[PATCH v4 2/2] PCI: dwc: Clean up some unnecessary codes in dw_pcie_suspend_noirq()

Richard Zhu
2024-12-10T08:16:50Z

Before sending PME_TURN_OFF, don't test the LTSSM state. Since it's safe
to send PME_TURN_OFF message regardless of whether the link is up or
down. So, there would be no need to test the LTSSM state before sending
PME_TURN_OFF message.

Only print the message when ltssm_stat is not in DETECT and POLL.
In the other words, there isn't an error message when no endpoint is
connected at all.

Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
.../pci/controller/dwc/pcie-designware-host.c | 27 ++++++++++++-------
drivers/pci/controller/dwc/pcie-designware.h | 1 +
2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index f56cb7b9e6f99..bdb9c1ad6cdd5 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -973,7 +973,7 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci)
{
u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
u32 val;
- int ret = 0;
+ int ret;

/*
* If L1SS is supported, then do not put the link into L2 as some
@@ -982,25 +982,32 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci)
if (dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKCTL) & PCI_EXP_LNKCTL_ASPM_L1)
return 0;

- if (dw_pcie_get_ltssm(pci) <= DW_PCIE_LTSSM_DETECT_ACT)
- return 0;
-
- if (pci->pp.ops->pme_turn_off)
+ if (pci->pp.ops->pme_turn_off) {
pci->pp.ops->pme_turn_off(&pci->pp);
- else
+ } else {
ret = dw_pcie_pme_turn_off(pci);
+ if (ret)
+ return ret;
+ }

- if (ret)
- return ret;
-
- ret = read_poll_timeout(dw_pcie_get_ltssm, val, val == DW_PCIE_LTSSM_L2_IDLE,
+ ret = read_poll_timeout(dw_pcie_get_ltssm, val,
+ val == DW_PCIE_LTSSM_L2_IDLE ||
+ val <= DW_PCIE_LTSSM_DETECT_WAIT,
PCIE_PME_TO_L2_TIMEOUT_US/10,
PCIE_PME_TO_L2_TIMEOUT_US, false, pci);
if (ret) {
+ /* Only dump message when ltssm_stat isn't in DETECT and POLL */
dev_err(pci->dev, "Timeout waiting for L2 entry! LTSSM: 0x%x\n", val);
return ret;
}

+ /*
+ * Refer to r6.0, sec 5.3.3.2.1, software should wait at least
+ * 100ns after L2/L3 Ready before turning off refclock and
+ * main power. It's harmless too when no endpoint connected.
+ */
+ udelay(1);
+
dw_pcie_stop_link(pci);
if (pci->pp.ops->deinit)
pci->pp.ops->deinit(&pci->pp);
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 5c14ed2cb91ed..7efcb4af66da3 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -330,6 +330,7 @@ enum dw_pcie_ltssm {
/* Need to align with PCIE_PORT_DEBUG0 bits 0:5 */
DW_PCIE_LTSSM_DETECT_QUIET = 0x0,
DW_PCIE_LTSSM_DETECT_ACT = 0x1,
+ DW_PCIE_LTSSM_DETECT_WAIT = 0x6,
DW_PCIE_LTSSM_L0 = 0x11,
DW_PCIE_LTSSM_L2_IDLE = 0x15,

--
2.37.1