Re: [PATCH v3 6/9] dmaengine: sun6i: retire interrupt state before reusing physical channels

[Frank Li <Frank.li@oss.nxp.com>]

On Fri, Oct 23, 2026 at 05:38:25PM -0600, James Hilliard wrote:
> Termination stops a physical channel and drops its owner without masking
> or clearing its interrupt state. A completion latched by the old transfer
> can therefore be delivered to a descriptor installed after reassignment.
>
> Mask and acknowledge the stopped channel's interrupts before releasing
> its ownership, and clear pending status before starting a new descriptor.
> Keep these register updates under the same device lock used to sample and
> acknowledge interrupts in the handler.
>
> Schedule the allocator after termination so pending virtual channels can
> use the released physical channel even when no further interrupt occurs.
>
> Fixes: 555859308723 ("dmaengine: sun6i: Add driver for the Allwinner A31 DMA controller")
> Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
> ---

Reviewed-by: Frank Li <Frank.Li@nxp.com>

>  drivers/dma/sun6i-dma.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
> index 900bb629ba3b..dab17b3863fc 100644
> --- a/drivers/dma/sun6i-dma.c
> +++ b/drivers/dma/sun6i-dma.c
> @@ -501,6 +501,11 @@ static int sun6i_dma_start_desc(struct sun6i_vchan *vchan)
>  	irq_reg = pchan->idx / sdev->cfg->num_channels_per_reg;
>  	irq_offset = pchan->idx % sdev->cfg->num_channels_per_reg;
>
> +	/* Do not deliver a previous transfer's interrupt to this descriptor. */
> +	sun6i_write_irq_stat(sdev, irq_reg,
> +			     (DMA_IRQ_HALF | DMA_IRQ_PKG | DMA_IRQ_QUEUE) <<
> +			     (irq_offset * DMA_IRQ_CHAN_WIDTH));
> +
>  	vchan->irq_type = vchan->cyclic ? DMA_IRQ_PKG : DMA_IRQ_QUEUE;
>
>  	irq_val = sun6i_read_irq_en(sdev, irq_reg);
> @@ -973,6 +978,7 @@ static int sun6i_dma_terminate_all(struct dma_chan *chan)
>  	struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(chan->device);
>  	struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
>  	struct sun6i_pchan *pchan;
> +	u32 irq_reg, irq_shift, irq_mask;
>  	unsigned long flags;
>  	LIST_HEAD(head);
>
> @@ -994,6 +1000,14 @@ static int sun6i_dma_terminate_all(struct dma_chan *chan)
>  		writel(DMA_CHAN_ENABLE_STOP, pchan->base + DMA_CHAN_ENABLE);
>  		writel(DMA_CHAN_PAUSE_RESUME, pchan->base + DMA_CHAN_PAUSE);
>
> +		irq_reg = pchan->idx / sdev->cfg->num_channels_per_reg;
> +		irq_shift = (pchan->idx % sdev->cfg->num_channels_per_reg) *
> +			    DMA_IRQ_CHAN_WIDTH;
> +		irq_mask = (DMA_IRQ_HALF | DMA_IRQ_PKG | DMA_IRQ_QUEUE) << irq_shift;
> +		sun6i_write_irq_en(sdev, irq_reg,
> +				   sun6i_read_irq_en(sdev, irq_reg) & ~irq_mask);
> +		sun6i_write_irq_stat(sdev, irq_reg, irq_mask);
> +
>  		vchan->phy = NULL;
>  		pchan->vchan = NULL;
>  		pchan->desc = NULL;
> @@ -1003,6 +1017,8 @@ static int sun6i_dma_terminate_all(struct dma_chan *chan)
>  	spin_unlock_irqrestore(&sdev->lock, flags);
>
>  	vchan_dma_desc_free_list(&vchan->vc, &head);
> +	if (!atomic_read(&sdev->tasklet_shutdown))
> +		tasklet_schedule(&sdev->task);
>
>  	return 0;
>  }
>
> --
> 2.53.0
>