Re: [PATCH v3 18/34] dmaengine: xgene-dma: wire descriptor cleanup to dmaengine BH

[Frank Li]

On Mon, Aug 10, 2026 at 11:09:19AM -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@xxxxxxxxx>
> ---

Reviewed-by: Frank Li <Frank.Li@xxxxxxx>

>  drivers/dma/xgene-dma.c | 19 +++++++++----------
>  1 file changed, 9 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/dma/xgene-dma.c b/drivers/dma/xgene-dma.c
> index fa1173e49900..bdeed908e37a 100644
> --- a/drivers/dma/xgene-dma.c
> +++ b/drivers/dma/xgene-dma.c
> @@ -260,7 +260,6 @@ struct xgene_dma_desc_sw {
>   *	These descriptors have already had their cleanup actions run. They
>   *	are waiting for the ACK bit to be set by the async tx API.
>   * @desc_pool: descriptor pool for DMA operations
> - * @tasklet: bottom half where all completed descriptors cleans
>   * @tx_ring: transmit ring descriptor that we use to prepare actual
>   *	descriptors for further executions
>   * @rx_ring: receive ring descriptor that we use to get completed DMA
> @@ -280,7 +279,6 @@ struct xgene_dma_chan {
>  	struct list_head ld_running;
>  	struct list_head ld_completed;
>  	struct dma_pool *desc_pool;
> -	struct tasklet_struct tasklet;
>  	struct xgene_dma_ring tx_ring;
>  	struct xgene_dma_ring rx_ring;
>  };
> @@ -975,9 +973,10 @@ static enum dma_status xgene_dma_tx_status(struct dma_chan *dchan,
>  	return dma_cookie_status(dchan, cookie, txstate);
>  }
>
> -static void xgene_dma_tasklet_cb(struct tasklet_struct *t)
> +static void xgene_dma_tasklet_cb(struct dma_chan *c)
>  {
> -	struct xgene_dma_chan *chan = from_tasklet(chan, t, tasklet);
> +	struct xgene_dma_chan *chan = container_of(c, struct xgene_dma_chan,
> +						   dma_chan);
>
>  	/* Run all cleanup for descriptors which have been completed */
>  	xgene_dma_cleanup_descriptors(chan);
> @@ -999,11 +998,11 @@ static irqreturn_t xgene_dma_chan_ring_isr(int irq, void *id)
>  	disable_irq_nosync(chan->rx_irq);
>
>  	/*
> -	 * Schedule the tasklet to handle all cleanup of the current
> +	 * Schedule the bottom half to handle all cleanup of the current
>  	 * transaction. It will start a new transaction if there is
>  	 * one pending.
>  	 */
> -	tasklet_schedule(&chan->tasklet);
> +	dmaengine_schedule_bh(&chan->dma_chan);
>
>  	return IRQ_HANDLED;
>  }
> @@ -1539,7 +1538,7 @@ static int xgene_dma_async_register(struct xgene_dma *pdma, int id)
>  	INIT_LIST_HEAD(&chan->ld_pending);
>  	INIT_LIST_HEAD(&chan->ld_running);
>  	INIT_LIST_HEAD(&chan->ld_completed);
> -	tasklet_setup(&chan->tasklet, xgene_dma_tasklet_cb);
> +	dmaengine_init_bh(&chan->dma_chan, xgene_dma_tasklet_cb);
>
>  	chan->pending = 0;
>  	chan->desc_pool = NULL;
> @@ -1556,7 +1555,7 @@ static int xgene_dma_async_register(struct xgene_dma *pdma, int id)
>  	ret = dma_async_device_register(dma_dev);
>  	if (ret) {
>  		chan_err(chan, "Failed to register async device %d", ret);
> -		tasklet_kill(&chan->tasklet);
> +		dmaengine_kill_bh(&chan->dma_chan);
>
>  		return ret;
>  	}
> @@ -1579,7 +1578,7 @@ static int xgene_dma_init_async(struct xgene_dma *pdma)
>  		if (ret) {
>  			for (j = 0; j < i; j++) {
>  				dma_async_device_unregister(&pdma->dma_dev[j]);
> -				tasklet_kill(&pdma->chan[j].tasklet);
> +				dmaengine_kill_bh(&pdma->chan[j].dma_chan);
>  			}
>
>  			return ret;
> @@ -1790,7 +1789,7 @@ static void xgene_dma_remove(struct platform_device *pdev)
>
>  	for (i = 0; i < XGENE_DMA_MAX_CHANNEL; i++) {
>  		chan = &pdma->chan[i];
> -		tasklet_kill(&chan->tasklet);
> +		dmaengine_kill_bh(&chan->dma_chan);
>  		xgene_dma_delete_chan_rings(chan);
>  	}
>
> --
> 2.43.0
>