Subject: Re: [PATCH v10 02/13] iommu/mediatek-v1: Free the existed fwspec if the master dev already has

From: Mauro Carvalho Chehab <[email-masked]>
Date: Fri, 28 Jan 2022 13:40:55 +0100

Hi Matthias/Yong,

Are you ok if this patch gets merged via the media tree together with the
remaining series, or do you prefer to apply it via SoC tree instead?

Regards,
Mauro

Em Mon, 17 Jan 2022 15:04:59 +0800
Yong Wu <[email-masked]> escreveu:

> When the iommu master device enters of_iommu_xlate, the ops may be
> NULL(iommu dev is defered), then it will initialize the fwspec here:
> 
> [<c0c9c5bc>] (dev_iommu_fwspec_set) from [<c06bda80>]
> (iommu_fwspec_init+0xbc/0xd4)
> [<c06bd9c4>] (iommu_fwspec_init) from [<c06c0db4>]
> (of_iommu_xlate+0x7c/0x12c)
> [<c06c0d38>] (of_iommu_xlate) from [<c06c10e8>]
> (of_iommu_configure+0x144/0x1e8)
> 
> BUT the mtk_iommu_v1.c only supports arm32, the probing flow still is a bit
> weird. We always expect create the fwspec internally. otherwise it will
> enter here and return fail.
> 
> static int mtk_iommu_create_mapping(struct device *dev,
> 				    struct of_phandle_args *args)
> {
>         ...
> 	if (!fwspec) {
> 	        ....
> 	} else if (dev_iommu_fwspec_get(dev)->ops != &mtk_iommu_ops) {
>                 >>>>>>>>>>Enter here. return fail.<<<<<<<<<<<<  
> 		return -EINVAL;
> 	}
> 	...
> }
> 
> Thus, Free the existed fwspec if the master device already has fwspec.
> 
> This issue is reported at:
> https://lore.kernel.org/linux-mediatek/trinity-7d9ebdc9-4849-4d93-bfb5-429dcb4ee449-1626253158870@3c-app-gmx-bs01/
> 
> Reported-by: Frank Wunderlich <[email-masked]>
> Tested-by: Frank Wunderlich <[email-masked]> # BPI-R2/MT7623
> Signed-off-by: Yong Wu <[email-masked]>
> Acked-by: Joerg Roedel <[email-masked]>
> Acked-by: AngeloGioacchino Del Regno <[email-masked]>
> ---
>  drivers/iommu/mtk_iommu_v1.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c
> index be22fcf988ce..1467ba1e4417 100644
> --- a/drivers/iommu/mtk_iommu_v1.c
> +++ b/drivers/iommu/mtk_iommu_v1.c
> @@ -425,6 +425,15 @@ static struct iommu_device *mtk_iommu_probe_device(struct device *dev)
>  	struct mtk_iommu_data *data;
>  	int err, idx = 0;
>  
> +	/*
> +	 * In the deferred case, free the existed fwspec.
> +	 * Always initialize the fwspec internally.
> +	 */
> +	if (fwspec) {
> +		iommu_fwspec_free(dev);
> +		fwspec = dev_iommu_fwspec_get(dev);
> +	}
> +
>  	while (!of_parse_phandle_with_args(dev->of_node, "iommus",
>  					   "#iommu-cells",
>  					   idx, &iommu_spec)) {

Thanks,
Mauro

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