[PATCH v6 2/5] PCI: qcom: Add retry logic for link to be stable in L1ss

Krishna chaitanya chundru
2022-09-09T08:45:49Z

Some specific devices are taking time to settle the link in L1ss.
So added a retry logic before returning from the suspend op.

Signed-off-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>
---
drivers/pci/controller/dwc/pcie-qcom.c | 36 +++++++++++++++++++++++-----------
1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 6e04d0d..15c2067 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -1809,26 +1809,40 @@ static int qcom_pcie_probe(struct platform_device *pdev)
static int __maybe_unused qcom_pcie_pm_suspend(struct qcom_pcie *pcie)
{
u32 val;
+ ktime_t timeout, start;
struct dw_pcie *pci = pcie->pci;
struct device *dev = pci->dev;

if (!pcie->cfg->supports_system_suspend)
return 0;

- /* if the link is not active turn off clocks */
- if (!dw_pcie_link_up(pci)) {
- dev_info(dev, "Link is not active\n");
- goto suspend;
- }
+ start = ktime_get();
+ /* Wait max 200 ms */
+ timeout = ktime_add_ms(start, 200);

- /* if the link is not in l1ss don't turn off clocks */
- val = readl(pcie->parf + PCIE20_PARF_PM_STTS);
- if (!(val & PCIE20_PARF_PM_STTS_LINKST_IN_L1SUB)) {
- dev_warn(dev, "Link is not in L1ss\n");
- return 0;
+ while (1) {
+
+ if (!dw_pcie_link_up(pci)) {
+ dev_warn(dev, "Link is not active\n");
+ break;
+ }
+
+ /* if the link is not in l1ss don't turn off clocks */
+ val = readl(pcie->parf + PCIE20_PARF_PM_STTS);
+ if ((val & PCIE20_PARF_PM_STTS_LINKST_IN_L1SUB)) {
+ dev_dbg(dev, "Link enters L1ss after %d ms\n",
+ ktime_to_ms(ktime_get() - start));
+ break;
+ }
+
+ if (ktime_after(ktime_get(), timeout)) {
+ dev_warn(dev, "Link is not in L1ss\n");
+ return 0;
+ }
+
+ udelay(1000);
}

-suspend:
if (pcie->cfg->ops->suspend)
pcie->cfg->ops->suspend(pcie);

--
2.7.4