From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robert Hancock Subject: Re: [PATCH] sata_nv: fix ADMA ATAPI issues with memory over 4GB (v2) Date: Thu, 22 Nov 2007 19:01:39 -0600 Message-ID: <47462673.3080701@shaw.ca> References: <47438248.7030704@shaw.ca> <4745234E.9050409@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from idcmail-mo1so.shaw.ca ([24.71.223.10]:26702 "EHLO pd2mo1so.prod.shaw.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751767AbXKWBBn (ORCPT ); Thu, 22 Nov 2007 20:01:43 -0500 In-reply-to: <4745234E.9050409@gmail.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Tejun Heo Cc: linux-kernel , ide , Jeff Garzik Tejun Heo wrote: > Hello, Robert. > > Robert Hancock wrote: >> This fixes some problems with ATAPI devices on nForce4 controllers in ADMA >> mode on systems with memory located above 4GB. We need to delay setting the >> 64-bit DMA mask until the PRD table and padding buffer are allocated so that >> they don't get allocated above 4GB and break legacy mode (which is needed for >> ATAPI devices). Also, explicitly set a 32-bit DMA mask before allocating the >> legacy buffers since setting the DMA mask affects both ports and we need to >> ensure the second port's buffers are allocated properly (fixes a problem >> with the previous version of this patch). >> >> Signed-off-by: Robert Hancock >> >> + /* Ensure DMA mask is set to 32-bit before allocating legacy PRD and >> + pad buffers */ >> + pci_set_dma_mask(pdev, DMA_BIT_MASK(32)); >> + pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(32)); > [--snip--] >> + pci_set_dma_mask(pdev, DMA_BIT_MASK(64)); >> + pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(64)); > > I'm probably being paranoid here but please add error checks. Just > checking return value and returning error suffices. In the 32-bit case, I'm pretty sure those are guaranteed not to fail because 32-bit is the default. For the 64-bit ones, we don't care if they fail, because then we'll just use whatever mask ends up being set (we store the actual set DMA mask in adma_dma_mask for use when we need to reconfigure the bounce limit). We definitely don't want to fail initialization if the 64-bit set doesn't succeed..