Re: [PATCH v2 2/3] dmaengine: rcar-dmac: Add missing dma_descriptor_unmap()

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

On Mon, Oct 12, 2026 at 02:30:22PM +0200, Wolfram Sang wrote:
> From: Koichiro Den <den@valinux.co.jp>
>
> Call dma_descriptor_unmap() right before dma_cookie_complete() in the
> threaded IRQ completion path. Without this, streaming DMA mappings
> attached to the descriptor are never released and may eventually exhaust
> DMA mapping resources (e.g. IOVA with an IOMMU or bounce-buffer slots
> with SWIOTLB), leading to dma_map_* failures.
>
> Also ensure dma_descriptor_unmap() is called in rcar_dmac_chan_reinit()
> (error/terminate path) to avoid the same type of leaks.
>
> Fixes: 87244fe5abdf ("dmaengine: rcar-dmac: Add Renesas R-Car Gen2 DMA Controller (DMAC) driver")
> Signed-off-by: Koichiro Den <den@valinux.co.jp>
> [wsa: moved unmap before cookie completion, added Fixes tag]
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> ---

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

>
> Change since v1:
> * moved unmap before cookie_complete (Sashiko + humans)
> * adjusted commit message
>
>  drivers/dma/sh/rcar-dmac.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
> index 5b54f1c4ce15..78a913c4c0d8 100644
> --- a/drivers/dma/sh/rcar-dmac.c
> +++ b/drivers/dma/sh/rcar-dmac.c
> @@ -844,6 +844,7 @@ static void rcar_dmac_chan_reinit(struct rcar_dmac_chan *chan)
>
>  	list_for_each_entry_safe(desc, _desc, &descs, node) {
>  		list_del(&desc->node);
> +		dma_descriptor_unmap(&desc->async_tx);
>  		rcar_dmac_desc_put(chan, desc);
>  	}
>  }
> @@ -1653,6 +1654,7 @@ static irqreturn_t rcar_dmac_isr_channel_thread(int irq, void *dev)
>  	while (!list_empty(&chan->desc.done)) {
>  		desc = list_first_entry(&chan->desc.done, struct rcar_dmac_desc,
>  					node);
> +		dma_descriptor_unmap(&desc->async_tx);
>  		dma_cookie_complete(&desc->async_tx);
>  		list_del(&desc->node);
>
> --
> 2.53.0
>