From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Gordon Subject: Re: [PATCH v2 4/7] scatterlist: add sg_alloc_table_from_buf() helper Date: Tue, 5 Apr 2016 08:11:48 +0100 Message-ID: <57036534.7010800@intel.com> References: <1459352394-22810-1-git-send-email-boris.brezillon@free-electrons.com> <1459352394-22810-5-git-send-email-boris.brezillon@free-electrons.com> <20160330165143.GI2350@sirena.org.uk> <20160330201831.38e1d6bd@bbrezillon> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160330201831.38e1d6bd@bbrezillon> Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Boris Brezillon , Mark Brown Cc: David Woodhouse , Brian Norris , linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Andrew Morton , linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Maxime Ripard , Chen-Yu Tsai , linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org, Vinod Koul , Dan Williams , dmaengine-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Mauro Carvalho Chehab , Hans Verkuil , Laurent Pinchart , linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Richard Weinberger List-Id: devicetree@vger.kernel.org On 30/03/16 19:18, Boris Brezillon wrote: > On Wed, 30 Mar 2016 09:51:43 -0700 > Mark Brown wrote: > >> On Wed, Mar 30, 2016 at 05:39:51PM +0200, Boris Brezillon wrote: >>> sg_alloc_table_from_buf() provides an easy solution to create an sg_table >>> from a virtual address pointer. This function takes care of dealing with >>> vmallocated buffers, buffer alignment, or DMA engine limitations (maximum >>> DMA transfer size). >> >> This seems nice. Should we also have a further helper on top of this >> which will get constraints from a dmaengine, it seems like it'd be a >> common need? > > Yep, we could create a wrapper extracting dma_slave caps info, > converting it to sg_constraints and calling sg_alloc_table_from_buf(). > But let's try to get this function accepted first, and I'll send another > patch providing this wrapper. > > BTW, do you see other things that should be added in sg_constraints? > You could compare with the things Solaris uses to describe the restrictions on a DMA binding ... http://docs.oracle.com/cd/E23824_01/html/821-1478/ddi-dma-attr-9s.html#REFMAN9Sddi-dma-attr-9s .Dave. -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html