linux-kernel - [PATCH v3 1/3] PCI: dwc: Fix resume failure if no EP is connected on some platforms

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Message-Id: <20241209073924.2155933-2-hongxing.zhu@nxp.com>
Date: Mon,  9 Dec 2024 15:39:22 +0800
From: Richard Zhu <hongxing.zhu@....com>
To: jingoohan1@...il.com,
	bhelgaas@...gle.com,
	lpieralisi@...nel.org,
	kw@...ux.com,
	manivannan.sadhasivam@...aro.org,
	robh@...nel.org,
	frank.li@....com,
	quic_krichai@...cinc.com
Cc: imx@...ts.linux.dev,
	kernel@...gutronix.de,
	linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Richard Zhu <hongxing.zhu@....com>,
	Frank Li <Frank.Li@....com>
Subject: [PATCH v3 1/3] PCI: dwc: Fix resume failure if no EP is connected on 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.

Call 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>
Reviewed-by: Frank Li <Frank.Li@....com>
---
 .../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 f882b11fd7b94..11563402c571b 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -982,23 +982,23 @@ 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);
+	/* Only send out PME_TURN_OFF when PCIE link is up */
+	if (dw_pcie_get_ltssm(pci) > DW_PCIE_LTSSM_DETECT_ACT) {
+		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