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

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Date:	Mon, 16 Jun 2014 10:43:31 +0800
From:	Lan Tianyu <tianyu.lan@...el.com>
To:	"Zheng, Lv" <lv.zheng@...el.com>
CC:	David Rientjes <rientjes@...gle.com>,
	"rjw@...ysocki.net" <rjw@...ysocki.net>,
	"lenb@...nel.org" <lenb@...nel.org>, "naszar@...ru" <naszar@...ru>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-kernel@...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16日 10:35, Zheng, Lv wrote:
> Hi,
> 
>> From: linux-acpi-owner@...r.kernel.org [mailto:linux-acpi-owner@...r.kernel.org] On Behalf Of Lan Tianyu
>> Sent: Monday, June 16, 2014 10:12 AM
>> To: David Rientjes
>> 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
> 
> Just a reminder.
> 
> This statement may not be true.
> The issue may be caused by the EC driver itself.
> So we need to investigate.

Not sure. The bug doesn't happen every time. 5-10% during boot up.

> 
>>>> +        * 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--)
> 
> If EC hardware is stable, why we need to do retry here?
> 

Yes, if it can work normally every time, we don't need retry here.


> Thanks and best regards
> -Lv
> 
>>>> +               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
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
>> the body of a message to majordomo@...r.kernel.org
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-- 
Best regards
Tianyu Lan
--
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