From mboxrd@z Thu Jan 1 00:00:00 1970 From: viresh kumar Subject: [QUERY] amba/pl022: DMA channel allocation always fail. Date: Fri, 13 May 2011 17:31:04 +0530 Message-ID: <4DCD1D80.7060409@st.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Armando VISCONTI , Shiraz HASHIM To: "linus.walleij-0IS4wlFg1OjSUeElwK9/Pw@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Return-path: 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 Linus, amba/pl022 and my dma driver dw_dmac.c, both have registered init() routines with subsys_initcall(). Now at bootup, spi boots up before DMA and so DMA channels are never available at spi probe. What should be done to solve this issue? One idea is allocate DMA channel as and when required, instead of allocating them at probe. But in that case too i am not sure, that this issue will be solved. As, if spi slave device is added from board file, then it will also try to transfer data as soon as spi driver is up. So that too may be called before dma_probe(). -- viresh ------------------------------------------------------------------------------ Achieve unprecedented app performance and reliability What every C/C++ and Fortran developer should know. Learn how Intel has extended the reach of its next-generation tools to help boost performance applications - inlcuding clusters. http://p.sf.net/sfu/intel-dev2devmay