From mboxrd@z Thu Jan  1 00:00:00 1970
From: vinod.koul@intel.com (Vinod Koul)
Date: Wed, 19 Aug 2015 22:23:49 +0530
Subject: [PATCHv4 2/6] dmaengine: mv_xor: add suspend/resume support
In-Reply-To: <20150729113405.2b337ae0@free-electrons.com>
References: <1436365699-6862-1-git-send-email-thomas.petazzoni@free-electrons.com>
 <1436365699-6862-3-git-send-email-thomas.petazzoni@free-electrons.com>
 <20150722051011.GQ23525@localhost>
 <20150729113405.2b337ae0@free-electrons.com>
Message-ID: <20150819165349.GJ13546@localhost>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Wed, Jul 29, 2015 at 11:34:05AM +0200, Thomas Petazzoni wrote:
> Vinod,
> 
> On Wed, 22 Jul 2015 10:40:11 +0530, Vinod Koul wrote:
> 
> > > +static int mv_xor_suspend(struct platform_device *pdev, pm_message_t state)
> > > +{
> > > +	struct mv_xor_device *xordev = platform_get_drvdata(pdev);
> > > +	int i;
> > > +
> > > +	for (i = 0; i < MV_XOR_MAX_CHANNELS; i++) {
> > > +		struct mv_xor_chan *mv_chan = xordev->channels[i];
> > > +
> > > +		if (!mv_chan)
> > > +			continue;
> > > +
> > > +		mv_chan->saved_config_reg =
> > > +			readl_relaxed(XOR_CONFIG(mv_chan));
> > > +		mv_chan->saved_int_mask_reg =
> > > +			readl_relaxed(XOR_INTR_MASK(mv_chan));
> > this sound fine, but I am missing the suspension of the channel. If a
> > transfer was active while suspend was invoked then how would this work?
> 
> There are indeed no provisions to handle this problem. Does the
> dmaengine framework provide any helpers to ease with this? I have
> quickly looked at other dmaengine drivers, and I haven't seen any of
> them taking care of this problem. Do you have a pointer to a driver
> handling this problem?

Sorry for delay...

Should this be solved at framework level? We should rather suspend the
channels, save the cfg and then restore that on resume.

-- 
~Vinod