fix Gen2 Link Retraining process
[ Upstream commit 0e12f830236928b6fadf40d917a7527f0a048d2f ]
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.
Link: https://lore.kernel.org/r/20230315070800.1615527-1-s-vadapalli@xxxxxx
Fixes: 4740b969aaf5 ("PCI: cadence: Retrain Link to work around Gen2 training defect")
Signed-off-by: Siddharth Vadapalli <s-vadapalli@xxxxxx>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@xxxxxxxxxx>
Reviewed-by: Vignesh Raghavendra <vigneshr@xxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
index fb96d37a135c1..4d8d15ac51ef4 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,
@@ -77,6 +79,27 @@ static struct pci_ops cdns_pcie_host_ops = {
.write = pci_generic_config_write,
};
+static int cdns_pcie_host_training_complete(struct cdns_pcie *pcie)
+{
+ u32 pcie_cap_off = CDNS_PCIE_RP_CAP_OFFSET;
+ unsigned long end_jiffies;
+ u16 lnk_stat;
+
+ /* Wait for link training to complete. Exit after timeout. */
+ end_jiffies = jiffies + LINK_RETRAIN_TIMEOUT;
+ do {
+ lnk_stat = cdns_pcie_rp_readw(pcie, pcie_cap_off + PCI_EXP_LNKSTA);
+ if (!(lnk_stat & PCI_EXP_LNKSTA_LT))
+ break;
+ usleep_range(0, 1000);
+ } while (time_before(jiffies, end_jiffies));
+
+ if (!(lnk_stat & PCI_EXP_LNKSTA_LT))
+ return 0;
+
+ return -ETIMEDOUT;
+}
+
static int cdns_pcie_host_wait_for_link(struct cdns_pcie *pcie)
{
struct device *dev = pcie->dev;
@@ -118,6 +141,10 @@ static int cdns_pcie_retrain(struct cdns_pcie *pcie)
cdns_pcie_rp_writew(pcie, pcie_cap_off + PCI_EXP_LNKCTL,
lnk_ctl);
+ ret = cdns_pcie_host_training_complete(pcie);
+ if (ret)
+ return ret;
+
ret = cdns_pcie_host_wait_for_link(pcie);
}
return ret;
