From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH] sata_nv: don't use legacy DMA in ADMA mode (v2) Date: Sat, 24 Nov 2007 14:19:38 +0900 Message-ID: <4747B46A.5000503@gmail.com> References: <47463580.8080909@shaw.ca> <4747B3BB.4000708@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from rv-out-0910.google.com ([209.85.198.186]:43217 "EHLO rv-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751327AbXKXFTp (ORCPT ); Sat, 24 Nov 2007 00:19:45 -0500 Received: by rv-out-0910.google.com with SMTP id k20so30241rvb for ; Fri, 23 Nov 2007 21:19:44 -0800 (PST) In-Reply-To: <4747B3BB.4000708@gmail.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Robert Hancock Cc: linux-kernel , ide , Jeff Garzik Tejun Heo wrote: > Robert Hancock wrote: >> We need to run any DMA command with result taskfile requested in ADMA mode >> when the port is in ADMA mode, otherwise it may try to use the legacy DMA engine >> in ADMA mode which is not allowed. Enforce this with BUG_ON() since data >> corruption could potentially result if this happened. Also WARN_ON() if we try >> and send result taskfile commands while NCQ commands are still active, since the >> hardware doesn't allow this. >> >> Signed-off-by: Robert Hancock >> >> @@ -1425,9 +1427,17 @@ >> + /* We can't handle result taskfile with NCQ commands active, since >> + retrieving the taskfile switches us out of ADMA mode and would abort >> + existing commands. */ >> + WARN_ON((qc->flags & ATA_QCFLAG_RESULT_TF) && >> + (qc->ap->qc_allocated & ~(1 << qc->tag))); > > I owe an apology here. ap->qc_allocated & ~(1 << qc->tag) test isn't > correct. Sorry. qc deferring happens after qc is allocated so the > condition can trigger (although it should be rare) even when nothing is > going wrong, so I guess it should be WARN_ON((qc->flags & > ATA_QCFLAG_RESULT_TF) && link->sactive). Or, just make the assumption clear by not allowing NCQ w/ RESULT_TF at all. if (unlikely(qc->tf.protocol == ATA_PROT_NCQ && (qc->flags & ATA_QCFLAG_RESULT_TF)) { ata_dev_printk(qc->dev, KERN_ERR, "NCQ w/ RESULT_TF not allowed\n"); return AC_ERR_SYSTEM; } Thanks. -- tejun