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

Vinod Koul
2019-09-08T12:16:21Z

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!

--
~Vinod