From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?B?SmFuIFbEjWVsw6Fr?= Subject: Re: [PATCH] ACPI: full battery charge cannot exceed current one Date: Mon, 09 Dec 2013 23:25:15 +0100 Message-ID: <52A6434B.9040100@nic.cz> References: <1386419801-10091-1-git-send-email-jan.vcelak@nic.cz> <20131209170214.GB30717@srcf.ucam.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mail.nic.cz ([217.31.204.67]:46105 "EHLO mail.nic.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753214Ab3LIWZU (ORCPT ); Mon, 9 Dec 2013 17:25:20 -0500 In-Reply-To: <20131209170214.GB30717@srcf.ucam.org> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Matthew Garrett Cc: lenb@kernel.org, rjw@rjwysocki.net, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org >> 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? It looks like upower already resolved that: http://cgit.freedesktop.org/upower/tree/src/linux/up-device-supply.c#n652 If the purpose of sysfs is to provide raw values retrieved from battery, then I agree that this should not be handled in kernel. Otherwise I would expect semantically correct data there. >> + /* 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? That's a good point. I'm not sure about other applications, but upower always refreshes all values. Function up_device_supply_refresh_battery seems to be the only place where 'charge_now' is being read: http://cgit.freedesktop.org/upower/tree/src/linux/up-device-supply.c#n485