[PATCH v3 10/59] dmaengine: Create a generic dma_slave_caps callback

Maxime Ripard
2014-10-22T15:45:22Z

dma_slave_caps is very important to the generic layers that might interact with
dmaengine, such as ASoC. Unfortunately, it has been added as yet another
dma_device callback, and most of the existing drivers haven't implemented it,
reducing its reliability.

Introduce a generic behaviour and a flag to trigger it. In case this flag
hasn't been set, fall back to the old mechanism.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
---
include/linux/dmaengine.h | 25 +++++++++++++++++++++----
1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index b0efc805937a..6b74d9d8977e 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -642,6 +642,8 @@ struct dma_device {
int dev_id;
struct device *dev;

+ bool generic_slave_caps;
+
int (*device_alloc_chan_resources)(struct dma_chan *chan);
void (*device_free_chan_resources)(struct dma_chan *chan);

@@ -783,17 +785,32 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_dma_sg(

static inline int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps)
{
+ struct dma_device *device;
+
if (!chan || !caps)
return -EINVAL;

+ device = chan->device;
+
/* check if the channel supports slave transactions */
- if (!test_bit(DMA_SLAVE, chan->device->cap_mask.bits))
+ if (!test_bit(DMA_SLAVE, device->cap_mask.bits))
+ return -ENXIO;
+
+ if (device->device_slave_caps)
+ return device->device_slave_caps(chan, caps);
+
+ /*
+ * Check whether it reports it uses the generic slave
+ * capabilities, if not, that means it doesn't support any
+ * kind of slave capabilities reporting.
+ */
+ if (device->generic_slave_caps)
return -ENXIO;

- if (chan->device->device_slave_caps)
- return chan->device->device_slave_caps(chan, caps);
+ caps->cmd_pause = !!device->device_pause;
+ caps->cmd_terminate = !!device->device_terminate_all;

- return -ENXIO;
+ return 0;
}

static inline int dmaengine_terminate_all(struct dma_chan *chan)
--
2.1.1