linux-kernel - RE: [PATCH v2] dmaengine: add CSR SiRFprimaII DMAC driver

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Date:	Mon, 19 Sep 2011 09:56:10 +0000
From:	Barry Song <Barry.Song@....com>
To:	Vinod Koul <vinod.koul@...el.com>
CC:	"21cnbao@...il.com" <21cnbao@...il.com>,
	Arnd Bergmann <arnd@...db.de>,
	Jassi Brar <jaswinder.singh@...aro.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	DL-SHA-WorkGroupLinux <Workgroup.Linux@....com>,
	Rongjun Ying <Rongjun.Ying@....com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: RE: [PATCH v2] dmaengine: add CSR SiRFprimaII DMAC driver



> -----Original Message-----
> From: Vinod Koul [mailto:vinod.koul@...el.com]
> Sent: 2011年9月19日 17:41
> To: Barry Song
> Cc: 21cnbao@...il.com; Arnd Bergmann; Jassi Brar; Linus Walleij;
> linux-kernel@...r.kernel.org; DL-SHA-WorkGroupLinux; Rongjun Ying;
> linux-arm-kernel@...ts.infradead.org
> Subject: RE: [PATCH v2] dmaengine: add CSR SiRFprimaII DMAC driver
> 
> On Mon, 2011-09-19 at 09:23 +0000, Barry Song wrote:
> > Hi Vinod,
> > Thanks!
> >
> > > -----Original Message-----
> > > From: Vinod Koul [mailto:vinod.koul@...el.com]
> > > Sent: 2011年9月19日 17:00
> > > To: Barry Song
> > > Cc: Arnd Bergmann; Jassi Brar; Linus Walleij; linux-kernel@...r.kernel.org;
> > > DL-SHA-WorkGroupLinux; Rongjun Ying;
> linux-arm-kernel@...ts.infradead.org
> > > Subject: Re: [PATCH v2] dmaengine: add CSR SiRFprimaII DMAC driver
> > >
> > > On Fri, 2011-09-16 at 02:56 -0700, Barry Song wrote:
> > > > From: Rongjun Ying <rongjun.ying@....com>
> > > >
> > > > Cc: Jassi Brar <jaswinder.singh@...aro.org>
> > > > Cc: Arnd Bergmann <arnd@...db.de>
> > > > Cc: Linus Walleij <linus.walleij@...aro.org>
> > > > Signed-off-by: Rongjun Ying <rongjun.ying@....com>
> > > > Signed-off-by: Barry Song <Baohua.Song@....com>
> > > > ---
> > > >  -v2:
> > > >  use generic xfer API from jassi;
> > > >  delete sirf self-defined slave config;
> > > >  fix feedback from vinod;
> > > >  fix filter function: we have two dmac, clients drivers think the chan id as
> > > 0~31;
> > > >  rename regs to base;
> > > >  delete redundant chan_id initialization in probe since dmaengine core
> will
> > > >  re-write it, refer to my patch too:
> > > >  [PATCH] dmaengine: delete redundant chan_id and chancnt initialization
> in
> > > dma drivers
> > > >  http://www.spinics.net/lists/kernel/msg1237455.html
> > > >
> > > >  this patch doesn't provide a common way for filter and doesn't use the
> > > jassi's v2 patch.
> > > > +
> > > > +static int sirfsoc_dma_slave_config(struct sirfsoc_dma_chan *schan,
> > > > +	struct dma_slave_config *config)
> > > > +{
> > > > +	u32 addr, direction;
> > > > +	unsigned long flags;
> > > > +
> > > > +	switch (config->direction) {
> > > > +	case DMA_FROM_DEVICE:
> > > > +		direction = 0;
> > > > +		addr = config->dst_addr;
> > > > +		break;
> > > > +
> > > > +	case DMA_TO_DEVICE:
> > > > +		direction = 1;
> > > > +		addr = config->src_addr;
> > > > +		break;
> > > > +
> > > > +	default:
> > > > +		return -EINVAL;
> > > > +	}
> > > > +
> > > > +	if ((config->src_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES) ||
> > > > +		(config->dst_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES))
> > > > +		return -EINVAL;
> > > > +
> > > > +	spin_lock_irqsave(&schan->lock, flags);
> > > > +	schan->addr = addr;
> > > > +	schan->direction = direction;
> > > > +	schan->mode = (config->src_maxburst == 4 ? 1 : 0);
> > > > +	spin_unlock_irqrestore(&schan->lock, flags);
> > > Not sure why you support this, there seem to be no DMA_SLAVE support in
> > > this version ate least
> >
> > Not. I support dma_slave. But I have no prep_slave_sg function since I can
> use the gen xfer to replace it.
> Yes thats okay...
> 
> Then I have questions on genxfer function...
> where are you copying either src or dstn_start address, you seem to
> completely ignore them?

Since I only support memory->device or device ->memory, and channel number is fixed to every device. Then I actually don't care device address at all. Either src or dst is fixed to the device's address.

> 
> Do you support only slave transfers or M2M as well for this driver?
> If only slave you might want to check if dma_config_slave is set for
> this channel or not.

I support only slave transfer. Actually I have dma_config_slave. do you mean I need to check whether slave config cmd is really called before executing dma?

> 
> --
> ~Vinod

-barry



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