On Mon, May 18, 2015 at 01:27:37PM +0100, Chris Bainbridge wrote:
> diff --git a/drivers/acpi/sbs.c b/drivers/acpi/sbs.c
> index 01504c8..74f8596 100644
> --- a/drivers/acpi/sbs.c
> +++ b/drivers/acpi/sbs.c
> @@ -361,16 +361,21 @@ static int acpi_manager_get_info(struct acpi_sbs *sbs)
> static int acpi_battery_get_info(struct acpi_battery *battery)
> {
> int i, result = 0;
> -
> - for (i = 0; i < ARRAY_SIZE(info_readers); ++i) {
> - result = acpi_smbus_read(battery->sbs->hc,
> - info_readers[i].mode,
> - ACPI_SBS_BATTERY,
> - info_readers[i].command,
> - (u8 *) battery +
> - info_readers[i].offset);
> - if (result)
> - break;
> + int j;
> +
> + for (j = 0; j < 1000; j++) {
> + for (i = 0; i < ARRAY_SIZE(info_readers); ++i) {
> + result = acpi_smbus_read(battery->sbs->hc,
> + info_readers[i].mode,
> + ACPI_SBS_BATTERY,
> + info_readers[i].command,
> + (u8 *) battery +
> + info_readers[i].offset);
> + if (result) {
> + printk("FAIL\n");
> + break;
> + }
> + }
> }
> return result;
> }
Better to exit immediately when SBS hangs, otherwise you could be
waiting a long time for modprobe to return:
diff --git a/drivers/acpi/sbs.c b/drivers/acpi/sbs.c
index 01504c8..84f422f 100644
--- a/drivers/acpi/sbs.c
+++ b/drivers/acpi/sbs.c
@@ -361,17 +361,22 @@ static int acpi_manager_get_info(struct acpi_sbs *sbs)
static int acpi_battery_get_info(struct acpi_battery *battery)
{
int i, result = 0;
-
- for (i = 0; i < ARRAY_SIZE(info_readers); ++i) {
- result = acpi_smbus_read(battery->sbs->hc,
- info_readers[i].mode,
- ACPI_SBS_BATTERY,
- info_readers[i].command,
- (u8 *) battery +
- info_readers[i].offset);
- if (result)
- break;
+ int j;
+
+ for (j = 0; j < 100; j++) {
+ for (i = 0; i < ARRAY_SIZE(info_readers); ++i) {
+ result = acpi_smbus_read(battery->sbs->hc,
+ info_readers[i].mode,
+ ACPI_SBS_BATTERY,
+ info_readers[i].command,
+ (u8 *) battery +
+ info_readers[i].offset);
+ if (result)
+ goto end;
+ }
}
+ end:
+ printk(result ? "FAIL" : "OK");
return result;
}
I'm sure you get the idea. Forcing repeated SBS reads is a much quicker
way to uncover an intermittent fault than through normal usage. After
adding the 5us delay, I was able to run the acpi_battery_get_info loop
for 20,000 cycles without fault, but this is just one Macbook, others
may be different. It's also possible that the delay is just covering up
some other problem; some patches were posted a few days ago to fix some
underlying hang issues: http://www.spinics.net/lists/linux-acpi/msg57572.html
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