From mboxrd@z Thu Jan 1 00:00:00 1970 From: Angelo Dureghello Subject: Re: [PATCH] mmc: davinci_mmc: add warnings for edma failures Date: Thu, 27 Nov 2014 11:18:48 +0100 Message-ID: <5476FA88.6070105@sysam.it> References: <546FD21C.7010208@sysam.it> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from sysam.it ([5.39.81.93]:38057 "EHLO mail.sysam.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753346AbaK0KTe (ORCPT ); Thu, 27 Nov 2014 05:19:34 -0500 In-Reply-To: Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: linux-mmc@vger.kernel.org Cc: Ulf Hansson Hi Uffe, many hanks for the reply, >> Add warnings in case the edma engine driver fails to allocate slots or >> channels requested from the davinci_mmc driver. >> >> Some ti-davinci based boards (i.e. board-da850-evm.c) are asking for >> some reserved chans / slots at board init stage. Later, the mmc driver >> results in a silent locked state. > > So why does davinci_acquire_dma_channels() succeed then? Isn't that > real problem you should be looking into? i explain with more details, my custom am1808 board initialization, based on arch/arm/mach-davinci/board-da850-evm.c, reserves some dma chans / slots for the audio at early boot. While on kernel 3.5.1 mmc was working properly, moving to kernel 3.17.0, due to the dma-engine wrapper introduction (to be selected into menuconfig), the mmc host driver locks silently. System cannot even "reboot" after the failed attempt to reserve the dma slots. I hardly found out the reason due to missing of clear warnings. So there is nothing to fix in any other place. Simply, i am suggesting a more visible warning so the driver, instead of lock-up silently, throws a problem. Feel free to add or discard the patch, as you can see it is nothing functional. Regards, Angelo