From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexey Starikovskiy Subject: Re: [PATCH] 2.6.24-rc1: ensure "present" sysfs attribute even if battery is absent Date: Sat, 27 Oct 2007 22:18:14 +0400 Message-ID: <472380E6.10304@gmail.com> References: <200710272054.31160.arvidjaar@mail.ru> <47237255.9020001@gmail.com> <200710272150.29596.arvidjaar@mail.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from ug-out-1314.google.com ([66.249.92.170]:23843 "EHLO ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750884AbXJ0SSj (ORCPT ); Sat, 27 Oct 2007 14:18:39 -0400 Received: by ug-out-1314.google.com with SMTP id z38so820717ugc for ; Sat, 27 Oct 2007 11:18:37 -0700 (PDT) In-Reply-To: <200710272150.29596.arvidjaar@mail.ru> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Andrey Borzenkov Cc: linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, cbou@mail.ru, dwmw2@infradead.org Andrey Borzenkov wrote: > On Saturday 27 October 2007, Alexey Starikovskiy wrote: >> Andrey Borzenkov wrote: >>> I am not exactly sure about this one ... what other power_supply class >>> drivers do? Should I fix HAL instead (but then, I do not know whether HAL >>> is the only application that is using this interface). >> Hm, do you need separate set of properties for that? You could register >> either of existing two, and read function will not allow read of anything >> but "present". IMHO, this is what other modules do (/drivers/power) > > Do they have different set of properties depending on underlying hardware that > you can't query unless hardware is present? I'd rather avoid adding fake > attributes; but I do not actually care so which one do you prefer? :) I prefer less code :) > >> One remaining trick here, you need to call unregister/register for >> power_supply if you change attributes -- so please check if your patched >> driver survives insertion of the battery. >> > > > Neither does your code (nor kpowersave :) ) Remove battery and set of > attributes is "stuck" instead of being reset to only fixed set of power > device attributes (basically "info"). The only call to power_supply_register > is in acpi_battery_add and as far as I can tell this is executed on adding > *slot* not when content of this slot changes. Point is -- it does not break :) If you start to play with shorter length of attributes table and don't call unregister/register, power_supply may go past the end of table.