shark/bbswitch-g14
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Power on the PCIe port before accessing PCI config space (#35)

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Fixes regression in Linux 3.6 when run-time power management is enabled. See
https://bugzilla.kernel.org/show_bug.cgi?id=48981 for a discussion.
This commit is contained in:
Peter Wu
2012-10-19 17:28:59 +02:00
parent b8a6029692
commit 7f9fb7adf9
1 changed files with 32 additions and 1 deletions
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33
bbswitch.c
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@@ -17,6 +17,7 @@
#include <asm/uaccess.h>
#include <linux/suspend.h>
#include <linux/seq_file.h>
#include <linux/pm_runtime.h>
#define BBSWITCH_VERSION "0.4.2"
@@ -256,6 +257,17 @@ static void bbswitch_on(void) {
pci_set_master(dis_dev);
}
/* power bus so we can read PCI configuration space */
static void dis_dev_get(void) {
if (dis_dev->bus && dis_dev->bus->self)
pm_runtime_get_sync(&dis_dev->bus->self->dev);
}
static void dis_dev_put(void) {
if (dis_dev->bus && dis_dev->bus->self)
pm_runtime_put_sync(&dis_dev->bus->self->dev);
}
static ssize_t bbswitch_proc_write(struct file *fp, const char __user *buff,
size_t len, loff_t *off) {
char cmd[8];
@@ -266,19 +278,25 @@ static ssize_t bbswitch_proc_write(struct file *fp, const char __user *buff,
if (copy_from_user(cmd, buff, len))
return -EFAULT;
dis_dev_get();
if (strncmp(cmd, "OFF", 3) == 0)
bbswitch_off();
if (strncmp(cmd, "ON", 2) == 0)
bbswitch_on();
dis_dev_put();
return len;
}
static int bbswitch_proc_show(struct seq_file *seqfp, void *p) {
// show the card state. Example output: 0000:01:00:00 ON
dis_dev_get();
seq_printf(seqfp, "%s %s\n", dev_name(&dis_dev->dev),
is_card_disabled() ? "OFF" : "ON");
dis_dev_put();
return 0;
}
static int bbswitch_proc_open(struct inode *inode, struct file *file) {
@@ -290,19 +308,24 @@ static int bbswitch_pm_handler(struct notifier_block *nbp,
switch (event_type) {
case PM_HIBERNATION_PREPARE:
case PM_SUSPEND_PREPARE:
dis_dev_get();
dis_before_suspend_disabled = is_card_disabled();
// enable the device before suspend to avoid the PCI config space from
// being saved incorrectly
if (dis_before_suspend_disabled)
bbswitch_on();
dis_dev_put();
break;
case PM_POST_HIBERNATION:
case PM_POST_SUSPEND:
case PM_POST_RESTORE:
// after suspend, the card is on, but if it was off before suspend,
// disable it again
if (dis_before_suspend_disabled)
if (dis_before_suspend_disabled) {
dis_dev_get();
bbswitch_off();
dis_dev_put();
}
break;
case PM_RESTORE_PREPARE:
// deliberately don't do anything as it does not occur before suspend
@@ -390,6 +413,8 @@ static int __init bbswitch_init(void) {
return -ENOMEM;
}
dis_dev_get();
if (load_state == CARD_ON)
bbswitch_on();
else if (load_state == CARD_OFF)
@@ -398,6 +423,8 @@ static int __init bbswitch_init(void) {
pr_info("Succesfully loaded. Discrete card %s is %s\n",
dev_name(&dis_dev->dev), is_card_disabled() ? "off" : "on");
dis_dev_put();
nb.notifier_call = &bbswitch_pm_handler;
register_pm_notifier(&nb);
@@ -407,6 +434,8 @@ static int __init bbswitch_init(void) {
static void __exit bbswitch_exit(void) {
remove_proc_entry("bbswitch", acpi_root_dir);
dis_dev_get();
if (unload_state == CARD_ON)
bbswitch_on();
else if (unload_state == CARD_OFF)
@@ -415,6 +444,8 @@ static void __exit bbswitch_exit(void) {
pr_info("Unloaded. Discrete card %s is %s\n",
dev_name(&dis_dev->dev), is_card_disabled() ? "off" : "on");
dis_dev_put();
if (nb.notifier_call)
unregister_pm_notifier(&nb);
}