From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Dooks Date: Wed, 29 Jan 2014 08:03:00 +0000 Subject: Re: [PATCH RFC 0/2] ARM: shmobile: lager: Enable DMA bounce for PCI Message-Id: <52E8B5B4.6060800@codethink.co.uk> List-Id: References: <1390935213-12896-1-git-send-email-valentine.barshak@cogentembedded.com> In-Reply-To: <1390935213-12896-1-git-send-email-valentine.barshak@cogentembedded.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-sh@vger.kernel.org On 29/01/14 06:45, Simon Horman wrote: > On Tue, Jan 28, 2014 at 10:53:31PM +0400, Valentine Barshak wrote: >> This enables DMA bounce for PCI since the controller does >> not support more than 2G PCI-AHB memory window. >> The problems with DMA transfers can be observed when >> setting 2G/2G user/kernel memory split model >> (CONFIG_VMSPLIT_2G=y) >> These patches help to avoid it. > > Are these patches compatible with other user/kernel splits? PS, the bridge is only actually capable of seeing 1GiB of RAM due to alignment issues in the window. You can have either 0x4..0x8 or 0x8..0xc but not /both/. If you open the window to 2GiB then you can see either 0x0..0x8 or 0x8..0xF range. -- Ben Dooks http://www.codethink.co.uk/ Senior Engineer Codethink - Providing Genius