linux-kernel - Re: [PATCH] ACPI/Battery: Retry to get Battery information if failed during probing

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Message-ID: <539E528B.90908@intel.com>
Date:	Mon, 16 Jun 2014 10:12:27 +0800
From:	Lan Tianyu <tianyu.lan@...el.com>
To:	David Rientjes <rientjes@...gle.com>
CC:	rjw@...ysocki.net, lenb@...nel.org, naszar@...ru,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ACPI/Battery: Retry to get Battery information if failed
 during probing

On 2014年06月14日 05:46, David Rientjes wrote:
> On Fri, 13 Jun 2014, Lan Tianyu wrote:
> 
>> How about this?
>>
>> -       result = acpi_battery_update(battery, false);
>> -       if (result)
>> +
>> +       /*
>> +        * Some machines'(E,G Lenovo Z480) ECs are not stable
>> +        * during boot up and this causes battery driver fails to be
>> +        * probed due to failure of getting battery information
>> +        * from EC sometimes. After several retries, the operation
>> +        * may work. So add retry code here and 20ms sleep between
>> +        * every retries.
>> +        */
>> +       while (acpi_battery_update(battery, false) && retry--)
>> +               msleep(20);
>> +       if (!retry) {
>> +               result = -ENODEV;
>>                 goto fail;
>> +       }
>> +
> 
> I think you want --retry and not retry--.

My original purpose is to retry 5 times after the first try fails.
If use "--retry" here, it just retries 4 times.

>  Otherwise it's possible for the 
> final call to acpi_battery_update() to succeed and now it's returning 
> -ENODEV.
> 

Yes, it maybe and I will change code like the following.

while ((result = acpi_battery_update(battery, false)) && retry--)
       msleep(20);
if (result)
       goto fail;


-- 
Best regards
Tianyu Lan
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