linux-kernel - Re: [RFC 3/3] dmaengine: Support for requesting channels preferring DMA domain controller

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Message-ID: <a409fb40-c8d7-2f0d-20fb-1786b2cbe6fd@ti.com>
Date:   Sun, 8 Sep 2019 10:46:05 +0300
From:   Peter Ujfalusi <peter.ujfalusi@...com>
To:     <vkoul@...nel.org>, <robh+dt@...nel.org>
CC:     <dmaengine@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <dan.j.williams@...el.com>, <devicetree@...r.kernel.org>
Subject: Re: [RFC 3/3] dmaengine: Support for requesting channels preferring
 DMA domain controller



On 06/09/2019 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@...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)
>  {
>  	struct dma_chan *chan;
>  
>  	if (!mask)
>  		return ERR_PTR(-ENODEV);
>  
> -	chan = __dma_request_channel(mask, NULL, NULL, NULL);

if (dev)
> +	chan = __dma_request_channel(mask, NULL, NULL,
> +				     of_find_dma_domain(dev->of_node));else
	chan = __dma_request_channel(mask, NULL, NULL, NULL);

>  	if (!chan) {
>  		mutex_lock(&dma_list_mutex);
>  		if (list_empty(&dma_device_list))
> @@ -775,7 +782,7 @@ struct dma_chan *dma_request_chan_by_mask(const dma_cap_mask_t *mask)
>  
>  	return chan;
>  }
> -EXPORT_SYMBOL_GPL(dma_request_chan_by_mask);
> +EXPORT_SYMBOL_GPL(dma_domain_request_chan_by_mask);
>  
>  void dma_release_channel(struct dma_chan *chan)
>  {
> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> index 3b2e8e302f6c..9f94df81e83f 100644
> --- a/include/linux/dmaengine.h
> +++ b/include/linux/dmaengine.h
> @@ -1438,7 +1438,8 @@ struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
>  struct dma_chan *dma_request_slave_channel(struct device *dev, const char *name);
>  
>  struct dma_chan *dma_request_chan(struct device *dev, const char *name);
> -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);
>  
>  void dma_release_channel(struct dma_chan *chan);
>  int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps);
> @@ -1475,8 +1476,8 @@ static inline struct dma_chan *dma_request_chan(struct device *dev,
>  {
>  	return ERR_PTR(-ENODEV);
>  }
> -static inline struct dma_chan *dma_request_chan_by_mask(
> -						const dma_cap_mask_t *mask)
> +static inline struct dma_chan *dma_domain_request_chan_by_mask(struct device *dev,
> +			const dma_cap_mask_t *mask)
>  {
>  	return ERR_PTR(-ENODEV);
>  }
> @@ -1537,6 +1538,8 @@ struct dma_chan *dma_get_any_slave_channel(struct dma_device *device);
>  	__dma_request_channel(&(mask), x, y, NULL)
>  #define dma_request_slave_channel_compat(mask, x, y, dev, name) \
>  	__dma_request_slave_channel_compat(&(mask), x, y, dev, name)
> +#define dma_request_chan_by_mask(mask) \
> +	dma_domain_request_chan_by_mask(NULL, mask)
>  
>  static inline struct dma_chan
>  *__dma_request_slave_channel_compat(const dma_cap_mask_t *mask,
> 

- Péter

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