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Message-Id: <20220418121200.638190092@linuxfoundation.org>
Date: Mon, 18 Apr 2022 14:11:45 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org,
Liguang Zhang <zhangliguang@...ux.alibaba.com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Lukas Wunner <lukas@...ner.de>
Subject: [PATCH 4.9 039/218] PCI: pciehp: Clear cmd_busy bit in polling mode
From: Liguang Zhang <zhangliguang@...ux.alibaba.com>
commit 92912b175178c7e895f5e5e9f1e30ac30319162b upstream.
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 <zhangliguang@...ux.alibaba.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
Reviewed-by: Lukas Wunner <lukas@...ner.de>
Cc: stable@...r.kernel.org # v4.19+
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
drivers/pci/hotplug/pciehp_hpc.c | 2 ++
1 file changed, 2 insertions(+)
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -120,6 +120,8 @@ static int pcie_poll_cmd(struct controll
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;
}
if (timeout < 0)
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