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From: Will Deacon <will.deacon@arm.com>
To: Olav Haugan <ohaugan@codeaurora.org>
Cc: "mitchelh@codeaurora.org" <mitchelh@codeaurora.org>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"linux-arm-msm@vger.kernel.org" <linux-arm-msm@vger.kernel.org>
Subject: Re: [PATCH v2 2/2] iommu/arm-smmu: Do not access non-existing SMR registers
Date: Wed, 6 Aug 2014 11:19:48 +0100	[thread overview]
Message-ID: <20140806101948.GD23882@arm.com> (raw)
In-Reply-To: <1407175263-10699-3-git-send-email-ohaugan@codeaurora.org>

Hi Olav,

On Mon, Aug 04, 2014 at 07:01:03PM +0100, Olav Haugan wrote:
> The SMR registers do not exist when stream matching is not
> supported by the hardware. Avoid writing to this register if not needed.
> 
> Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
> ---
>  drivers/iommu/arm-smmu.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index c16431f..1f3a5b3 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -1731,7 +1731,10 @@ static void arm_smmu_device_reset(struct arm_smmu_device *smmu)
>  
>  	/* Mark all SMRn as invalid and all S2CRn as bypass */
>  	for (i = 0; i < smmu->num_mapping_groups; ++i) {
> -		writel_relaxed(~SMR_VALID, gr0_base + ARM_SMMU_GR0_SMR(i));
> +		if (smmu->features & ARM_SMMU_FEAT_STREAM_MATCH) {
> +			writel_relaxed(~SMR_VALID,
> +					gr0_base + ARM_SMMU_GR0_SMR(i));
> +		}
>  		writel_relaxed(S2CR_TYPE_BYPASS,
>  			gr0_base + ARM_SMMU_GR0_S2CR(i));

smmu->num_mapping_groups should be zero for an SMMU that doesn't include
the SMR registers, so I don't think this change is needed. Are you seeing
problems with real hardware?

Will

WARNING: multiple messages have this Message-ID
From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 2/2] iommu/arm-smmu: Do not access non-existing SMR registers
Date: Wed, 6 Aug 2014 11:19:48 +0100	[thread overview]
Message-ID: <20140806101948.GD23882@arm.com> (raw)
In-Reply-To: <1407175263-10699-3-git-send-email-ohaugan@codeaurora.org>

Hi Olav,

On Mon, Aug 04, 2014 at 07:01:03PM +0100, Olav Haugan wrote:
> The SMR registers do not exist when stream matching is not
> supported by the hardware. Avoid writing to this register if not needed.
> 
> Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
> ---
>  drivers/iommu/arm-smmu.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index c16431f..1f3a5b3 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -1731,7 +1731,10 @@ static void arm_smmu_device_reset(struct arm_smmu_device *smmu)
>  
>  	/* Mark all SMRn as invalid and all S2CRn as bypass */
>  	for (i = 0; i < smmu->num_mapping_groups; ++i) {
> -		writel_relaxed(~SMR_VALID, gr0_base + ARM_SMMU_GR0_SMR(i));
> +		if (smmu->features & ARM_SMMU_FEAT_STREAM_MATCH) {
> +			writel_relaxed(~SMR_VALID,
> +					gr0_base + ARM_SMMU_GR0_SMR(i));
> +		}
>  		writel_relaxed(S2CR_TYPE_BYPASS,
>  			gr0_base + ARM_SMMU_GR0_S2CR(i));

smmu->num_mapping_groups should be zero for an SMMU that doesn't include
the SMR registers, so I don't think this change is needed. Are you seeing
problems with real hardware?

Will

  reply	other threads:[~2014-08-06 10:20 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-08-04 18:01 [PATCH v2 0/2] arm-smmu fixes for CBn_TCR and S2CR/SMR programming Olav Haugan
2014-08-04 18:01 ` Olav Haugan
2014-08-04 18:01 ` [PATCH v2 1/2] iommu/arm-smmu: Fix programming of SMMU_CBn_TCR for stage 1 Olav Haugan
2014-08-04 18:01   ` Olav Haugan
2014-08-04 18:01 ` [PATCH v2 2/2] iommu/arm-smmu: Do not access non-existing SMR registers Olav Haugan
2014-08-04 18:01   ` Olav Haugan
2014-08-06 10:19   ` Will Deacon [this message]
2014-08-06 10:19     ` Will Deacon
2014-08-06 16:44     ` Olav Haugan
2014-08-06 16:44       ` Olav Haugan
     [not found]       ` <53E25B76.6090208-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
2014-08-06 17:35         ` Will Deacon
2014-08-06 17:35           ` Will Deacon
     [not found]           ` <20140806173518.GG25953-5wv7dgnIgG8@public.gmane.org>
2014-08-06 23:34             ` Olav Haugan
2014-08-06 23:34               ` Olav Haugan
2014-08-07  9:22               ` Will Deacon
2014-08-07  9:22                 ` Will Deacon
     [not found]                 ` <20140807092254.GH13703-5wv7dgnIgG8@public.gmane.org>
2014-08-08 18:51                   ` Olav Haugan
2014-08-08 18:51                     ` Olav Haugan

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