From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Lord Subject: Re: [PATCH 1/3] Make the IDE DMA timeout modifiable Date: Fri, 13 Jul 2007 15:36:05 -0400 Message-ID: <4697D425.7000300@rtr.ca> References: <20070221011922.GA1777@freefall.freebsd.org> <200702210342.20775.bzolnier@gmail.com> <466EEFD6.9030001@ru.mvista.com> <200706160123.55636.bzolnier@gmail.com> <4693D9B6.4090408@ru.mvista.com> <20070713161612.2f2ebb0b@the-village.bc.nu> <46979652.6040201@rtr.ca> <4697987E.3040406@ru.mvista.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from rtr.ca ([64.26.128.89]:2675 "EHLO mail.rtr.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759357AbXGMTgI (ORCPT ); Fri, 13 Jul 2007 15:36:08 -0400 In-Reply-To: <4697987E.3040406@ru.mvista.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Sergei Shtylyov Cc: Alan Cox , Bartlomiej Zolnierkiewicz , Suleiman Souhlal , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org Sergei Shtylyov wrote: > Mark Lord wrote: > >>> O> >> BTW, why the timeout is so damn long? 2*WAIT_CMD is 20 secs, >>> and if DMA is not complete or interrupt pending, it may wait 10 more secs... .. >> I've lost the original question from this thread, but the idea of the > > The original question concerned specifically the DMA command timeout > which is twice more than the usual one, WAIT_CMD (10 seconds). > >> longish >> timeouts was that drive *may* be spun down ("standby"), and thus have >> to spin >> up again to complete media commands. Back then, drives were much >> slower at >> spinning up than nowadays, and the ATA spec says to allow up to 30 >> seconds. > > Well, that doesn't explain the DMA case. When a drive is in standby, we don't send it anything special to wake up. So even DMA commands have to have a long enough timeout to allow for spinning up. Cheers