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

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Message-ID: <alpine.DEB.2.02.1406161827320.21018@chino.kir.corp.google.com>
Date:	Mon, 16 Jun 2014 18:27:54 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Lan Tianyu <tianyu.lan@...el.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 Mon, 16 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;
> 

Looks good.
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