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SubjectRe: [PATCH] ACPI/Battery: Retry to get Battery information if failed during probing
On Thu, 12 Jun 2014, Lan Tianyu wrote:

> Some machines'(E,G Lenovo Z480) ECs are not stable during boot up
> and causes battery driver fails to be probed due to failure of getting
> battery information from EC sometimes. After several retries, the
> operation will work. This patch is to retry to get battery information 5
> times if the first try fails.
>
> Reported-and-tested-by: naszar <naszar@ya.ru>
> Reference: https://bugzilla.kernel.org/show_bug.cgi?id=75581
> Cc: stable@vger.kernel.org
> Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
> ---
> drivers/acpi/battery.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
> index e48fc98..485009d 100644
> --- a/drivers/acpi/battery.c
> +++ b/drivers/acpi/battery.c
> @@ -34,6 +34,7 @@
> #include <linux/dmi.h>
> #include <linux/slab.h>
> #include <linux/suspend.h>
> +#include <linux/delay.h>
> #include <asm/unaligned.h>
>
> #ifdef CONFIG_ACPI_PROCFS_POWER
> @@ -1119,7 +1120,7 @@ static struct dmi_system_id bat_dmi_table[] = {
>
> static int acpi_battery_add(struct acpi_device *device)
> {
> - int result = 0;
> + int result = 0, retry = 5;
> struct acpi_battery *battery = NULL;
>
> if (!device)
> @@ -1135,7 +1136,16 @@ static int acpi_battery_add(struct acpi_device *device)
> mutex_init(&battery->sysfs_lock);
> if (acpi_has_method(battery->device->handle, "_BIX"))
> set_bit(ACPI_BATTERY_XINFO_PRESENT, &battery->flags);
> +
> +retry_get_info:
> result = acpi_battery_update(battery, false);
> +
> + if (result && retry) {
> + msleep(20);

We're really going to wait up to 20 * 5 = 100ms for acpi_battery_update()
to succeed? How are these the numbers that are determined to be optimal
for probing?

> + retry--;
> + goto retry_get_info;
> + }

This most certainly could be rewritten as a for-loop and remove the ugly
goto.

> +
> if (result)
> goto fail;
> #ifdef CONFIG_ACPI_PROCFS_POWER


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