[PATCH v5 3/3] PCI: qcom: Add retry logic for link to be stable in L1ss

Krishna chaitanya chundru
2022-08-03T11:29:18Z

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 | 25 ++++++++++++++++++++-----
1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index f7dd5dc..f3201bd 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -1829,15 +1829,30 @@ static int __maybe_unused qcom_pcie_pm_suspend(struct device *dev)
{
struct qcom_pcie *pcie = dev_get_drvdata(dev);
u32 val;
+ ktime_t timeout, start;

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

- /* 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;
+ start = ktime_get();
+ /* Wait max 100 ms */
+ timeout = ktime_add_ms(start, 100);
+ while (1) {
+ bool timedout = ktime_after(ktime_get(), timeout);
+
+ /* 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_info(dev, "Link enters L1ss after %d ms\n",
+ ktime_to_ms(ktime_get() - start));
+ break;
+ }
+
+ if (timedout) {
+ dev_warn(dev, "Link is not in L1ss\n");
+ return 0;
+ }
+ usleep_range(1000, 1200);
}

if (pcie->cfg->ops->suspend)
--
2.7.4