Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> writes:
> The commit 2895b2cad6e7 ("dmaengine: dw: fix cyclic transfer callbacks")
> re-enabled BLOCK interrupts with regard to make cyclic transfers work. However,
> this change becomes a regression for non-cyclic transfers as interrupt counters
> under stress test had been grown enormously (approximately per 4-5 bytes in the
> UART loop back test).
>
> Taking into consideration above enable BLOCK interrupts if and only if channel
> is programmed to perform cyclic transfer.
>
> Fixes: 2895b2cad6e7 ("dmaengine: dw: fix cyclic transfer callbacks")
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Cc: Mans Rullgard <mans@xxxxxxxxx>
> Cc: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> ---
> drivers/dma/dw/core.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
Acked-by: Mans Rullgard <mans@xxxxxxxxx>
Tested-by: Mans Rullgard <mans@xxxxxxxxx>
> diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c
> index e893318..5ad0ec1 100644
> --- a/drivers/dma/dw/core.c
> +++ b/drivers/dma/dw/core.c
> @@ -156,7 +156,6 @@ static void dwc_initialize(struct dw_dma_chan *dwc)
>
> /* Enable interrupts */
> channel_set_bit(dw, MASK.XFER, dwc->mask);
> - channel_set_bit(dw, MASK.BLOCK, dwc->mask);
> channel_set_bit(dw, MASK.ERROR, dwc->mask);
>
> dwc->initialized = true;
> @@ -588,6 +587,9 @@ static void dwc_handle_cyclic(struct dw_dma *dw, struct dw_dma_chan *dwc,
>
> spin_unlock_irqrestore(&dwc->lock, flags);
> }
> +
> + /* Re-enable interrupts */
> + channel_set_bit(dw, MASK.BLOCK, dwc->mask);
> }
>
> /* ------------------------------------------------------------------------- */
> @@ -618,11 +620,8 @@ static void dw_dma_tasklet(unsigned long data)
> dwc_scan_descriptors(dw, dwc);
> }
>
> - /*
> - * Re-enable interrupts.
> - */
> + /* Re-enable interrupts */
> channel_set_bit(dw, MASK.XFER, dw->all_chan_mask);
> - channel_set_bit(dw, MASK.BLOCK, dw->all_chan_mask);
> channel_set_bit(dw, MASK.ERROR, dw->all_chan_mask);
> }
>
> @@ -1261,6 +1260,7 @@ static void dwc_free_chan_resources(struct dma_chan *chan)
> int dw_dma_cyclic_start(struct dma_chan *chan)
> {
> struct dw_dma_chan *dwc = to_dw_dma_chan(chan);
> + struct dw_dma *dw = to_dw_dma(chan->device);
> unsigned long flags;
>
> if (!test_bit(DW_DMA_IS_CYCLIC, &dwc->flags)) {
> @@ -1269,7 +1269,12 @@ int dw_dma_cyclic_start(struct dma_chan *chan)
> }
>
> spin_lock_irqsave(&dwc->lock, flags);
> +
> + /* Enable interrupts to perform cyclic transfer */
> + channel_set_bit(dw, MASK.BLOCK, dwc->mask);
> +
> dwc_dostart(dwc, dwc->cdesc->desc[0]);
> +
> spin_unlock_irqrestore(&dwc->lock, flags);
>
> return 0;
> --
> 2.7.0
>
--
Måns Rullgård
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