Re: [PATCH v3 1/2] dma: pl330: improve pl330_tx_status() function

[Vinod Koul <vinod.koul@intel.com>]

On Wed, Dec 10, 2014 at 11:55:17AM +0100, Robert Baldyga wrote:
> This patch adds possibility to read residue of DMA transfer. It's useful
> when we want to know how many bytes have been transferred before we
> terminate channel. It can take place, for example, on timeout interrupt.
> 
> Signed-off-by: Lukasz Czerwinski <l.czerwinski@samsung.com>
> Signed-off-by: Robert Baldyga <r.baldyga@samsung.com>
> ---
>  drivers/dma/pl330.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 66 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
> index bdf40b5..2f4d561 100644
> --- a/drivers/dma/pl330.c
> +++ b/drivers/dma/pl330.c
> @@ -504,6 +504,9 @@ struct dma_pl330_desc {
>  
>  	enum desc_status status;
>  
> +	int bytes_requested;
> +	bool last;
> +
>  	/* The channel which currently holds this desc */
>  	struct dma_pl330_chan *pchan;
>  
> @@ -2182,11 +2185,68 @@ static void pl330_free_chan_resources(struct dma_chan *chan)
>  	pm_runtime_put_autosuspend(pch->dmac->ddma.dev);
>  }
>  
> +int pl330_get_current_xferred_count(struct dma_pl330_chan *pch,
> +		struct dma_pl330_desc *desc)
> +{
> +	struct pl330_thread *thrd = pch->thread;
> +	struct pl330_dmac *pl330 = pch->dmac;
> +	void __iomem *regs = thrd->dmac->base;
> +	u32 val, addr;
> +
> +	pm_runtime_get_sync(pl330->ddma.dev);
> +	val = addr = 0;
> +	if (desc->rqcfg.src_inc) {
> +		val = readl(regs + SA(thrd->id));
> +		addr = desc->px.src_addr;
> +	} else {
> +		val = readl(regs + DA(thrd->id));
> +		addr = desc->px.dst_addr;
> +	}
> +	pm_runtime_mark_last_busy(pch->dmac->ddma.dev);
> +	pm_runtime_put_autosuspend(pl330->ddma.dev);
> +	return val - addr;
> +}
> +
>  static enum dma_status
>  pl330_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
>  		 struct dma_tx_state *txstate)
>  {
> -	return dma_cookie_status(chan, cookie, txstate);
> +	enum dma_status ret;
> +	unsigned long flags;
> +	struct dma_pl330_desc *desc, *running = NULL;
> +	struct dma_pl330_chan *pch = to_pchan(chan);
> +	unsigned int transferred, residual = 0;
> +
> +	spin_lock_irqsave(&pch->lock, flags);
You want to check the dma_cookie_status here first and then based on status
go into residue calcaultion, that too only when the txstate is NON null.

-- 
~Vinod

> +
> +	if (pch->thread->req_running != -1)
> +		running = pch->thread->req[pch->thread->req_running].desc;
> +
> +	/* Check in pending list */
> +	list_for_each_entry(desc, &pch->work_list, node) {
> +		if (desc->status == DONE)
> +			transferred = desc->bytes_requested;
> +		else if (running && desc == running)
> +			transferred =
> +				pl330_get_current_xferred_count(pch, desc);
> +		else
> +			transferred = 0;
> +		residual += desc->bytes_requested - transferred;
> +		if (desc->txd.cookie == cookie) {
> +			dma_set_residue(txstate, residual);
> +			ret = desc->status;
> +			spin_unlock_irqrestore(&pch->lock, flags);
> +			return ret;
> +		}
> +		if (desc->last)
> +			residual = 0;
> +	}
> +	spin_unlock_irqrestore(&pch->lock, flags);
> +
> +	ret = dma_cookie_status(chan, cookie, txstate);
> +	dma_set_residue(txstate, 0);
> +
> +	return ret;
>  }
>  
>  static void pl330_issue_pending(struct dma_chan *chan)
> @@ -2231,12 +2291,14 @@ static dma_cookie_t pl330_tx_submit(struct dma_async_tx_descriptor *tx)
>  			desc->txd.callback = last->txd.callback;
>  			desc->txd.callback_param = last->txd.callback_param;
>  		}
> +		last->last = false;
>  
>  		dma_cookie_assign(&desc->txd);
>  
>  		list_move_tail(&desc->node, &pch->submitted_list);
>  	}
>  
> +	last->last = true;
>  	cookie = dma_cookie_assign(&last->txd);
>  	list_add_tail(&last->node, &pch->submitted_list);
>  	spin_unlock_irqrestore(&pch->lock, flags);
> @@ -2459,6 +2521,7 @@ static struct dma_async_tx_descriptor *pl330_prep_dma_cyclic(
>  		desc->rqtype = direction;
>  		desc->rqcfg.brst_size = pch->burst_sz;
>  		desc->rqcfg.brst_len = 1;
> +		desc->bytes_requested = period_len;
>  		fill_px(&desc->px, dst, src, period_len);
>  
>  		if (!first)
> @@ -2601,6 +2664,7 @@ pl330_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
>  		desc->rqcfg.brst_size = pch->burst_sz;
>  		desc->rqcfg.brst_len = 1;
>  		desc->rqtype = direction;
> +		desc->bytes_requested = sg_dma_len(sg);
>  	}
>  
>  	/* Return the last desc in the chain */
> @@ -2631,7 +2695,7 @@ static int pl330_dma_device_slave_caps(struct dma_chan *dchan,
>  	caps->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
>  	caps->cmd_pause = false;
>  	caps->cmd_terminate = true;
> -	caps->residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;
> +	caps->residue_granularity = DMA_RESIDUE_GRANULARITY_SEGMENT;
>  
>  	return 0;
>  }
> -- 
> 1.9.1
> 

--