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 10:05:06 -0700 Message-ID: <87fx285325.fsf@deeprootsystems.com> References: <1272891357-27400-1-git-send-email-ext-mika.1.westerberg@nokia.com> <87zl0h6khl.fsf@deeprootsystems.com> <20100503163600.GQ29604@atomide.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pv0-f174.google.com ([74.125.83.174]:36389 "EHLO mail-pv0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754363Ab0ECRFJ (ORCPT ); Mon, 3 May 2010 13:05:09 -0400 Received: by pva4 with SMTP id 4so590151pva.19 for ; Mon, 03 May 2010 10:05:08 -0700 (PDT) In-Reply-To: <20100503163600.GQ29604@atomide.com> (Tony Lindgren's message of "Mon\, 3 May 2010 09\:36\:01 -0700") Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Tony Lindgren Cc: Mika Westerberg , linux-omap@vger.kernel.org Tony Lindgren writes: > * Kevin Hilman [100503 08:58]: >> 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. > > Hmm, do we have existing DMA hwmod patches somewhere that work on all omaps? No, that's my point. Rather than implement reset here (then remove it with DMA hwmods) I'd rather just see a DMA hwmods added, and then we get reset for free. Kevin