On 08/30/2017 11:18 AM, Robin Murphy wrote:
> On 25/08/17 21:59, Dave Jiang wrote:
>> Adding a dmaengine transaction operation that allows copy to/from a
>> scatterlist and a flat buffer.
>
> Apologies if I'm late to the party, but doesn't DMA_SG already cover
> this use-case? As far as I can see, all this does is save the caller
> from setting up a single-entry scatterlist to describe the buffer - even
> if such a simplified interface is justified it seems like something that
> could be implemented as a wrapper around dmaengine_prep_dma_sg() rather
> than the providers having to implement a whole extra callback.
>
DMA_SG is queued to be removed in 4.14. There is no in kernel consumer
for the code.
> Robin.
>
>>
>> Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
>> ---
>> Documentation/dmaengine/provider.txt | 3 +++
>> drivers/dma/dmaengine.c | 2 ++
>> include/linux/dmaengine.h | 19 +++++++++++++++++++
>> 3 files changed, 24 insertions(+)
>>
>> diff --git a/Documentation/dmaengine/provider.txt b/Documentation/dmaengine/provider.txt
>> index a75f52f..6241e36 100644
>> --- a/Documentation/dmaengine/provider.txt
>> +++ b/Documentation/dmaengine/provider.txt
>> @@ -181,6 +181,9 @@ Currently, the types available are:
>> - Used by the client drivers to register a callback that will be
>> called on a regular basis through the DMA controller interrupt
>>
>> + * DMA_MEMCPY_SG
>> + - The device supports scatterlist to/from memory.
>> +
>> * DMA_PRIVATE
>> - The devices only supports slave transfers, and as such isn't
>> available for async transfers.
>> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
>> index 428b141..4d2c4e1 100644
>> --- a/drivers/dma/dmaengine.c
>> +++ b/drivers/dma/dmaengine.c
>> @@ -937,6 +937,8 @@ int dma_async_device_register(struct dma_device *device)
>> !device->device_prep_dma_memset);
>> BUG_ON(dma_has_cap(DMA_INTERRUPT, device->cap_mask) &&
>> !device->device_prep_dma_interrupt);
>> + BUG_ON(dma_has_cap(DMA_MEMCPY_SG, device->cap_mask) &&
>> + !device->device_prep_dma_memcpy_sg);
>> BUG_ON(dma_has_cap(DMA_CYCLIC, device->cap_mask) &&
>> !device->device_prep_dma_cyclic);
>> BUG_ON(dma_has_cap(DMA_INTERLEAVE, device->cap_mask) &&
>> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
>> index 64fbd38..0c91411 100644
>> --- a/include/linux/dmaengine.h
>> +++ b/include/linux/dmaengine.h
>> @@ -67,6 +67,7 @@ enum dma_transaction_type {
>> DMA_PQ_VAL,
>> DMA_MEMSET,
>> DMA_MEMSET_SG,
>> + DMA_MEMCPY_SG,
>> DMA_INTERRUPT,
>> DMA_PRIVATE,
>> DMA_ASYNC_TX,
>> @@ -692,6 +693,7 @@ struct dma_filter {
>> * @device_prep_dma_pq_val: prepares a pqzero_sum operation
>> * @device_prep_dma_memset: prepares a memset operation
>> * @device_prep_dma_memset_sg: prepares a memset operation over a scatter list
>> + * @device_prep_dma_memcpy_sg: prepares memcpy between scatterlist and buffer
>> * @device_prep_dma_interrupt: prepares an end of chain interrupt operation
>> * @device_prep_slave_sg: prepares a slave dma operation
>> * @device_prep_dma_cyclic: prepare a cyclic dma operation suitable for audio.
>> @@ -768,6 +770,10 @@ struct dma_device {
>> struct dma_async_tx_descriptor *(*device_prep_dma_memset_sg)(
>> struct dma_chan *chan, struct scatterlist *sg,
>> unsigned int nents, int value, unsigned long flags);
>> + struct dma_async_tx_descriptor *(*device_prep_dma_memcpy_sg)(
>> + struct dma_chan *chan,
>> + struct scatterlist *sg, unsigned int sg_nents,
>> + dma_addr_t buf, bool to_sg, unsigned long flags);
>> struct dma_async_tx_descriptor *(*device_prep_dma_interrupt)(
>> struct dma_chan *chan, unsigned long flags);
>>
>> @@ -899,6 +905,19 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_dma_memcpy(
>> len, flags);
>> }
>>
>> +static inline struct dma_async_tx_descriptor *dmaengine_prep_dma_memcpy_sg(
>> + struct dma_chan *chan, struct scatterlist *sg,
>> + unsigned int sg_nents, dma_addr_t buf, bool to_sg,
>> + unsigned long flags)
>> +{
>> + if (!chan || !chan->device ||
>> + !chan->device->device_prep_dma_memcpy_sg)
>> + return NULL;
>> +
>> + return chan->device->device_prep_dma_memcpy_sg(chan, sg, sg_nents,
>> + buf, to_sg, flags);
>> +}
>> +
>> /**
>> * dmaengine_terminate_all() - Terminate all active DMA transfers
>> * @chan: The channel for which to terminate the transfers
>>
--
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