linux-kernel - [PATCH v1] PCI: dwc: Fix resume failure if no EP is connected at some platforms.

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Date: Tue, 14 May 2024 13:09:18 +0800
From: Richard Zhu <hongxing.zhu@....com>
To: bhelgaas@...gle.com,
	lorenzo.pieralisi@....com,
	frank.li@....com,
	mani@...nel.org
Cc: linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	kernel@...gutronix.de,
	imx@...ts.linux.dev,
	Richard Zhu <hongxing.zhu@....com>
Subject: [PATCH v1] PCI: dwc: Fix resume failure if no EP is connected at some platforms.

The dw_pcie_suspend_noirq() function currently returns success directly
if no endpoint (EP) device is connected. However, on some platforms, power
loss occurs during suspend, causing dw_resume() to do nothing in this case.
This results in a system halt because the DWC controller is not initialized
after power-on during resume.

Change call to deinit() in suspend and init() at resume regardless of
whether there are EP device connections or not. It is not harmful to
perform deinit() and init() again for the no power-off case, and it keeps
the code simple and consistent in logic.

Fixes: 4774faf854f5 ("PCI: dwc: Implement generic suspend/resume functionality")
Signed-off-by: Richard Zhu <hongxing.zhu@....com>
---
https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/log/?h=controller/dwc
This patch depends on the branch listed above, because it's not in pci-next.
But suppose it will be in there soon.

 .../pci/controller/dwc/pcie-designware-host.c | 30 +++++++++----------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index a0822d5371bc5..cb8c3c2bcc790 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -933,23 +933,23 @@ 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)
-		pci->pp.ops->pme_turn_off(&pci->pp);
-	else
-		ret = dw_pcie_pme_turn_off(pci);
+	if (dw_pcie_get_ltssm(pci) > DW_PCIE_LTSSM_DETECT_ACT) {
+		/* Only send out PME_TURN_OFF when PCIE link is up */
+		if (pci->pp.ops->pme_turn_off)
+			pci->pp.ops->pme_turn_off(&pci->pp);
+		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,
-				PCIE_PME_TO_L2_TIMEOUT_US/10,
-				PCIE_PME_TO_L2_TIMEOUT_US, false, pci);
-	if (ret) {
-		dev_err(pci->dev, "Timeout waiting for L2 entry! LTSSM: 0x%x\n", val);
-		return ret;
+		ret = read_poll_timeout(dw_pcie_get_ltssm, val, val == DW_PCIE_LTSSM_L2_IDLE,
+					PCIE_PME_TO_L2_TIMEOUT_US/10,
+					PCIE_PME_TO_L2_TIMEOUT_US, false, pci);
+		if (ret) {
+			dev_err(pci->dev, "Timeout waiting for L2 entry! LTSSM: 0x%x\n", val);
+			return ret;
+		}
 	}
 
 	if (pci->pp.ops->deinit)
-- 
2.37.1