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@xxxxx> > >> Reference: https://bugzilla.kernel.org/show_bug.cgi?id=75581 > >> Cc: stable@xxxxxxxxxxxxxxx > >> Signed-off-by: Lan Tianyu <tianyu.lan@xxxxxxxxx> > >> --- > >> 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); > > > > Hi David: > Thanks for review. > > > We're really going to wait up to 20 * 5 = 100ms for acpi_battery_update() > > to succeed? > > No, this depends which retry acpi_battery_update() will succeed. For > most machines, there will be no delay. > Right, but you're willing to wait up to 100ms for it to succeed? You're implementing x retries with y ms sleep in between, I'm asking how it is determined that the optimal values are x = 5 and y = 20. More directly: is it possible to succeed at 101ms? Is it really likely to succeed after the first 20ms? -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
