On system with 16 PCI express hotplug slots, customer complain every slot
will report "Command not completed in 1000 msec" during initialization.
Intel says that we should only wait command complete only for
Electromechanical Interlock Control
Power Controller Control
Power Indicator Control
Attention Indicator Control
System with AMD/Nvidia chipset have same problem.
Two ways to address the problem:
1. change to only wait when (EIC, PCC, PIC, AIC) bits get changed.
2. or check CMD_COMPLETE and wait before write command. Only wait
when CC is set and cmd_busy is true. For chipset from intel
will only have CC set for real hotplug control, so we could
skip the wait for others.
This patch is using second way.
With that we could save 16 seconds during booting, later with 32 sockets system
with 64 pcie hotplug slots we could save 64 seconds.
This patch address spurious "cmd completed" event problem that that
Rajat met.
-v2: use second way that is suggested by Bjorn.
-v3: rebase after
PCI: pciehp: Acknowledge spurious "cmd completed" event
Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
Tested-by: Rajat Jain <rajatxjain@xxxxxxxxx>
---
drivers/pci/hotplug/pciehp_hpc.c | 28 ++++++++++------------------
1 file changed, 10 insertions(+), 18 deletions(-)
Index: linux-2.6/drivers/pci/hotplug/pciehp_hpc.c
===================================================================
--- linux-2.6.orig/drivers/pci/hotplug/pciehp_hpc.c
+++ linux-2.6/drivers/pci/hotplug/pciehp_hpc.c
@@ -158,17 +158,8 @@ static void pcie_write_cmd(struct contro
mutex_lock(&ctrl->ctrl_lock);
pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
- if (slot_status & PCI_EXP_SLTSTA_CC) {
- pcie_capability_write_word(pdev, PCI_EXP_SLTSTA,
- PCI_EXP_SLTSTA_CC);
- if (!ctrl->no_cmd_complete) {
- /*
- * After 1 sec and CMD_COMPLETED still not set, just
- * proceed forward to issue the next command according
- * to spec. Just print out the error message.
- */
- ctrl_dbg(ctrl, "CMD_COMPLETED not clear after 1 sec\n");
- } else if (!NO_CMD_CMPL(ctrl)) {
+ if (ctrl->no_cmd_complete && slot_status & PCI_EXP_SLTSTA_CC) {
+ if (!NO_CMD_CMPL(ctrl)) {
/*
* This controller seems to notify of command completed
* event even though it supports none of power
@@ -184,16 +175,11 @@ static void pcie_write_cmd(struct contro
}
pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &slot_ctrl);
- slot_ctrl &= ~mask;
- slot_ctrl |= (cmd & mask);
- ctrl->cmd_busy = 1;
- smp_mb();
- pcie_capability_write_word(pdev, PCI_EXP_SLTCTL, slot_ctrl);
-
/*
* Wait for command completion.
*/
- if (!ctrl->no_cmd_complete) {
+ if (!ctrl->no_cmd_complete && (slot_status & PCI_EXP_SLTSTA_CC) &&
+ ctrl->cmd_busy) {
int poll = 0;
/*
* if hotplug interrupt is not enabled or command
@@ -205,6 +191,12 @@ static void pcie_write_cmd(struct contro
poll = 1;
pcie_wait_cmd(ctrl, poll);
}
+
+ slot_ctrl &= ~mask;
+ slot_ctrl |= (cmd & mask);
+ ctrl->cmd_busy = 1;
+ smp_mb();
+ pcie_capability_write_word(pdev, PCI_EXP_SLTCTL, slot_ctrl);
mutex_unlock(&ctrl->ctrl_lock);
}
--
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