On 24-09-18, 16:00, 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
this looks okay to me, but not really up for 'cached', better
alternates?
Also we need to update Documentation for this..
>
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx>
> ---
> drivers/dma/dmaengine.h | 7 +++++++
> include/linux/dmaengine.h | 2 ++
> 2 files changed, 9 insertions(+)
>
> diff --git a/drivers/dma/dmaengine.h b/drivers/dma/dmaengine.h
> index 501c0b063f85..80214270b70e 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->cached = 0;
> }
> return dma_async_is_complete(cookie, complete, used);
> }
> @@ -87,6 +88,12 @@ static inline void dma_set_residue(struct dma_tx_state *state, u32 residue)
> state->residue = residue;
> }
>
> +static inline void dma_set_cached(struct dma_tx_state *state, u32 cached)
> +{
> + if (state)
> + state->cached = cached;
> +}
> +
> 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 10ff71b13eef..16c9d021988a 100644
> --- a/include/linux/dmaengine.h
> +++ b/include/linux/dmaengine.h
> @@ -701,11 +701,13 @@ 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
> + * @cached: amount of data in bytes cached by the DMA.
> */
> struct dma_tx_state {
> dma_cookie_t last;
> dma_cookie_t used;
> u32 residue;
> + u32 cached;
> };
>
> /**
> --
> Peter
>
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
--
~Vinod
