Hi Muhammad,
Thank you for the patch.
On Tuesday 29 September 2015 22:44:44 hamzahfrq.sub@xxxxxxxxx wrote:
> From: Muhammad Hamza Farooq <mfarooq@xxxxxxxxxxx>
>
> Signed-off-by: Muhammad Hamza Farooq <mfarooq@xxxxxxxxxxx>
> ---
> drivers/dma/sh/rcar-dmac.c | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
>
> diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
> index 2b28291..c7cd4ed 100644
> --- a/drivers/dma/sh/rcar-dmac.c
> +++ b/drivers/dma/sh/rcar-dmac.c
> @@ -774,6 +774,26 @@ static void rcar_dmac_chan_reinit(struct rcar_dmac_chan
> *chan) }
> }
>
> +static int rcar_dmac_chan_pause(struct dma_chan *chan)
> +{
> + u32 chcr;
> + int ret;
> + unsigned long flags;
> + struct rcar_dmac_chan *rchan = to_rcar_dmac_chan(chan);
> +
> + spin_lock_irqsave(&rchan->lock, flags);
> +
> + chcr = rcar_dmac_chan_read(rchan, RCAR_DMACHCR);
> + chcr &= ~RCAR_DMACHCR_DE;
> + rcar_dmac_chan_write(rchan, RCAR_DMACHCR, chcr);
> + ret = rcar_dmac_wait_stop(rchan);
The DMA engine API documents the pause operation as stopping DMA transfers in
a resumable way without data loss. Doesn't stopping the transfer forcefully
like this result in incomplete transfers and thus data loss ? Shouldn't we
instead signal the pause request to the interrupt handler to avoid starting
the next transfer and wait for the end of the current transfer ?
> +
> + spin_unlock_irqrestore(&rchan->lock, flags);
> +
> + WARN_ON(ret < 0);
> + return ret;
> +}
> +
> static void rcar_dmac_stop(struct rcar_dmac *dmac)
> {
> rcar_dmac_write(dmac, RCAR_DMAOR, 0);
> @@ -1740,6 +1760,7 @@ static int rcar_dmac_probe(struct platform_device
> *pdev) engine->device_prep_slave_sg = rcar_dmac_prep_slave_sg;
> engine->device_prep_dma_cyclic = rcar_dmac_prep_dma_cyclic;
> engine->device_config = rcar_dmac_device_config;
> + engine->device_pause = rcar_dmac_chan_pause;
> engine->device_terminate_all = rcar_dmac_chan_terminate_all;
> engine->device_tx_status = rcar_dmac_tx_status;
> engine->device_issue_pending = rcar_dmac_issue_pending;
--
Regards,
Laurent Pinchart
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