From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from moutng.kundenserver.de ([212.227.126.130]:65011 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753220AbaBYPoc (ORCPT ); Tue, 25 Feb 2014 10:44:32 -0500 From: Arnd Bergmann To: Magnus Damm Subject: Re: DMABOUNCE in pci-rcar Date: Tue, 25 Feb 2014 16:44:01 +0100 Cc: "Russell King - ARM Linux" , Magnus Damm , linux-pci@vger.kernel.org, Simon Horman , "linux-kernel" , Bjorn Helgaas , "linux-arm-kernel@lists.infradead.org" , "SH-Linux" , Ben Dooks , Santosh Shilimkar References: <201402241200.21944.arnd@arndb.de> <20140225001748.GS21483@n2100.arm.linux.org.uk> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Message-Id: <201402251644.01463.arnd@arndb.de> Sender: linux-pci-owner@vger.kernel.org List-ID: On Tuesday 25 February 2014, Magnus Damm wrote: > And the DMABOUNCE code does not support HIGHMEM, so because of that > the block layer BOUNCE is also used. Ah, I misunderstood this part previously. I understand better what's going on now, but this also enforces the impression that both BOUNCE and DMABOUNCE are not what you should be doing here. On a related note, I've had some more discussions with Santosh on IRC, and I think he's in the exact same position on mach-keystone, so we should make sure that whatever solution either of you comes up with also works for the other one. The situation on keystone may be a little worse even, because all their DMA masters have a 2GB limit, but it's also possible that the same is true for you. Which categories of DMA masters do you have on R-Car? a) less than 32-bit mask, with IOMMU b) less than 32-bit mask, without IOMMU c) 32-bit mask d) 64-bit mask Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Date: Tue, 25 Feb 2014 15:44:01 +0000 Subject: Re: DMABOUNCE in pci-rcar Message-Id: <201402251644.01463.arnd@arndb.de> List-Id: References: <201402241200.21944.arnd@arndb.de> <20140225001748.GS21483@n2100.arm.linux.org.uk> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-arm-kernel@lists.infradead.org On Tuesday 25 February 2014, Magnus Damm wrote: > And the DMABOUNCE code does not support HIGHMEM, so because of that > the block layer BOUNCE is also used. Ah, I misunderstood this part previously. I understand better what's going on now, but this also enforces the impression that both BOUNCE and DMABOUNCE are not what you should be doing here. On a related note, I've had some more discussions with Santosh on IRC, and I think he's in the exact same position on mach-keystone, so we should make sure that whatever solution either of you comes up with also works for the other one. The situation on keystone may be a little worse even, because all their DMA masters have a 2GB limit, but it's also possible that the same is true for you. Which categories of DMA masters do you have on R-Car? a) less than 32-bit mask, with IOMMU b) less than 32-bit mask, without IOMMU c) 32-bit mask d) 64-bit mask Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Tue, 25 Feb 2014 16:44:01 +0100 Subject: DMABOUNCE in pci-rcar In-Reply-To: References: <201402241200.21944.arnd@arndb.de> <20140225001748.GS21483@n2100.arm.linux.org.uk> Message-ID: <201402251644.01463.arnd@arndb.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tuesday 25 February 2014, Magnus Damm wrote: > And the DMABOUNCE code does not support HIGHMEM, so because of that > the block layer BOUNCE is also used. Ah, I misunderstood this part previously. I understand better what's going on now, but this also enforces the impression that both BOUNCE and DMABOUNCE are not what you should be doing here. On a related note, I've had some more discussions with Santosh on IRC, and I think he's in the exact same position on mach-keystone, so we should make sure that whatever solution either of you comes up with also works for the other one. The situation on keystone may be a little worse even, because all their DMA masters have a 2GB limit, but it's also possible that the same is true for you. Which categories of DMA masters do you have on R-Car? a) less than 32-bit mask, with IOMMU b) less than 32-bit mask, without IOMMU c) 32-bit mask d) 64-bit mask Arnd