From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kevin Hilman Subject: Re: [PATCH] OMAP2/3/4: DMA: reset controller during init Date: Mon, 03 May 2010 09:03:18 -0700 Message-ID: <87zl0h6khl.fsf@deeprootsystems.com> References: <1272891357-27400-1-git-send-email-ext-mika.1.westerberg@nokia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pw0-f46.google.com ([209.85.160.46]:52283 "EHLO mail-pw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933012Ab0ECQDW (ORCPT ); Mon, 3 May 2010 12:03:22 -0400 Received: by pwj9 with SMTP id 9so1267976pwj.19 for ; Mon, 03 May 2010 09:03:20 -0700 (PDT) In-Reply-To: <1272891357-27400-1-git-send-email-ext-mika.1.westerberg@nokia.com> (Mika Westerberg's message of "Mon\, 3 May 2010 15\:55\:57 +0300") Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Mika Westerberg Cc: tony@atomide.com, linux-omap@vger.kernel.org Mika Westerberg writes: > If we are softbooting another kernel using kexec, DMA controller state is not > known when we are performing omap_init_dma(). It is possible that some DMA > channels are already active. For example after kexec we get: > > <4>IRQ 0020 for non-allocated DMAchannel 5 > <4>IRQ 0020 for non-allocated DMAchannel 5 > <4>IRQ 0020 for non-allocated DMAchannel 5 > <4>IRQ 0020 for non-allocated DMAchannel 5 > <4>IRQ 0020 for non-allocated DMAchannel 5 > > To prevent any weird things happening, we perform soft reset for the controller > and disable all per channel interrupts. > > Signed-off-by: Mika Westerberg This is a good fix, but we get reset of DMA (and all other blocks) for free when switching to hwmod. Here's a good reason to convert DMA to hwmod. Kevin