linux-kernel - Re: [PATCH] ACPI: full battery charge cannot exceed current one

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Message-ID: <20131209170214.GB30717@srcf.ucam.org>
Date:	Mon, 9 Dec 2013 17:02:14 +0000
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	Jan Vcelak <jan.vcelak@....cz>
Cc:	lenb@...nel.org, rjw@...ysocki.net, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ACPI: full battery charge cannot exceed current one

On Sat, Dec 07, 2013 at 01:36:41PM +0100, Jan Vcelak wrote:
> Some degraded batteries report maximal capacity to be smaller than
> current charge of the battery. This can confuse some user space
> applications (like upower).

Can't we just fix upower?

> +
> +	/* Some degraded batteries report lower full charge than current one. */
> +	if (battery->capacity_now > battery->full_charge_capacity)
> +		battery->full_charge_capacity = battery->capacity_now;
> +

Does upower read *_full on every read of the value? How do we guarantee 
that it won't read energy_now without updating energy_full and still 
come up with an incorrect calculation?

-- 
Matthew Garrett | mjg59@...f.ucam.org
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