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 14:16:43 +0900 Message-ID: <4747B3BB.4000708@gmail.com> References: <47463580.8080909@shaw.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from wa-out-1112.google.com ([209.85.146.183]:22550 "EHLO wa-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750741AbXKXFQu (ORCPT ); Sat, 24 Nov 2007 00:16:50 -0500 Received: by wa-out-1112.google.com with SMTP id v27so35483wah for ; Fri, 23 Nov 2007 21:16:50 -0800 (PST) In-Reply-To: <47463580.8080909@shaw.ca> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Robert Hancock Cc: linux-kernel , ide , Jeff Garzik 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). Sorry. :-) -- tejun