linux-kernel - [PATCH] PCI: pciehp: Add Qualcomm quirk for Command Completed erratum

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Date:   Mon, 13 Feb 2023 20:19:22 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     bhelgaas@...gle.com
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, steev@...i.org,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Subject: [PATCH] PCI: pciehp: Add Qualcomm quirk for Command Completed erratum

The Qualcomm PCI bridge device (Device ID 0x010e) found in chipsets such as
SC8280XP used in Lenovo Thinkpad X13s, does not set the Command Completed
bit unless writes to the Slot Command register change "Control" bits.

This results in timeouts like below during boot and resume from suspend:

    pcieport 0002:00:00.0: pciehp: Timeout on hotplug command 0x03c0 (issued 2020 msec ago)
    ...
    pcieport 0002:00:00.0: pciehp: Timeout on hotplug command 0x13f1 (issued 107724 msec ago)

Add the device to the Command Completed quirk to mark commands "completed"
immediately unless they change the "Control" bits.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
---

Bjorn, during the review of a similar patch adding the quirk for device id
0x0110, you asked me whether we should mark all Qcom bridge devices as
quirky like Intel bridges. I tried asking this question to Qualcomm but
found no answer yet. So I just went with adding one more entry.

 drivers/pci/hotplug/pciehp_hpc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index 10e9670eea0b..f8c70115b691 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -1088,6 +1088,8 @@ static void quirk_cmd_compl(struct pci_dev *pdev)
 }
 DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_INTEL, PCI_ANY_ID,
 			      PCI_CLASS_BRIDGE_PCI, 8, quirk_cmd_compl);
+DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_QCOM, 0x010e,
+			      PCI_CLASS_BRIDGE_PCI, 8, quirk_cmd_compl);
 DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_QCOM, 0x0110,
 			      PCI_CLASS_BRIDGE_PCI, 8, quirk_cmd_compl);
 DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_QCOM, 0x0400,
-- 
2.25.1