[PATCH V3 03/21] PCI: tegra194: Fix polling delay for L2 state

Vidya Sagar
2022-10-13T18:42:38Z

As per PCIe spec r6.0, sec 5.3.3.2.1, after sending PME_Turn_Off message,
Root port should wait for 1~10 msec for PME_TO_Ack message. Currently,
driver is polling for 10 msec with 1 usec delay which is aggressive.
Change it to 10 msec polling with 100 usec delay. Since this function
is used in non-atomic context only, use non-atomic poll function.

Fixes: 56e15a238d92 ("PCI: tegra: Add Tegra194 PCIe support")
Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
---
V3:
* Changed atomic call to non-atomic call
* Reworded the commit message

V2:
* None

drivers/pci/controller/dwc/pcie-tegra194.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index a33c86e3de9d..685aee378c93 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -207,7 +207,8 @@
#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 */

@@ -1611,9 +1612,9 @@ static int tegra_pcie_try_link_l2(struct tegra_pcie_dw *pcie)
val |= APPL_PM_XMT_TURNOFF_STATE;
appl_writel(pcie, val, APPL_RADM_STATUS);

- return readl_poll_timeout_atomic(pcie->appl_base + APPL_DEBUG, val,
- val & APPL_DEBUG_PM_LINKST_IN_L2_LAT,
- 1, PME_ACK_TIMEOUT);
+ return readl_poll_timeout(pcie->appl_base + APPL_DEBUG, val,
+ val & APPL_DEBUG_PM_LINKST_IN_L2_LAT,
+ PME_ACK_DELAY, PME_ACK_TIMEOUT);
}

static void tegra_pcie_dw_pme_turnoff(struct tegra_pcie_dw *pcie)
--
2.17.1