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Subject: Re: [RFC 3/3] dmaengine: Support for requesting channels preferring
 DMA domain controller
To:     Vinod Koul <vkoul@kernel.org>
CC:     <robh+dt@kernel.org>, <dmaengine@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <dan.j.williams@intel.com>,
        <devicetree@vger.kernel.org>
References: <20190906141816.24095-1-peter.ujfalusi@ti.com>
 <20190906141816.24095-4-peter.ujfalusi@ti.com>
 <20190908121507.GN2672@vkoul-mobl>
From:   Peter Ujfalusi <peter.ujfalusi@ti.com>
Message-ID: <0bd4d678-31be-bead-7591-0452b6fed5f2@ti.com>
Date:   Mon, 9 Sep 2019 08:56:50 +0300
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On 08/09/2019 15.15, Vinod Koul wrote:
> On 06-09-19, 17:18, Peter Ujfalusi wrote:
>> In case the channel is not requested via the slave API, use the
>> of_find_dma_domain() to see if a system default DMA controller is
>> specified.
>>
>> Add new function which can be used by clients to request channels by mask
>> from their DMA domain controller if specified.
>>
>> Client drivers can take advantage of the domain support by moving from
>> dma_request_chan_by_mask() to dma_domain_request_chan_by_mask()
>>
>> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
>> ---
>>  drivers/dma/dmaengine.c   | 17 ++++++++++++-----
>>  include/linux/dmaengine.h |  9 ++++++---
>>  2 files changed, 18 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
>> index 6baddf7dcbfd..087450eed68c 100644
>> --- a/drivers/dma/dmaengine.c
>> +++ b/drivers/dma/dmaengine.c
>> @@ -640,6 +640,10 @@ struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
>>  	struct dma_device *device, *_d;
>>  	struct dma_chan *chan = NULL;
>>  
>> +	/* If np is not specified, get the default DMA domain controller */
>> +	if (!np)
>> +		np = of_find_dma_domain(NULL);
>> +
>>  	/* Find a channel */
>>  	mutex_lock(&dma_list_mutex);
>>  	list_for_each_entry_safe(device, _d, &dma_device_list, global_node) {
>> @@ -751,19 +755,22 @@ struct dma_chan *dma_request_slave_channel(struct device *dev,
>>  EXPORT_SYMBOL_GPL(dma_request_slave_channel);
>>  
>>  /**
>> - * dma_request_chan_by_mask - allocate a channel satisfying certain capabilities
>> - * @mask: capabilities that the channel must satisfy
>> + * dma_domain_request_chan_by_mask - allocate a channel by mask from DMA domain
>> + * @dev:	pointer to client device structure
>> + * @mask:	capabilities that the channel must satisfy
>>   *
>>   * Returns pointer to appropriate DMA channel on success or an error pointer.
>>   */
>> -struct dma_chan *dma_request_chan_by_mask(const dma_cap_mask_t *mask)
>> +struct dma_chan *dma_domain_request_chan_by_mask(struct device *dev,
>> +						 const dma_cap_mask_t *mask)
> 
> should we really use dma_request_chan_by_mask() why not create a new api
> dma_request_chan_by_domain() and use that, it falls back to
> dma_request_chan_by_mask() if it doesnt find a valid domain!

So:
struct dma_chan *dma_request_chan_by_domain(struct device *dev,
					    const dma_cap_mask_t *mask);

?

- Péter

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