Current L2 state polling with 1us interval is too aggressive. Based on
the experiments with different endpoints, LTSSM state transisition to L2
is happening between 6us ~ 40us. Hence, update the polling delay for L2
state from 1us to 100us for a better utilization of CPU cycles.
Fixes: 56e15a238d92 ("PCI: tegra: Add Tegra194 PCIe support")
Signed-off-by: Vidya Sagar <vidyas@xxxxxxxxxx>
---
drivers/pci/controller/dwc/pcie-tegra194.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index d053e52b1778..de477192c4b8 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -206,7 +206,8 @@
#define CAP_SPCIE_CAP_OFF_USP_TX_PRESET0_MASK GENMASK(11, 8)
#define CAP_SPCIE_CAP_OFF_USP_TX_PRESET0_SHIFT 8
-#define PME_ACK_TIMEOUT 10000
+#define PME_ACK_DELAY 100 /* 100 us */
+#define PME_ACK_TIMEOUT 10000 /* 10 ms */
#define LTSSM_TIMEOUT 50000 /* 50ms */
@@ -1556,7 +1557,7 @@ static int tegra_pcie_try_link_l2(struct tegra_pcie_dw *pcie)
return readl_poll_timeout_atomic(pcie->appl_base + APPL_DEBUG, val,
val & APPL_DEBUG_PM_LINKST_IN_L2_LAT,
- 1, PME_ACK_TIMEOUT);
+ PME_ACK_DELAY, PME_ACK_TIMEOUT);
}
static void tegra_pcie_dw_pme_turnoff(struct tegra_pcie_dw *pcie)
--
2.17.1
