From 92912b175178c7e895f5e5e9f1e30ac30319162b Mon Sep 17 00:00:00 2001 From: Liguang Zhang Date: Thu, 11 Nov 2021 13:42:58 +0800 Subject: [PATCH 1/2] PCI: pciehp: Clear cmd_busy bit in polling mode Writes to a Downstream Port's Slot Control register are PCIe hotplug "commands." If the Port supports Command Completed events, software must wait for a command to complete before writing to Slot Control again. pcie_do_write_cmd() sets ctrl->cmd_busy when it writes to Slot Control. If software notification is enabled, i.e., PCI_EXP_SLTCTL_HPIE and PCI_EXP_SLTCTL_CCIE are set, ctrl->cmd_busy is cleared by pciehp_isr(). But when software notification is disabled, as it is when pcie_init() powers off an empty slot, pcie_wait_cmd() uses pcie_poll_cmd() to poll for command completion, and it neglects to clear ctrl->cmd_busy, which leads to spurious timeouts: pcieport 0000:00:03.0: pciehp: Timeout on hotplug command 0x01c0 (issued 2264 msec ago) pcieport 0000:00:03.0: pciehp: Timeout on hotplug command 0x05c0 (issued 2288 msec ago) Clear ctrl->cmd_busy in pcie_poll_cmd() when it detects a Command Completed event (PCI_EXP_SLTSTA_CC). [bhelgaas: commit log] Fixes: a5dd4b4b0570 ("PCI: pciehp: Wait for hotplug command completion where necessary") Link: https://lore.kernel.org/r/20211111054258.7309-1-zhangliguang@linux.alibaba.com Link: https://bugzilla.kernel.org/show_bug.cgi?id=215143 Link: https://lore.kernel.org/r/20211126173309.GA12255@wunner.de Signed-off-by: Liguang Zhang Signed-off-by: Bjorn Helgaas Reviewed-by: Lukas Wunner Cc: stable@vger.kernel.org # v4.19+ --- 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 1c1ebf3dad43..85dce560831a 100644 --- a/drivers/pci/hotplug/pciehp_hpc.c +++ b/drivers/pci/hotplug/pciehp_hpc.c @@ -98,6 +98,8 @@ static int pcie_poll_cmd(struct controller *ctrl, int timeout) if (slot_status & PCI_EXP_SLTSTA_CC) { pcie_capability_write_word(pdev, PCI_EXP_SLTSTA, PCI_EXP_SLTSTA_CC); + ctrl->cmd_busy = 0; + smp_mb(); return 1; } msleep(10); From 9f72d4757cbe4d1ed669192f6d23817c9e437c4b Mon Sep 17 00:00:00 2001 From: Manivannan Sadhasivam Date: Thu, 10 Feb 2022 20:20:03 +0530 Subject: [PATCH 2/2] PCI: pciehp: Add Qualcomm quirk for Command Completed erratum The Qualcomm PCI bridge device (Device ID 0x0110) found in chipsets such as SM8450 does not set the Command Completed bit unless writes to the Slot Command register change "Control" bits. This results in timeouts like below: pcieport 0001:00:00.0: pciehp: Timeout on hotplug command 0x03c0 (issued 2020 msec ago) Add the device to the Command Completed quirk to mark commands "completed" immediately unless they change the "Control" bits. Link: https://lore.kernel.org/r/20220210145003.135907-1-manivannan.sadhasivam@linaro.org Signed-off-by: Manivannan Sadhasivam Signed-off-by: Bjorn Helgaas --- 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 85dce560831a..040ae076ec0e 100644 --- a/drivers/pci/hotplug/pciehp_hpc.c +++ b/drivers/pci/hotplug/pciehp_hpc.c @@ -1086,6 +1086,8 @@ 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, 0x0110, + PCI_CLASS_BRIDGE_PCI, 8, quirk_cmd_compl); DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_QCOM, 0x0400, PCI_CLASS_BRIDGE_PCI, 8, quirk_cmd_compl); DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_QCOM, 0x0401,