Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753325AbbBXO2q (ORCPT ); Tue, 24 Feb 2015 09:28:46 -0500 Received: from pandora.arm.linux.org.uk ([78.32.30.218]:60402 "EHLO pandora.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752387AbbBXO2o (ORCPT ); Tue, 24 Feb 2015 09:28:44 -0500 Date: Tue, 24 Feb 2015 14:28:33 +0000 From: Russell King - ARM Linux To: Peter Ujfalusi Cc: vinod.koul@intel.com, Tony Lindgren , grant.likely@linaro.org, dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, robh+dt@kernel.org, nm@ti.com Subject: Re: [PATCH 5/6] dmaengine: omap-dma: Remove mapping between virtual channels and requests 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 Content-Disposition: inline In-Reply-To: <1424787683-19151-6-git-send-email-peter.ujfalusi@ti.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1078 Lines: 24 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 linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/