Re: [PATCH v4 05/15] dmaengine: Add support for reporting DMA cached data amount

Vinod Koul
2019-11-11T04:40:09Z

On 01-11-19, 10:41, Peter Ujfalusi wrote:
> A DMA hardware can have big cache or FIFO and the amount of data sitting in
> the DMA fabric can be an interest for the clients.
>
> For example in audio we want to know the delay in the data flow and in case
> the DMA have significantly large FIFO/cache, it can affect the latenc/delay
>
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
> Reviewed-by: Tero Kristo <t-kristo@ti.com>
> ---
> drivers/dma/dmaengine.h | 8 ++++++++
> include/linux/dmaengine.h | 2 ++
> 2 files changed, 10 insertions(+)
>
> diff --git a/drivers/dma/dmaengine.h b/drivers/dma/dmaengine.h
> index 501c0b063f85..b0b97475707a 100644
> --- a/drivers/dma/dmaengine.h
> +++ b/drivers/dma/dmaengine.h
> @@ -77,6 +77,7 @@ static inline enum dma_status dma_cookie_status(struct dma_chan *chan,
> state->last = complete;
> state->used = used;
> state->residue = 0;
> + state->in_flight_bytes = 0;
> }
> return dma_async_is_complete(cookie, complete, used);
> }
> @@ -87,6 +88,13 @@ static inline void dma_set_residue(struct dma_tx_state *state, u32 residue)
> state->residue = residue;
> }
>
> +static inline void dma_set_in_flight_bytes(struct dma_tx_state *state,
> + u32 in_flight_bytes)
> +{
> + if (state)
> + state->in_flight_bytes = in_flight_bytes;
> +}
> +
> struct dmaengine_desc_callback {
> dma_async_tx_callback callback;
> dma_async_tx_callback_result callback_result;
> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> index 0e8b426bbde9..c4c5219030a6 100644
> --- a/include/linux/dmaengine.h
> +++ b/include/linux/dmaengine.h
> @@ -682,11 +682,13 @@ static inline struct dma_async_tx_descriptor *txd_next(struct dma_async_tx_descr
> * @residue: the remaining number of bytes left to transmit
> * on the selected transfer for states DMA_IN_PROGRESS and
> * DMA_PAUSED if this is implemented in the driver, else 0
> + * @in_flight_bytes: amount of data in bytes cached by the DMA.
> */
> struct dma_tx_state {
> dma_cookie_t last;
> dma_cookie_t used;
> u32 residue;
> + u32 in_flight_bytes;

Should we add this here or use the dmaengine_result()

--
~Vinod