linux-kernel - Re: [PATCH v7 4/5] iommu/arm-smmu: add ACTLR data and support for SM8550

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Date: Wed, 10 Jan 2024 10:05:22 +0530
From: Pavan Kondeti <quic_pkondeti@...cinc.com>
To: Bibek Kumar Patro <quic_bibekkum@...cinc.com>
CC: <will@...nel.org>, <robin.murphy@....com>, <joro@...tes.org>,
        <dmitry.baryshkov@...aro.org>, <konrad.dybcio@...aro.org>,
        <jsnitsel@...hat.com>, <quic_bjorande@...cinc.com>, <mani@...nel.org>,
        <quic_eberman@...cinc.com>, <robdclark@...omium.org>,
        <u.kleine-koenig@...gutronix.de>, <robh@...nel.org>,
        <vladimir.oltean@....com>, <quic_pkondeti@...cinc.com>,
        <quic_molvera@...cinc.com>, <linux-arm-msm@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <iommu@...ts.linux.dev>,
        <linux-kernel@...r.kernel.org>, <qipl.kernel.upstream@...cinc.com>
Subject: Re: [PATCH v7 4/5] iommu/arm-smmu: add ACTLR data and support for
 SM8550

On Tue, Jan 09, 2024 at 05:12:19PM +0530, Bibek Kumar Patro wrote:
> +static const struct actlr_variant sm8550_actlr[] = {
> +	{ sm8550_apps_actlr_cfg, 0x15000000 },
> +	{ sm8550_gfx_actlr_cfg, 0x03da0000 },
> +	{},
> +};
> +
>  static struct qcom_smmu *to_qcom_smmu(struct arm_smmu_device *smmu)
>  {
>  	return container_of(smmu, struct qcom_smmu, smmu);
> @@ -597,6 +673,14 @@ static const struct qcom_smmu_match_data sdm845_smmu_500_data = {
>  	/* Also no debug configuration. */
>  };
> 
> +
> +static const struct qcom_smmu_match_data sm8550_smmu_500_impl0_data = {
> +	.impl = &qcom_smmu_500_impl,
> +	.adreno_impl = &qcom_adreno_smmu_500_impl,
> +	.cfg = &qcom_smmu_impl0_cfg,
> +	.actlrvar = sm8550_actlr,
> +};
> +

I wish there is Rust like struct update syntax possible here. All we need
here is to update qcom_smmu_match_data::actlrvar member here to the generic
qcom_smmu_500_impl0_data struct data.

>  static const struct qcom_smmu_match_data qcom_smmu_500_impl0_data = {
>  	.impl = &qcom_smmu_500_impl,
>  	.adreno_impl = &qcom_adreno_smmu_500_impl,
> @@ -631,6 +715,7 @@ static const struct of_device_id __maybe_unused qcom_smmu_impl_of_match[] = {
>  	{ .compatible = "qcom,sm8250-smmu-500", .data = &qcom_smmu_500_impl0_data },
>  	{ .compatible = "qcom,sm8350-smmu-500", .data = &qcom_smmu_500_impl0_data },
>  	{ .compatible = "qcom,sm8450-smmu-500", .data = &qcom_smmu_500_impl0_data },
> +	{ .compatible = "qcom,sm8550-smmu-500", .data = &sm8550_smmu_500_impl0_data },
>  	{ .compatible = "qcom,smmu-500", .data = &qcom_smmu_500_impl0_data },
>  	{ }
>  };

Given that ACTLR data is different across SoCs, would it be a good idea
to decouple it from the qcom_smmu_match_data struct and directly get it
via of_device_is_compatible() from context init functions.  The ACTLR
data will have a compatible string associated with it, we lookup for the
device compatible in this table and select the ACTLR accordingly. This
way, we don't need to add more entries to qcom_smmu_impl_of_match and
keep using the "qcom,smmu-500" for driver match data. 

I have made this suggestion to keep the rule introduced in commit
80b71080720e ("iommu/arm-smmu-qcom: Add generic qcom,smmu-500 match
entry") relavant. I will let Dmitry to provide the guidance here.

Thanks,
Pavan