linux-kernel - Re: [PATCH v5 5/9] iommu/arm-smmu: Attach to host1x context device bus

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Date:   Mon, 16 May 2022 13:13:27 +0300
From:   Mikko Perttunen <cyndis@...si.fi>
To:     Will Deacon <will@...nel.org>
Cc:     thierry.reding@...il.com, jonathanh@...dia.com, joro@...tes.org,
        robin.murphy@....com, robh+dt@...nel.org,
        krzysztof.kozlowski@...onical.com, linux-tegra@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Mikko Perttunen <mperttunen@...dia.com>
Subject: Re: [PATCH v5 5/9] iommu/arm-smmu: Attach to host1x context device
 bus

On 5/16/22 13:07, Will Deacon wrote:
> On Mon, May 16, 2022 at 11:52:54AM +0300, cyndis@...si.fi wrote:
>> From: Mikko Perttunen <mperttunen@...dia.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@...dia.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

Thanks for the heads-up. Robin had pointed out that this work was 
ongoing but I hadn't seen the patches yet. I'll look into it.

Mikko

>>