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Date:   Mon, 16 May 2022 11:07:21 +0100
From:   Will Deacon <will@kernel.org>
To:     cyndis@kapsi.fi
Cc:     thierry.reding@gmail.com, jonathanh@nvidia.com, joro@8bytes.org,
        robin.murphy@arm.com, robh+dt@kernel.org,
        krzysztof.kozlowski@canonical.com, linux-tegra@vger.kernel.org,
        dri-devel@lists.freedesktop.org, iommu@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        Mikko Perttunen <mperttunen@nvidia.com>
Subject: Re: [PATCH v5 5/9] iommu/arm-smmu: Attach to host1x context device
 bus
Message-ID: <20220516100721.GA1927@willie-the-truck>
References: <20220516085258.1227691-1-cyndis@kapsi.fi>
 <20220516085258.1227691-6-cyndis@kapsi.fi>
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On Mon, May 16, 2022 at 11:52:54AM +0300, cyndis@kapsi.fi wrote:
> From: Mikko Perttunen <mperttunen@nvidia.com>
> 
> Set itself as the IOMMU for the host1x context device bus, containing
> "dummy" devices used for Host1x context isolation.
> 
> Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
> ---
>  drivers/iommu/arm/arm-smmu/arm-smmu.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> index 568cce590ccc..9ff54eaecf81 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> @@ -39,6 +39,7 @@
>  
>  #include <linux/amba/bus.h>
>  #include <linux/fsl/mc.h>
> +#include <linux/host1x_context_bus.h>
>  
>  #include "arm-smmu.h"
>  
> @@ -2053,8 +2054,20 @@ static int arm_smmu_bus_init(struct iommu_ops *ops)
>  			goto err_reset_pci_ops;
>  	}
>  #endif
> +#ifdef CONFIG_TEGRA_HOST1X_CONTEXT_BUS
> +	if (!iommu_present(&host1x_context_device_bus_type)) {
> +		err = bus_set_iommu(&host1x_context_device_bus_type, ops);
> +		if (err)
> +			goto err_reset_fsl_mc_ops;
> +	}
> +#endif
> +
>  	return 0;
>  
> +err_reset_fsl_mc_ops: __maybe_unused;
> +#ifdef CONFIG_FSL_MC_BUS
> +	bus_set_iommu(&fsl_mc_bus_type, NULL);
> +#endif

bus_set_iommu() is going away:

https://lore.kernel.org/r/cover.1650890638.git.robin.murphy@arm.com

Will
>