Re: [PATCH v15 4/5] iommu/arm-smmu: introduction of ACTLR for custom prefetcher settings

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On 9/20/2024 9:50 PM, Dmitry Baryshkov wrote:
On Fri, Sep 20, 2024 at 09:28:12PM GMT, Bibek Kumar Patro 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@xxxxxxxxxxx>
---
  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..4ac272d05843 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_notice(dev, "no ACTLR settings present\n");

dev_dbg() or even dev_vdbg(), please. We do not want to spam people with
messages about a perfectly normal behaviour.

LGTM otherwise.

Ack, thanks Dmitry for the suggestion.
I was actually wondering if to broadcast this message
over the logs through dev_notice or give a option to
print it in debug level through dev_dbg.

But I'm inline with your suggestion now, will switch
to dev_dbg for this message.

Thanks & regards,
Bibek



+		return;
+	}
+
+	arm_smmu_cb_write(smmu, cbndx, ARM_SMMU_CB_ACTLR, (u64)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






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