Commit ab650ef6 authored Dec 08, 2020 by Peter Ujfalusi Committed by Vinod Koul Dec 11, 2020

dmaengine: Add support for per channel coherency handling



If the DMA device supports per channel coherency configuration (a channel
can be configured to have coherent or not coherent view) then a single
device (the DMA controller's device) can not be used for dma_api for all
channels as channels can have different coherency.

Introduce custom_dma_mapping flag for the dma_chan and a new helper to get
the device pointer to be used for dma_api for the given channel.

Client drivers should be updated to be able to support per channel
coherency by:

- dma_map_single(chan->device->dev, ptr, size, DMA_TO_DEVICE);
+ struct device *dma_dev = dmaengine_get_dma_device(chan);
+
+ dma_map_single(dma_dev, ptr, size, DMA_TO_DEVICE);

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Link: https://lore.kernel.org/r/20201208090440.31792-9-peter.ujfalusi@ti.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>

parent 4f910c03

include/linux/dmaengine.h

+12 −0

Original line number	Diff line number	Diff line
		@@ -357,11 +357,14 @@ struct dma_chan {
		* @chan: driver channel device
		* @device: sysfs device
		* @dev_id: parent dma_device dev_id
		* @chan_dma_dev: The channel is using custom/different dma-mapping
		* compared to the parent dma_device
		*/
		struct dma_chan_dev {
		struct dma_chan *chan;
		struct device device;
		int dev_id;
		bool chan_dma_dev;
		};

		/**
		@@ -1618,4 +1621,13 @@ dmaengine_get_direction_text(enum dma_transfer_direction dir)
		return "invalid";
		}
		}

		static inline struct device dmaengine_get_dma_device(struct dma_chan chan)
		{
		if (chan->dev->chan_dma_dev)
		return &chan->dev->device;

		return chan->device->dev;
		}

		#endif /* DMAENGINE_H */

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