[PATCH 1/2] PCI: cadence: Ensure that cdns_pcie_host_wait_for_link() waits 100 ms after link up

Hans Zhang
2026-05-01T15:36:33Z

As per PCIe r6.0, sec 6.6.1, a Downstream Port that supports Link speeds
greater than 5.0 GT/s, software must wait a minimum of 100 ms after Link
training completes before sending a Configuration Request.

Add a new 'max_link_speed' field in struct cdns_pcie to record the
maximum supported (or currently configured) link speed of the controller.

In cdns_pcie_host_wait_for_link(), after the link is reported as up,
insert a 100 ms delay if max_link_speed > 2 (i.e., > 5 GT/s). This
implements the required delay at the common Cadence host layer.

Currently max_link_speed is zero-initialized, so the delay is not yet
active. Glue drivers must set max_link_speed appropriately to enable
the delay. This matches the approach taken for the Synopsys DWC
controller in commit 80dc18a0cba8d ("PCI: dwc: Ensure that
dw_pcie_wait_for_link() waits 100 ms after link up").

Signed-off-by: Hans Zhang <18255117159@163.com>
---
.../pci/controller/cadence/pcie-cadence-host-common.c | 9 +++++++++
drivers/pci/controller/cadence/pcie-cadence.h | 2 ++
2 files changed, 11 insertions(+)

diff --git a/drivers/pci/controller/cadence/pcie-cadence-host-common.c b/drivers/pci/controller/cadence/pcie-cadence-host-common.c
index 2b0211870f02..d4ae762f423f 100644
--- a/drivers/pci/controller/cadence/pcie-cadence-host-common.c
+++ b/drivers/pci/controller/cadence/pcie-cadence-host-common.c
@@ -14,6 +14,7 @@

#include "pcie-cadence.h"
#include "pcie-cadence-host-common.h"
+#include "../../pci.h"

#define LINK_RETRAIN_TIMEOUT HZ

@@ -55,6 +56,14 @@ int cdns_pcie_host_wait_for_link(struct cdns_pcie *pcie,
/* Check if the link is up or not */
for (retries = 0; retries < LINK_WAIT_MAX_RETRIES; retries++) {
if (pcie_link_up(pcie)) {
+ /*
+ * As per PCIe r6.0, sec 6.6.1, a Downstream Port that
+ * supports Link speeds greater than 5.0 GT/s, software
+ * must wait a minimum of 100 ms after Link training
+ * completes before sending a Configuration Request.
+ */
+ if (pcie->max_link_speed > 2)
+ msleep(PCIE_RESET_CONFIG_WAIT_MS);
dev_info(dev, "Link up\n");
return 0;
}
diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
index 574e9cf4d003..e222b095d2b6 100644
--- a/drivers/pci/controller/cadence/pcie-cadence.h
+++ b/drivers/pci/controller/cadence/pcie-cadence.h
@@ -86,6 +86,7 @@ struct cdns_plat_pcie_of_data {
* @ops: Platform-specific ops to control various inputs from Cadence PCIe
* wrapper
* @cdns_pcie_reg_offsets: Register bank offsets for different SoC
+ * @max_link_speed: maximum supported link speed
*/
struct cdns_pcie {
void __iomem *reg_base;
@@ -98,6 +99,7 @@ struct cdns_pcie {
struct device_link **link;
const struct cdns_pcie_ops *ops;
const struct cdns_plat_pcie_of_data *cdns_pcie_reg_offsets;
+ int max_link_speed;
};

/**
--
2.34.1