From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King - ARM Linux Subject: Re: [PATCH 5/6] dmaengine: omap-dma: Remove mapping between virtual channels and requests Date: Tue, 24 Feb 2015 14:28:33 +0000 Message-ID: <20150224142833.GI8670@n2100.arm.linux.org.uk> References: <1424787683-19151-1-git-send-email-peter.ujfalusi@ti.com> <1424787683-19151-6-git-send-email-peter.ujfalusi@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1424787683-19151-6-git-send-email-peter.ujfalusi-l0cyMroinI0@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Peter Ujfalusi Cc: vinod.koul-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, Tony Lindgren , grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, dmaengine-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, nm-l0cyMroinI0@public.gmane.org List-Id: devicetree@vger.kernel.org On Tue, Feb 24, 2015 at 04:21:22PM +0200, Peter Ujfalusi wrote: > Do not direct map the virtual channels to sDMA request number. When the > sDMA is behind of a crossbar this direct mapping can cause situations when > certain channel can not be requested since the crossbar request number > will no longer match with the sDMA request line. > The direct mapping for virtual channels with HW request lines will make it > harder to implement MEM_TO_MEM mode for the driver. I assume when you talk about MEM_TO_MEM, you're referring to a DMA_MEMCPY driver. mem2mem should not be handled by the slave driver. This should be a separate DMA engine driver structure which does not have DMA_SLAVE set. See how amba-pl08x handles this. -- FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html