From: Rajat Jain <rajatjain.linux@gmail.com>
To: linux-pci@vger.kernel.org, linux-hotplug@vger.kernel.org,
Bjorn Helgaas <bhelgaas@google.com>,
Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>,
Yijing Wang <wangyijing@huawei.com>
Cc: Guenter Roeck <groeck@juniper.net>,
Rajat Jain <rajatjain@juniper.net>,
Greg KH <gregkh@linuxfoundation.org>,
Tom Nguyen <tom.l.nguyen@intel.com>,
Kristen Accardi <kristen.c.accardi@intel.com>,
Rajat Jain <rajatxjain@gmail.com>
Subject: [PATCH] pciehp: Acknowledge the spurious "cmd completed" event.
Date: Tue, 05 Nov 2013 22:33:28 +0000 [thread overview]
Message-ID: <52797238.8070304@gmail.com> (raw)
In case of a spurious "cmd completed", pcie_write_cmd() does not
clear it, but yet expects more "cmd completed" events to be generated.
This does not happen because the previous (spurious) event has not
been acknowledged. Fix that.
Signed-off-by: Rajat Jain <rajatjain@juniper.net>
Signed-off-by: Guenter Roeck <groeck@juniper.net>
---
This is how I saw it in action: my controller does not implement any
hot-plug elements (LED, power ctrl, EMI etc) but still supports Command
completed bit.
- During initialization,
pcie_disable_notification()
-> pcie_write_cmd()
-> writes to Slot control register
-> which causes PCI_EXP_SLTSTA_CC to get set, which is not
cleared, because IRQ is not generated (we just disabled
notifications).
- After some time,
pcie_enable_notification()
-> pcie_write_cmd()
-> finds PCI_EXP_SLTSTA_CC is set, assumes it is spurious.
-> Does not clear it, yet expects more command completed
events to be generated (never happens).
drivers/pci/hotplug/pciehp_hpc.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index 5b8d749..ba8e06f 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -185,6 +185,7 @@ static int pcie_write_cmd(struct controller *ctrl, u16 cmd, u16 mask)
}
if (slot_status & PCI_EXP_SLTSTA_CC) {
+ pciehp_writew(ctrl, PCI_EXP_SLTSTA, PCI_EXP_SLTSTA_CC);
if (!ctrl->no_cmd_complete) {
/*
* After 1 sec and CMD_COMPLETED still not set, just
--
1.7.9.5
next reply other threads:[~2013-11-05 22:33 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-05 22:33 Rajat Jain [this message]
2013-11-06 0:25 ` [PATCH] pciehp: Acknowledge the spurious "cmd completed" event Bjorn Helgaas
2013-11-06 2:38 ` Rajat Jain
2013-11-07 21:53 ` Rajat Jain
2013-11-08 1:23 ` Bjorn Helgaas
2013-11-08 17:30 ` Rajat Jain
2013-11-08 23:15 ` Bjorn Helgaas
2013-11-11 21:26 ` Rajat Jain
2013-11-23 0:51 ` Bjorn Helgaas
2013-11-23 1:59 ` Guenter Roeck
2013-11-23 14:56 ` Rajat Jain
2013-11-23 19:32 ` Bjorn Helgaas
2013-11-25 19:03 ` Rajat Jain
2014-02-12 0:34 ` Bjorn Helgaas
2014-02-12 1:08 ` Rajat Jain
2014-02-20 7:42 ` Rajat Jain
2014-02-20 22:20 ` Bjorn Helgaas
2014-02-21 1:43 ` Rajat Jain
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