linux-kernel - Re: [PATCH v7] DMA: sun6i: Add driver for the Allwinner A31 DMA controller

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Date:	Wed, 21 May 2014 11:01:05 +0530
From:	Vinod Koul <vinod.koul@...el.com>
To:	Maxime Ripard <maxime.ripard@...e-electrons.com>
Cc:	Dan Williams <dan.j.williams@...el.com>,
	linux-arm-kernel@...ts.infradead.org, dmaengine@...r.kernel.org,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	linux-sunxi@...glegroups.com, kevin.z.m.zh@...il.com,
	sunny@...winnertech.com, shuge@...winnertech.com,
	zhuzhenhua@...winnertech.com, andriy.shevchenko@...el.com,
	Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH v7] DMA: sun6i: Add driver for the Allwinner A31 DMA
 controller

On Tue, May 13, 2014 at 03:42:58PM +0200, Maxime Ripard wrote:
> Hi Vinod,
> 
> On Wed, Apr 30, 2014 at 12:34:08PM +0530, Vinod Koul wrote:
> > > +
> > > +static int sun6i_dma_terminate_all(struct sun6i_vchan *vchan)
> > > +{
> > > +	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(vchan->vc.chan.device);
> > > +	struct sun6i_pchan *pchan = vchan->phy;
> > > +	unsigned long flags;
> > > +	LIST_HEAD(head);
> > > +
> > > +	spin_lock(&sdev->lock);
> > > +	list_del_init(&vchan->node);
> > > +	spin_unlock(&sdev->lock);
> > > +
> > > +	spin_lock_irqsave(&vchan->vc.lock, flags);
> > > +
> > > +	vchan_get_all_descriptors(&vchan->vc, &head);
> > > +
> > > +	if (pchan) {
> > > +		writel(DMA_CHAN_ENABLE_STOP, pchan->base + DMA_CHAN_ENABLE);
> > > +		writel(DMA_CHAN_PAUSE_RESUME, pchan->base + DMA_CHAN_PAUSE);
> > > +
> > > +		vchan->phy = NULL;
> > > +		pchan->vchan = NULL;
> > > +		pchan->desc = NULL;
> > > +		pchan->done = NULL;
> > > +	}
> > > +
> > > +	spin_unlock_irqrestore(&vchan->vc.lock, flags);
> > > +
> > > +	vchan_dma_desc_free_list(&vchan->vc, &head);
> > 
> > shouldn't you kill the tasklet as well here?
> 
> Just to be clear, which tasklet? vchan's or the driver's?
You need to take care of both. But I suspect if we ensure irq is not triggered
and any pending ones are completed you can simply kill both of the tasklets
happily. See the fixes merged in dmaengine last cycle (hint: patchlog shows what
we need to do)

Btw just noticed, you *should* use dmaengine: as the subsytem name on the patch
series...

-- 
~Vinod

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