Re: [PATCH v3 08/34] dmaengine: imx-dma: flip per-chan tasklet to dmaengine BH

[Frank Li]

On Mon, Aug 10, 2026 at 11:09:09AM -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/imx-dma.c | 26 +++++++++++++-------------
>  1 file changed, 13 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/dma/imx-dma.c b/drivers/dma/imx-dma.c
> index 81c6276436f8..308fe407fe16 100644
> --- a/drivers/dma/imx-dma.c
> +++ b/drivers/dma/imx-dma.c
> @@ -145,7 +145,6 @@ struct imxdma_channel {
>  	struct imxdma_engine		*imxdma;
>  	unsigned int			channel;
>
> -	struct tasklet_struct		dma_tasklet;
>  	struct list_head		ld_free;
>  	struct list_head		ld_queue;
>  	struct list_head		ld_active;
> @@ -344,8 +343,8 @@ static void imxdma_watchdog(struct timer_list *t)
>
>  	imx_dmav1_writel(imxdma, 0, DMA_CCR(channel));
>
> -	/* Tasklet watchdog error handler */
> -	tasklet_schedule(&imxdmac->dma_tasklet);
> +	/* BH watchdog error handler */
> +	dmaengine_schedule_bh(&imxdmac->chan);
>  	dev_dbg(imxdma->dev, "channel %d: watchdog timeout!\n",
>  		imxdmac->channel);
>  }
> @@ -390,8 +389,8 @@ static irqreturn_t imxdma_err_handler(int irq, void *dev_id)
>  			imx_dmav1_writel(imxdma, 1 << i, DMA_DBOSR);
>  			errcode |= IMX_DMA_ERR_BUFFER;
>  		}
> -		/* Tasklet error handler */
> -		tasklet_schedule(&imxdma->channel[i].dma_tasklet);
> +		/* BH error handler */
> +		dmaengine_schedule_bh(&imxdma->channel[i].chan);
>
>  		dev_warn(imxdma->dev,
>  			 "DMA timeout on channel %d -%s%s%s%s\n", i,
> @@ -448,8 +447,8 @@ static void dma_irq_handle_channel(struct imxdma_channel *imxdmac)
>  			imx_dmav1_writel(imxdma, tmp, DMA_CCR(chno));
>
>  			if (imxdma_chan_is_doing_cyclic(imxdmac))
> -				/* Tasklet progression */
> -				tasklet_schedule(&imxdmac->dma_tasklet);
> +				/* BH progression */
> +				dmaengine_schedule_bh(&imxdmac->chan);
>
>  			return;
>  		}
> @@ -462,8 +461,8 @@ static void dma_irq_handle_channel(struct imxdma_channel *imxdmac)
>
>  out:
>  	imx_dmav1_writel(imxdma, 0, DMA_CCR(chno));
> -	/* Tasklet irq */
> -	tasklet_schedule(&imxdmac->dma_tasklet);
> +	/* Schedule the IRQ BH */
> +	dmaengine_schedule_bh(&imxdmac->chan);
>  }
>
>  static irqreturn_t dma_irq_handler(int irq, void *dev_id)
> @@ -592,9 +591,10 @@ static int imxdma_xfer_desc(struct imxdma_desc *d)
>  	return 0;
>  }
>
> -static void imxdma_tasklet(struct tasklet_struct *t)
> +static void imxdma_tasklet(struct dma_chan *chan)
>  {
> -	struct imxdma_channel *imxdmac = from_tasklet(imxdmac, t, dma_tasklet);
> +	struct imxdma_channel *imxdmac = container_of(chan, struct imxdma_channel,
> +						      chan);
>  	struct imxdma_engine *imxdma = imxdmac->imxdma;
>  	struct imxdma_desc *desc, *next_desc;
>  	unsigned long flags;
> @@ -1142,7 +1142,7 @@ static int __init imxdma_probe(struct platform_device *pdev)
>  		INIT_LIST_HEAD(&imxdmac->ld_free);
>  		INIT_LIST_HEAD(&imxdmac->ld_active);
>
> -		tasklet_setup(&imxdmac->dma_tasklet, imxdma_tasklet);
> +		dmaengine_init_bh(&imxdmac->chan, imxdma_tasklet);
>  		imxdmac->chan.device = &imxdma->dma_device;
>  		dma_cookie_init(&imxdmac->chan);
>  		imxdmac->channel = i;
> @@ -1211,7 +1211,7 @@ static void imxdma_free_irq(struct platform_device *pdev, struct imxdma_engine *
>  		if (!is_imx1_dma(imxdma))
>  			disable_irq(imxdmac->irq);
>
> -		tasklet_kill(&imxdmac->dma_tasklet);
> +		dmaengine_kill_bh(&imxdmac->chan);
>  	}
>  }
>
> --
> 2.43.0
>