From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Ball Subject: Re: [PATCH] Revert "mmc: dw_mmc: Add check for IDMAC configuration" Date: Wed, 19 Sep 2012 02:03:26 -0400 Message-ID: References: <00d801cd8fc4$738f8540$5aae8fc0$%jun@samsung.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from void.printf.net ([89.145.121.20]:53510 "EHLO void.printf.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754157Ab2ISGDG (ORCPT ); Wed, 19 Sep 2012 02:03:06 -0400 In-Reply-To: (Will Newton's message of "Mon, 17 Sep 2012 12:15:46 +0100") Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Will Newton Cc: Seungwon Jeon , linux-mmc@vger.kernel.org, girish.shivananjappa@linaro.org, James Hogan Hi, On Mon, Sep 17 2012, Will Newton wrote: > On Tue, Sep 11, 2012 at 3:23 AM, Seungwon Jeon wrote: >> This reverts commit 94c6cee91(Add check for IDMAC configuration). >> Synopsys says that only if internal dmac is not present, optional >> external dma interface is present. When internal dmac is present, >> '0' value in DMA_INTERFACE of HCON is reasonable. DMA_INTERFACE >> indicates external dma interface. And idmac initialization is >> prohibited now. So, let's revert this commit. >> >> CC: Girish K S >> Signed-off-by: Seungwon Jeon >> --- >> drivers/mmc/host/dw_mmc.c | 15 ++------------- >> 1 files changed, 2 insertions(+), 13 deletions(-) > > I think this revert is a good idea. The original patch tries to check > whether IDMAC is supported and falls back to PIO, but it is not clear > to me that HCON gives you the appropriate information to do this (at > least in my version of the manual, I have not tried to clarify this > with Synopsys). Also falling back to PIO mode seems like it would > provide pretty awful performance, I would not expect to see instances > of this block with no DMA support anywhere other than FPGA so > configuring with IDMAC without it's presence would be a serious > misconfiguration in any case. > > Acked-by: Will Newton Thanks, pushed to mmc-next for 3.7. - Chris. -- Chris Ball One Laptop Per Child