From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: "Fix ATAPI transfer lengths" causes CD writing regression Date: Wed, 31 Oct 2007 08:20:06 -0400 Message-ID: <472872F6.70802@garzik.org> References: <47274A5F.6070409@gentoo.org> <20071030153417.59b9182c@the-village.bc.nu> <47276DCA.1000808@gentoo.org> <20071030190153.373c9347@the-village.bc.nu> <47278439.4030801@gentoo.org> <20071031114958.210bd7cc@the-village.bc.nu> <20071031115754.GK5059@kernel.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:54386 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755235AbXJaMUS (ORCPT ); Wed, 31 Oct 2007 08:20:18 -0400 In-Reply-To: <20071031115754.GK5059@kernel.dk> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Jens Axboe Cc: Alan Cox , Daniel Drake , linux list , linux-ide@vger.kernel.org Jens Axboe wrote: > On Wed, Oct 31 2007, Alan Cox wrote: >> On Tue, 30 Oct 2007 19:21:29 +0000 >> Daniel Drake wrote: >> >>> Alan Cox wrote: >>>> I would guess Brasero is issuing a command with the length of data >>>> wrongly set. In the old code that might well just produce errors of the >>>> "Umm wtf is this data left over for ?", with the new code the drive is >>>> likely to change state as it knows the transfer size and that will >>>> *correctly* cause an HSM error and what follows. >>>> >>>> Now the question is who gets the length wrong - Brasero or the ata >>>> translation code in libata >>> Brasero does exactly the same as my test app which I attached to my last >>> mail. Is my test app wrong? >> Would need to double check the SCSI specificatons to be sure but I think >> you are asking for less data than the drive wishes to provide. You >> aren't allowed to do that with ATA. > > ide-cd handles this by throwing the excess away, which I think is the > sane way to do this. That's easy for the PIO case. But CD writing is normally DMA, which means you will get a DMA engine exception if the device wants to give you more data than the scatter/gather entries permit. Jeff