[patch 73/83] PCIe: ASPM: Break out of endless loop waiting for PCI config bits to switch

Greg KH
2008-12-11T19:44:29Z

[-- Attachment #1: pcie-aspm-break-out-of-endless-loop-waiting-for-pci-config-bits-to-switch.patch --]
[-- Type: text/plain, Size: 2977 bytes --]

2.6.27-stable review patch. If anyone has any objections, please let us know.

------------------

From: Thomas Renninger <trenn@suse.de>

commit 2a42d9dba7842422ffb2c02e75288a8bc2fd5065 upstream.

Makes a Compaq 6735s boot reliably again. It used to hang in the loop
on some boots. Give the link one second to train, otherwise break out
of the loop and reset the previously set clock bits.

Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Matthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/pci/pcie/aspm.c | 29 ++++++++++++++++++++++++++---
1 file changed, 26 insertions(+), 3 deletions(-)

--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -16,6 +16,7 @@
#include <linux/pm.h>
#include <linux/init.h>
#include <linux/slab.h>
+#include <linux/jiffies.h>
#include <linux/pci-aspm.h>
#include "../pci.h"

@@ -161,11 +162,12 @@ static void pcie_check_clock_pm(struct p
*/
static void pcie_aspm_configure_common_clock(struct pci_dev *pdev)
{
- int pos, child_pos;
+ int pos, child_pos, i = 0;
u16 reg16 = 0;
struct pci_dev *child_dev;
int same_clock = 1;
-
+ unsigned long start_jiffies;
+ u16 child_regs[8], parent_reg;
/*
* all functions of a slot should have the same Slot Clock
* Configuration, so just check one function
@@ -191,16 +193,19 @@ static void pcie_aspm_configure_common_c
child_pos = pci_find_capability(child_dev, PCI_CAP_ID_EXP);
pci_read_config_word(child_dev, child_pos + PCI_EXP_LNKCTL,
&reg16);
+ child_regs[i] = reg16;
if (same_clock)
reg16 |= PCI_EXP_LNKCTL_CCC;
else
reg16 &= ~PCI_EXP_LNKCTL_CCC;
pci_write_config_word(child_dev, child_pos + PCI_EXP_LNKCTL,
reg16);
+ i++;
}

/* Configure upstream component */
pci_read_config_word(pdev, pos + PCI_EXP_LNKCTL, &reg16);
+ parent_reg = reg16;
if (same_clock)
reg16 |= PCI_EXP_LNKCTL_CCC;
else
@@ -212,12 +217,30 @@ static void pcie_aspm_configure_common_c
pci_write_config_word(pdev, pos + PCI_EXP_LNKCTL, reg16);

/* Wait for link training end */
- while (1) {
+ /* break out after waiting for 1 second */
+ start_jiffies = jiffies;
+ while ((jiffies - start_jiffies) < HZ) {
pci_read_config_word(pdev, pos + PCI_EXP_LNKSTA, &reg16);
if (!(reg16 & PCI_EXP_LNKSTA_LT))
break;
cpu_relax();
}
+ /* training failed -> recover */
+ if ((jiffies - start_jiffies) >= HZ) {
+ dev_printk (KERN_ERR, &pdev->dev, "ASPM: Could not configure"
+ " common clock\n");
+ i = 0;
+ list_for_each_entry(child_dev, &pdev->subordinate->devices,
+ bus_list) {
+ child_pos = pci_find_capability(child_dev,
+ PCI_CAP_ID_EXP);
+ pci_write_config_word(child_dev,
+ child_pos + PCI_EXP_LNKCTL,
+ child_regs[i]);
+ i++;
+ }
+ pci_write_config_word(pdev, pos + PCI_EXP_LNKCTL, parent_reg);
+ }
}

/*