linux-kernel - Re: [PATCH v3 1/2] dma: pl330: improve pl330_tx

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Date:	Wed, 11 Feb 2015 11:50:22 +0100
From:	Robert Baldyga <r.baldyga@...sung.com>
To:	Vinod Koul <vinod.koul@...el.com>
Cc:	dan.j.williams@...el.com, lars@...afoo.de,
	dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
	m.szyprowski@...sung.com, k.kozlowski@...sung.com,
	kyungmin.park@...sung.com, l.czerwinski@...sung.com,
	padma.kvr@...il.com
Subject: Re: [PATCH v3 1/2] dma: pl330: improve pl330_tx_status() function

On 02/11/2015 01:23 AM, Vinod Koul wrote:
> 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@...sung.com>
>> Signed-off-by: Robert Baldyga <r.baldyga@...sung.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.
> 

Ok, I will send v4.

Thanks,
Robert Baldyga
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