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

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Date:	Mon, 29 Aug 2011 20:51:25 +0530
From:	Vinod Koul <vinod.koul@...ux.intel.com>
To:	Guennadi Liakhovetski <g.liakhovetski@....de>
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 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?

-- 
~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);



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