linux-kernel - Re: [PATCH v4 6/7] DMA: sun6i: Add driver for the Allwinner A31 DMA controller

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Date:	Tue, 11 Mar 2014 10:22:52 +0000
From:	"Shevchenko, Andriy" <andriy.shevchenko@...el.com>
To:	Maxime Ripard <maxime.ripard@...e-electrons.com>
CC:	Emilio Lopez <emilio@...pez.com.ar>,
	"Williams, Dan J" <dan.j.williams@...el.com>,
	"Koul, Vinod" <vinod.koul@...el.com>,
	"Mike Turquette" <mturquette@...aro.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"dmaengine@...r.kernel.org" <dmaengine@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-sunxi@...glegroups.com" <linux-sunxi@...glegroups.com>,
	"kevin.z.m.zh@...il.com" <kevin.z.m.zh@...il.com>,
	"sunny@...winnertech.com" <sunny@...winnertech.com>,
	"shuge@...winnertech.com" <shuge@...winnertech.com>,
	"zhuzhenhua@...winnertech.com" <zhuzhenhua@...winnertech.com>
Subject: Re: [PATCH v4 6/7] DMA: sun6i: Add driver for the Allwinner A31 DMA
 controller

On Tue, 2014-03-11 at 11:08 +0100, Maxime Ripard wrote:

[]

> > > +	spin_lock_irq(&sdev->lock);
> > > +	for (pchan_idx = 0; pchan_idx < NR_MAX_CHANNELS; pchan_idx++) {
> > > +		pchan = &sdev->pchans[pchan_idx];
> > > +
> > > +		if (pchan->vchan == NULL && !list_empty(&sdev->pending)) {
> > 
> > !pchan->vchan && ...
> 
> Ok.
> 
> > And you may decrease indentation level here if you use negative
> > condition.
> 
> Hmmm, I'm not following you here. What do you mean?

for () {
...
if (!(your current condition))
 continue;
... (do something else with decreased indentation level)
}

> > > +			vchan = list_first_entry(&sdev->pending,
> > > +						 struct sun6i_vchan, node);
> > > +
> > > +			/* Remove from pending channels */
> > > +			list_del_init(&vchan->node);
> > > +			pchan_alloc |= BIT(pchan_idx);
> > > +
> > > +			/* Mark this channel allocated */
> > > +			pchan->vchan = vchan;
> > > +			vchan->phy = pchan;
> > > +			dev_dbg(sdev->slave.dev, "pchan %u: alloc vchan %p\n",
> > > +				pchan->idx, &vchan->vc);
> > > +		}
> > > +	}
> > > +	spin_unlock_irq(&sdev->lock);
> > > +
> > > +	for (pchan_idx = 0; pchan_idx < NR_MAX_CHANNELS; pchan_idx++) {
> > > +		if (pchan_alloc & BIT(pchan_idx)) {
> > 
> > Ditto.

Same here.

[]

> > > +#ifdef DEBUG
> > > +	dev_dbg(chan2dev(chan), "First: %pad\n", &txd->p_lli);
> > 
> > dev_dbg is aware of DEBUG. So, please, remove that #ifdef at all.
> 
> Yep, but the line just below isn't.
> 
> The ifdef here is not really to prevent the call to dev_dbg, but rather...
> 
> > > +	for (prev = txd->v_lli; prev != NULL; prev = prev->v_lli_next)
> 
> ... this.

It doesn't matter since implementation of sun6i_dma_dump_lli is (and
actually should be) aware of DEBUG already, because it's dev_dbg based.

> > 
> > You may remove '!= NULL' part.
> 
> Ok.
> 
> > > +		sun6i_dma_dump_lli(vchan, prev);
> > > +#endif




-- 
Andy Shevchenko <andriy.shevchenko@...el.com>
Intel Finland Oy
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