Return-path: Received: from smtp.nokia.com ([147.243.1.48]:26764 "EHLO mgw-sa02.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753140Ab1BHLY4 (ORCPT ); Tue, 8 Feb 2011 06:24:56 -0500 Received: from nokia.com (localhost [127.0.0.1]) by mgw-sa02.nokia.com (Switch-3.4.3/Switch-3.4.3) with ESMTP id p18BOsLl015468 for ; Tue, 8 Feb 2011 13:24:54 +0200 Subject: Re: [RFC PATCH] wl12xx: Change claiming of the (SDIO) bus From: Juuso Oikarinen To: linux-wireless@vger.kernel.org Cc: luciano.coelho@nokia.com In-Reply-To: <1297058902.4035.69.camel@wimaxnb.nmp.nokia.com> References: <1296819336-8373-1-git-send-email-juuso.oikarinen@nokia.com> <1297058902.4035.69.camel@wimaxnb.nmp.nokia.com> Content-Type: text/plain; charset="UTF-8" Date: Tue, 08 Feb 2011 13:24:42 +0200 Message-ID: <1297164282.3389.10.camel@wimaxnb.nmp.nokia.com> Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Mon, 2011-02-07 at 08:08 +0200, ext Juuso Oikarinen wrote: > On Fri, 2011-02-04 at 13:35 +0200, ext juuso.oikarinen@nokia.com wrote: > > From: Juuso Oikarinen > > > > Currently, the SDIO bus is claimed separately for each and every SDIO > > transaction - i.e. every register write/read etc. > > > > The SDIO claiming is a relatively heavy operation. In a worst case scenario, > > it will put the SDIO bus on suspend, stop relevant clocks etc which all can be > > extremely costly if done between each SDIO transaction. This has a dramatic > > impact on the maximum throughput achieved. > > > > The driver already manages its access to the bus as it needs to manage > > chipset ELP. This mechanism disables ELP for the duration of the whole bus > > access, consisting of multiple transactions. > > > > Into the IO layer, this patch implements a claim/unclaim function, which is > > used to claim access to the bus. Relevant functions are checked and updated to > > maintain correctly the claim reference counter, so that each claim is paired > > with a corresponding unclaim. > > > > For PLT and ad-hoc modes the bus is kept claimed contantly. > > > > For AP mode, this patch brings no change to the previous way of working, > > someone familiar with it and with the ability to test it may implement > > something similar as is done here for the other modes. > > > > For the SPI bus, the claim/unclaim functions are not implemented, i.e. no > > change to functionality. > > > > Signed-off-by: Juuso Oikarinen > > --- > > I realised there are two separate issues here in one patch. I'll need to > split this into two patches. Also, there are some other issues I need to > address. > I'm dropping this patch. In the end our measurements didn't indicate any drastic benefits of this change, so its not worth contemplating more about it. -Juuso