[PATCH v3 04/34] dmaengine: at_xdmac: move irq bottom half to dmaengine BH

[Frank Li]

On Mon, Aug 10, 2026 at 11:09:05AM -0700, Allen Pais wrote:
> Replace the per-channel tasklet with the shared dmaengine BH helper.
> The handler continues to run in softirq context while dmaengine owns
> the common scheduling and teardown mechanism.
>
> Signed-off-by: Allen Pais <allen.lkml at gmail.com>
> ---

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

>  drivers/dma/at_xdmac.c | 13 ++++++-------
>  1 file changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
> index 901971e8bae6..5a970f9f3831 100644
> --- a/drivers/dma/at_xdmac.c
> +++ b/drivers/dma/at_xdmac.c
> @@ -228,7 +228,6 @@ struct at_xdmac_chan {
>  	u32				save_cndc;
>  	u32				irq_status;
>  	unsigned long			status;
> -	struct tasklet_struct		tasklet;
>  	struct dma_slave_config		sconfig;
>
>  	spinlock_t			lock;
> @@ -1759,9 +1758,9 @@ static void at_xdmac_handle_error(struct at_xdmac_chan *atchan)
>  	/* Then continue with usual descriptor management */
>  }
>
> -static void at_xdmac_tasklet(struct tasklet_struct *t)
> +static void at_xdmac_tasklet(struct dma_chan *chan)
>  {
> -	struct at_xdmac_chan	*atchan = from_tasklet(atchan, t, tasklet);
> +	struct at_xdmac_chan	*atchan = to_at_xdmac_chan(chan);
>  	struct at_xdmac		*atxdmac = to_at_xdmac(atchan->chan.device);
>  	struct at_xdmac_desc	*desc;
>  	struct dma_async_tx_descriptor *txd;
> @@ -1865,7 +1864,7 @@ static irqreturn_t at_xdmac_interrupt(int irq, void *dev_id)
>  			if (atchan->irq_status & (AT_XDMAC_CIS_RBEIS | AT_XDMAC_CIS_WBEIS))
>  				at_xdmac_write(atxdmac, AT_XDMAC_GD, atchan->mask);
>
> -			tasklet_schedule(&atchan->tasklet);
> +			dmaengine_schedule_bh(&atchan->chan);
>  			ret = IRQ_HANDLED;
>  		}
>
> @@ -2317,7 +2316,7 @@ static int at_xdmac_probe(struct platform_device *pdev)
>  		return PTR_ERR(atxdmac->clk);
>  	}
>
> -	/* Do not use dev res to prevent races with tasklet */
> +	/* Do not use devm resources to prevent races with the BH worker */
>  	ret = request_irq(atxdmac->irq, at_xdmac_interrupt, 0, "at_xdmac", atxdmac);
>  	if (ret) {
>  		dev_err(&pdev->dev, "can't request irq\n");
> @@ -2397,7 +2396,7 @@ static int at_xdmac_probe(struct platform_device *pdev)
>  		spin_lock_init(&atchan->lock);
>  		INIT_LIST_HEAD(&atchan->xfers_list);
>  		INIT_LIST_HEAD(&atchan->free_descs_list);
> -		tasklet_setup(&atchan->tasklet, at_xdmac_tasklet);
> +		dmaengine_init_bh(&atchan->chan, at_xdmac_tasklet);
>
>  		/* Clear pending interrupts. */
>  		while (at_xdmac_chan_read(atchan, AT_XDMAC_CIS))
> @@ -2458,7 +2457,7 @@ static void at_xdmac_remove(struct platform_device *pdev)
>  	for (i = 0; i < atxdmac->dma.chancnt; i++) {
>  		struct at_xdmac_chan *atchan = &atxdmac->chan[i];
>
> -		tasklet_kill(&atchan->tasklet);
> +		dmaengine_kill_bh(&atchan->chan);
>  		at_xdmac_free_chan_resources(&atchan->chan);
>  	}
>  }
> --
> 2.43.0
>