[PATCH V7] dmaengine: bcm2835-dma: Prevent suspend if DMA channel is busy

[Stefan Wahren]

Am 04.12.24 um 17:55 schrieb Stefan Wahren:
> bcm2835-dma provides the service to others, so it should suspend
> late and resume early. Suspend should be prevented in case a DMA
> channel is still busy.
>
> Signed-off-by: Stefan Wahren <wahrenst at gmx.net>
gentle ping ...
> ---
>   drivers/dma/bcm2835-dma.c | 22 ++++++++++++++++++++++
>   1 file changed, 22 insertions(+)
>
> Changes in V7:
> - improve patch title and changelog
> - add explaining comment and drop warning in suspend
> - drop empty resume callback
>
> Changes in V6:
> - split out of series because there is no dependency
>
> diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
> index 7ba52dee40a9..20b10c15c696 100644
> --- a/drivers/dma/bcm2835-dma.c
> +++ b/drivers/dma/bcm2835-dma.c
> @@ -875,6 +875,27 @@ static struct dma_chan *bcm2835_dma_xlate(struct of_phandle_args *spec,
>   	return chan;
>   }
>
> +static int bcm2835_dma_suspend_late(struct device *dev)
> +{
> +	struct bcm2835_dmadev *od = dev_get_drvdata(dev);
> +	struct bcm2835_chan *c, *next;
> +
> +	list_for_each_entry_safe(c, next, &od->ddev.channels,
> +				 vc.chan.device_node) {
> +		void __iomem *chan_base = c->chan_base;
> +
> +		/* Check if DMA channel is busy */
> +		if (readl(chan_base + BCM2835_DMA_ADDR))
> +			return -EBUSY;
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct dev_pm_ops bcm2835_dma_pm_ops = {
> +	SET_LATE_SYSTEM_SLEEP_PM_OPS(bcm2835_dma_suspend_late, NULL)
> +};
> +
>   static int bcm2835_dma_probe(struct platform_device *pdev)
>   {
>   	struct bcm2835_dmadev *od;
> @@ -1033,6 +1054,7 @@ static struct platform_driver bcm2835_dma_driver = {
>   	.driver = {
>   		.name = "bcm2835-dma",
>   		.of_match_table = of_match_ptr(bcm2835_dma_of_match),
> +		.pm = pm_ptr(&bcm2835_dma_pm_ops),
>   	},
>   };
>
> --
> 2.34.1
>