linux-kernel - [PATCH v4 9/9] PCI: dwc: support missing PCIe device on resume

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Message-Id: <20251029-rockchip-pcie-system-suspend-v4-9-ce2e1b0692d2@collabora.com>
Date: Wed, 29 Oct 2025 18:56:48 +0100
From: Sebastian Reichel <sebastian.reichel@...labora.com>
To: Lorenzo Pieralisi <lpieralisi@...nel.org>, 
 Krzysztof Wilczyński <kwilczynski@...nel.org>, 
 Manivannan Sadhasivam <mani@...nel.org>, Rob Herring <robh@...nel.org>, 
 Bjorn Helgaas <bhelgaas@...gle.com>, Heiko Stuebner <heiko@...ech.de>, 
 Philipp Zabel <p.zabel@...gutronix.de>, Jingoo Han <jingoohan1@...il.com>, 
 Shawn Lin <shawn.lin@...k-chips.com>
Cc: linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 kernel@...labora.com, Sebastian Reichel <sebastian.reichel@...labora.com>
Subject: [PATCH v4 9/9] PCI: dwc: support missing PCIe device on resume

When dw_pcie_resume_noirq() is called for a PCIe root complex for a PCIe
slot with no device plugged on Rockchip RK3576, dw_pcie_wait_for_link()
will return -ETIMEDOUT. During probe time this does not happen, since
the platform sets 'use_linkup_irq'.

This adds the same logic from dw_pcie_host_init() to the PM resume
function to avoid the problem.

Signed-off-by: Sebastian Reichel <sebastian.reichel@...labora.com>
---
 drivers/pci/controller/dwc/pcie-designware-host.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index e92513c5bda5..f25f1c136900 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -1215,9 +1215,16 @@ int dw_pcie_resume_noirq(struct dw_pcie *pci)
 	if (ret)
 		return ret;
 
-	ret = dw_pcie_wait_for_link(pci);
-	if (ret)
-		return ret;
+	/*
+	 * Note: Skip the link up delay only when a Link Up IRQ is present.
+	 * If there is no Link Up IRQ, we should not bypass the delay
+	 * because that would require users to manually rescan for devices.
+	 */
+	if (!pci->pp.use_linkup_irq) {
+		ret = dw_pcie_wait_for_link(pci);
+		if (ret)
+			return ret;
+	}
 
 	return ret;
 }

-- 
2.51.0