From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Dooks Subject: Re: atmel_spi: DMA-imposed xfer buffer requirements Date: Mon, 20 Oct 2008 18:02:48 +0100 Message-ID: <20081020170248.GB14806@trinity.fluff.org> References: <106f03a70810200856q4af97370h6cd456f3a42d70e5@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, Haavard Skinnemoen To: Andrei Rylin Return-path: Content-Disposition: inline In-Reply-To: <106f03a70810200856q4af97370h6cd456f3a42d70e5-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: spi-devel-general-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-spi.vger.kernel.org On Mon, Oct 20, 2008 at 08:56:41AM -0700, Andrei Rylin wrote: > Haavard, > thanks for clarification about cs_change. > I have another (hopefully last) question about atmel_spi driver. > atmel_spi driver DMA-maps the buffers pointed to by spi_transfer. > What are alignment and size requirements for the buffers ? > How to expressed them in a platform-independent way, > i.e. suitable for use with other SPI master drivers ? > Can the buffers be in stack ? Or do they always have to be > allocated from a non-paged pool ? no, I belive no linux arch allows dma to/from the stack. dma_alloc_xxx() and friends are your best bet for allocating such memory. > Thanks, > Andrei. > > ------------------------------------------------------------------------- > This SF.Net email is sponsored by the Moblin Your Move Developer's challenge > Build the coolest Linux based applications with Moblin SDK & win great prizes > Grand prize is a trip for two to an Open Source event anywhere in the world > http://moblin-contest.org/redirect.php?banner_id=100&url=/ > _______________________________________________ > spi-devel-general mailing list > spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org > https://lists.sourceforge.net/lists/listinfo/spi-devel-general -- -- Ben Q: What's a light-year? A: One-third less calories than a regular year. ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/