Hi,

On Wed 13 May 20, 16:07, Maxime Ripard wrote:
> The main DRM device is actually a virtual device so it doesn't have the
> iommus property, which is instead on the DMA masters, in this case the
> mixers.
> 
> Add a call to of_dma_configure with the mixers DT node but on the DRM
> virtual device to configure it in the same way than the mixers.

Although I'm not very familiar with the DMA API, this looks legit to me and
matches what's already done in sun4i_backend for the interconnect. So:

Reviewed-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>

Cheers,

Paul

> Signed-off-by: Maxime Ripard <maxime@cerno.tech>
> ---
>  drivers/gpu/drm/sun4i/sun8i_mixer.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/gpu/drm/sun4i/sun8i_mixer.c b/drivers/gpu/drm/sun4i/sun8i_mixer.c
> index 56cc037fd312..cc4fb916318f 100644
> --- a/drivers/gpu/drm/sun4i/sun8i_mixer.c
> +++ b/drivers/gpu/drm/sun4i/sun8i_mixer.c
> @@ -363,6 +363,19 @@ static int sun8i_mixer_bind(struct device *dev, struct device *master,
>  	mixer->engine.ops = &sun8i_engine_ops;
>  	mixer->engine.node = dev->of_node;
>  
> +	if (of_find_property(dev->of_node, "iommus", NULL)) {
> +		/*
> +		 * This assume we have the same DMA constraints for
> +		 * all our the mixers in our pipeline. This sounds
> +		 * bad, but it has always been the case for us, and
> +		 * DRM doesn't do per-device allocation either, so we
> +		 * would need to fix DRM first...
> +		 */
> +		ret = of_dma_configure(drm->dev, dev->of_node, true);
> +		if (ret)
> +			return ret;
> +	}
> +
>  	/*
>  	 * While this function can fail, we shouldn't do anything
>  	 * if this happens. Some early DE2 DT entries don't provide
> -- 
> git-series 0.9.1
> 
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-- 
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com