Re: [PATCH 2/4] dmaengine: sh: rcar-dmac: SMMU doesn't need IPMMU workaround

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

On Tue, Aug 25, 2026 at 04:15:44PM +0200, Wolfram Sang wrote:
> R-Car Gen5 doesn't use an IPMMU anymore, but a SMMU. So, the workaround
> for the IPMMU becomes optional. Add a flag to distinguish. No functional
> change.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> ---
>  drivers/dma/sh/rcar-dmac.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
> index cf07c17847d0..9c5210257097 100644
> --- a/drivers/dma/sh/rcar-dmac.c
> +++ b/drivers/dma/sh/rcar-dmac.c
> @@ -219,10 +219,12 @@ struct rcar_dmac {
>   * struct rcar_dmac_of_data - This driver's OF data
>   * @chan_offset_base: DMAC channels base offset
>   * @chan_offset_stride: DMAC channels offset stride
> + * @has_ipmmu: flag telling if DMAC is connected to an IPMMU
>   */
>  struct rcar_dmac_of_data {
>  	u32 chan_offset_base;
>  	u32 chan_offset_stride;
> +	unsigned int has_ipmmu:1;

Nit: most similar case use bool

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

>  };
>
>  /* -----------------------------------------------------------------------------
> @@ -1877,8 +1879,9 @@ static int rcar_dmac_probe(struct platform_device *pdev)
>  	 * can't use it with the IPMMU. As the IOMMU API operates at the device
>  	 * level we can't disable it selectively, so ignore channel 0 for now if
>  	 * the device is part of an IOMMU group.
> +	 * Not applicable if system uses something else than IPMMU like SMMU.
>  	 */
> -	if (device_iommu_mapped(&pdev->dev))
> +	if (data->has_ipmmu && device_iommu_mapped(&pdev->dev))
>  		dmac->channels_mask &= ~BIT(0);
>
>  	dmac->channels = devm_kcalloc(&pdev->dev, dmac->n_channels,
> @@ -2000,11 +2003,13 @@ static void rcar_dmac_shutdown(struct platform_device *pdev)
>  static const struct rcar_dmac_of_data rcar_dmac_data = {
>  	.chan_offset_base = 0x8000,
>  	.chan_offset_stride = 0x80,
> +	.has_ipmmu = 1,
>  };
>
>  static const struct rcar_dmac_of_data rcar_gen4_dmac_data = {
>  	.chan_offset_base = 0x0,
>  	.chan_offset_stride = 0x1000,
> +	.has_ipmmu = 1,
>  };
>
>  static const struct of_device_id rcar_dmac_of_ids[] = {
> --
> 2.47.3
>