Date: Fri, 13 Jun 2014 14:46:11 -0700 (PDT)
From: David Rientjes <rientjes@google.com>
To: Lan Tianyu <tianyu.lan@intel.com>
cc: rjw@rjwysocki.net, lenb@kernel.org, naszar@ya.ru,
        linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org,
        stable@vger.kernel.org
Subject: Re: [PATCH] ACPI/Battery: Retry to get Battery information if failed
 during probing
In-Reply-To: <539A60FC.1050301@intel.com>
Message-ID: <alpine.DEB.2.02.1406131445130.31981@chino.kir.corp.google.com>
References: <1402552946-14704-1-git-send-email-tianyu.lan@intel.com> <alpine.DEB.2.02.1406112354070.23724@chino.kir.corp.google.com> <53995488.20308@intel.com> <alpine.DEB.2.02.1406120025050.23724@chino.kir.corp.google.com> <53996152.2000407@intel.com>
 <alpine.DEB.2.02.1406121415150.8305@chino.kir.corp.google.com> <539A60FC.1050301@intel.com>
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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--.  Otherwise it's possible for the 
final call to acpi_battery_update() to succeed and now it's returning 
-ENODEV.
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