Re: [PATCH v16 4/5] iommu/arm-smmu: introduction of ACTLR for custom prefetcher settings

Rob Clark
2024-10-28T21:24:16Z

On Tue, Oct 8, 2024 at 5:55 AM Bibek Kumar Patro
<quic_bibekkum@quicinc.com> wrote:
>
> Currently in Qualcomm SoCs the default prefetch is set to 1 which allows
> the TLB to fetch just the next page table. MMU-500 features ACTLR
> register which is implementation defined and is used for Qualcomm SoCs
> to have a custom prefetch setting enabling TLB to prefetch the next set
> of page tables accordingly allowing for faster translations.
>
> ACTLR value is unique for each SMR (Stream matching register) and stored
> in a pre-populated table. This value is set to the register during
> context bank initialisation.
>
> Signed-off-by: Bibek Kumar Patro <quic_bibekkum@quicinc.com>

Reviewed-by: Rob Clark <robdclark@gmail.com>

> ---
> drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 26 ++++++++++++++++++++++
> drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h | 1 +
> 2 files changed, 27 insertions(+)
>
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> index 38ac9cab763b..2d2c1e75632c 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> @@ -252,6 +252,20 @@ static bool qcom_adreno_can_do_ttbr1(struct arm_smmu_device *smmu)
> return true;
> }
>
> +static void qcom_smmu_set_actlr_dev(struct device *dev, struct arm_smmu_device *smmu, int cbndx,
> + const struct of_device_id *client_match)
> +{
> + const struct of_device_id *match =
> + of_match_device(client_match, dev);
> +
> + if (!match) {
> + dev_dbg(dev, "no ACTLR settings present\n");
> + return;
> + }
> +
> + arm_smmu_cb_write(smmu, cbndx, ARM_SMMU_CB_ACTLR, (unsigned long)match->data);
> +}
> +
> static int qcom_adreno_smmu_init_context(struct arm_smmu_domain *smmu_domain,
> struct io_pgtable_cfg *pgtbl_cfg, struct device *dev)
> {
> @@ -316,8 +330,20 @@ static const struct of_device_id qcom_smmu_client_of_match[] __maybe_unused = {
> static int qcom_smmu_init_context(struct arm_smmu_domain *smmu_domain,
> struct io_pgtable_cfg *pgtbl_cfg, struct device *dev)
> {
> + struct arm_smmu_device *smmu = smmu_domain->smmu;
> + struct qcom_smmu *qsmmu = to_qcom_smmu(smmu);
> + const struct of_device_id *client_match;
> + int cbndx = smmu_domain->cfg.cbndx;
> +
> smmu_domain->cfg.flush_walk_prefer_tlbiasid = true;
>
> + client_match = qsmmu->data->client_match;
> +
> + if (!client_match)
> + return 0;
> +
> + qcom_smmu_set_actlr_dev(dev, smmu, cbndx, client_match);
> +
> return 0;
> }
>
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h
> index b55cd3e3ae48..8addd453f5f1 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h
> @@ -28,6 +28,7 @@ struct qcom_smmu_match_data {
> const struct qcom_smmu_config *cfg;
> const struct arm_smmu_impl *impl;
> const struct arm_smmu_impl *adreno_impl;
> + const struct of_device_id * const client_match;
> };
>
> irqreturn_t qcom_smmu_context_fault(int irq, void *dev);
> --
> 2.34.1
>