linux-kernel - Re: [PATCH 1/2] dmaengine: ipu-idmac: add support for the DMA

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Date:	Mon, 29 Aug 2011 19:50:13 +0200 (CEST)
From:	Guennadi Liakhovetski <g.liakhovetski@....de>
To:	Vinod Koul <vinod.koul@...ux.intel.com>
cc:	Linux Media Mailing List <linux-media@...r.kernel.org>,
	Sakari Ailus <sakari.ailus@...well.research.nokia.com>,
	Pawel Osciak <pawel@...iak.com>, linux-kernel@...r.kernel.org,
	Mauro Carvalho Chehab <mchehab@...radead.org>,
	Hans Verkuil <hverkuil@...all.nl>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Sascha Hauer <kernel@...gutronix.de>,
	Dan Williams <dan.j.williams@...el.com>,
	linux-arm-kernel@...ts.infradead.org,
	Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [PATCH 1/2] dmaengine: ipu-idmac: add support for the DMA_PAUSE
 control

On Mon, 29 Aug 2011, Vinod Koul wrote:

> On Thu, 2011-08-25 at 18:45 +0200, Guennadi Liakhovetski wrote:
> > To support multi-size buffers in the mx3_camera V4L2 driver we have to be
> > able to stop DMA on a channel without releasing descriptors and completely
> > halting the hardware. Use the DMA_PAUSE control to implement this mode.
> > 
> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@....de>
> Acked-by Vinod Koul <vinod.koul@...ux.intel.com>
> 
> Do you want this to go thru slave-dma or media tree?

With your above ack I can pull it together with the final form of patch 
2/2, when it's ready, via media tree. 

Thanks
Guennadi

> 
> -- 
> ~Vinod
> > ---
> >  drivers/dma/ipu/ipu_idmac.c |   65 +++++++++++++++++++++++++++---------------
> >  1 files changed, 42 insertions(+), 23 deletions(-)
> > 
> > diff --git a/drivers/dma/ipu/ipu_idmac.c b/drivers/dma/ipu/ipu_idmac.c
> > index c1a125e..42cdf1c 100644
> > --- a/drivers/dma/ipu/ipu_idmac.c
> > +++ b/drivers/dma/ipu/ipu_idmac.c
> > @@ -1306,6 +1306,7 @@ static irqreturn_t idmac_interrupt(int irq, void *dev_id)
> >  	    ipu_submit_buffer(ichan, descnew, sgnew, ichan->active_buffer) < 0) {
> >  		callback = descnew->txd.callback;
> >  		callback_param = descnew->txd.callback_param;
> > +		list_del_init(&descnew->list);
> >  		spin_unlock(&ichan->lock);
> >  		if (callback)
> >  			callback(callback_param);
> > @@ -1427,39 +1428,58 @@ static int __idmac_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
> >  {
> >  	struct idmac_channel *ichan = to_idmac_chan(chan);
> >  	struct idmac *idmac = to_idmac(chan->device);
> > +	struct ipu *ipu = to_ipu(idmac);
> > +	struct list_head *list, *tmp;
> >  	unsigned long flags;
> >  	int i;
> >  
> > -	/* Only supports DMA_TERMINATE_ALL */
> > -	if (cmd != DMA_TERMINATE_ALL)
> > -		return -ENXIO;
> > +	switch (cmd) {
> > +	case DMA_PAUSE:
> > +		spin_lock_irqsave(&ipu->lock, flags);
> > +		ipu_ic_disable_task(ipu, chan->chan_id);
> >  
> > -	ipu_disable_channel(idmac, ichan,
> > -			    ichan->status >= IPU_CHANNEL_ENABLED);
> > +		/* Return all descriptors into "prepared" state */
> > +		list_for_each_safe(list, tmp, &ichan->queue)
> > +			list_del_init(list);
> >  
> > -	tasklet_disable(&to_ipu(idmac)->tasklet);
> > +		ichan->sg[0] = NULL;
> > +		ichan->sg[1] = NULL;
> >  
> > -	/* ichan->queue is modified in ISR, have to spinlock */
> > -	spin_lock_irqsave(&ichan->lock, flags);
> > -	list_splice_init(&ichan->queue, &ichan->free_list);
> > +		spin_unlock_irqrestore(&ipu->lock, flags);
> >  
> > -	if (ichan->desc)
> > -		for (i = 0; i < ichan->n_tx_desc; i++) {
> > -			struct idmac_tx_desc *desc = ichan->desc + i;
> > -			if (list_empty(&desc->list))
> > -				/* Descriptor was prepared, but not submitted */
> > -				list_add(&desc->list, &ichan->free_list);
> > +		ichan->status = IPU_CHANNEL_INITIALIZED;
> > +		break;
> > +	case DMA_TERMINATE_ALL:
> > +		ipu_disable_channel(idmac, ichan,
> > +				    ichan->status >= IPU_CHANNEL_ENABLED);
> >  
> > -			async_tx_clear_ack(&desc->txd);
> > -		}
> > +		tasklet_disable(&ipu->tasklet);
> >  
> > -	ichan->sg[0] = NULL;
> > -	ichan->sg[1] = NULL;
> > -	spin_unlock_irqrestore(&ichan->lock, flags);
> > +		/* ichan->queue is modified in ISR, have to spinlock */
> > +		spin_lock_irqsave(&ichan->lock, flags);
> > +		list_splice_init(&ichan->queue, &ichan->free_list);
> >  
> > -	tasklet_enable(&to_ipu(idmac)->tasklet);
> > +		if (ichan->desc)
> > +			for (i = 0; i < ichan->n_tx_desc; i++) {
> > +				struct idmac_tx_desc *desc = ichan->desc + i;
> > +				if (list_empty(&desc->list))
> > +					/* Descriptor was prepared, but not submitted */
> > +					list_add(&desc->list, &ichan->free_list);
> >  
> > -	ichan->status = IPU_CHANNEL_INITIALIZED;
> > +				async_tx_clear_ack(&desc->txd);
> > +			}
> > +
> > +		ichan->sg[0] = NULL;
> > +		ichan->sg[1] = NULL;
> > +		spin_unlock_irqrestore(&ichan->lock, flags);
> > +
> > +		tasklet_enable(&ipu->tasklet);
> > +
> > +		ichan->status = IPU_CHANNEL_INITIALIZED;
> > +		break;
> > +	default:
> > +		return -ENOSYS;
> > +	}
> >  
> >  	return 0;
> >  }
> > @@ -1662,7 +1682,6 @@ static void __exit ipu_idmac_exit(struct ipu *ipu)
> >  		struct idmac_channel *ichan = ipu->channel + i;
> >  
> >  		idmac_control(&ichan->dma_chan, DMA_TERMINATE_ALL, 0);
> > -		idmac_prep_slave_sg(&ichan->dma_chan, NULL, 0, DMA_NONE, 0);
> >  	}
> >  
> >  	dma_async_device_unregister(&idmac->dma);
> 
> 
> 

---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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