From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alan Cox Subject: Re: [PATCH 09/15] libata: implement ata_down_xfermask_limit() Date: Fri, 31 Mar 2006 23:31:32 +0100 Message-ID: <1143844292.15646.4.camel@localhost.localdomain> References: <11438230983159-git-send-email-htejun@gmail.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from outpipe-village-512-1.bc.nu ([81.2.110.250]:3003 "EHLO lxorguk.ukuu.org.uk") by vger.kernel.org with ESMTP id S1751452AbWCaWYS (ORCPT ); Fri, 31 Mar 2006 17:24:18 -0500 In-Reply-To: <11438230983159-git-send-email-htejun@gmail.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Tejun Heo Cc: jgarzik@pobox.com, albertcc@tw.ibm.com, linux-ide@vger.kernel.org On Sad, 2006-04-01 at 01:38 +0900, Tejun Heo wrote: > Implement ata_down_xfermask_limit(). This function manipulates > @dev->pio/mwdma/udma_mask such that the next lower transfer mode is > selected. This will be used by ata_bus_probe() rewrite and later by > EH speeding down. This will need care. If it is called during a transfer mode change on error we should document that this function will only be called after the host_set has been quiesced, otherwise drivers that peek a lot at their ap-> mode settings at runtime (eg on an IRQ occuring during a speed change down) are going to burned badly. It would be nice to see a description of the locking model for a changedown at this point. Alan