Re: [PATCH v7 3/5] iommu/arm-smmu: introduction of ACTLR for custom prefetcher settings

[Bibek Kumar Patro]

On 1/10/2024 11:26 PM, Konrad Dybcio wrote:
> On 1/10/24 13:55, Bibek Kumar Patro wrote:
> > On 1/10/2024 4:46 PM, Bibek Kumar Patro wrote:
> > > On 1/10/2024 9:36 AM, Pavan Kondeti wrote:
> >
> > [...]
> >
> > > > > @@ -274,6 +321,21 @@ 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 actlr_variant *actlrvar;
> > > > > +    int cbndx = smmu_domain->cfg.cbndx;
> > > > > +
> > > > > +    if (qsmmu->data->actlrvar) {
> > > > > +        actlrvar = qsmmu->data->actlrvar;
> > > > > +        for (; actlrvar->io_start; actlrvar++) {
> > > > > +            if (actlrvar->io_start == smmu->ioaddr) {
> > > > > +                qcom_smmu_set_actlr(dev, smmu, cbndx, 
> > > > > actlrvar->actlrcfg);
> > > > > +                break;
> > > > > +            }
> > > > > +        }
> > > > > +    }
> > > > > +
> > > >
> > > > This block and the one in qcom_adreno_smmu_init_context() are exactly
> > > > the same. Possible to do some refactoring?
> > >
> > > I will check if this repeated blocks can be accomodated this into 
> > > qcom_smmu_set_actlr function if that would be fine.
> >
> > Also adding to this, this might increase the number of indentation 
> > inside qcom_smmu_set_actlr as well, to around 5. So wouldn't this
> > be an issue?
>
> By the way, we can refactor this:
>
> if (qsmmu->data->actlrvar) {
>      actlrvar = qsmmu->data->actlrvar;
>      for (; actlrvar->io_start; actlrvar++) {
>          if (actlrvar->io_start == smmu->ioaddr) {
>              qcom_smmu_set_actlr(dev, smmu, cbndx, actlrvar->actlrcfg);
>              break;
>          }
>      }
> }
>
> into
>
> // add const u8 num_actlrcfgs to struct actrl_variant to
> // save on sentinel space:
> //   sizeof(u8) < sizeof(ptr) + sizeof(resource_size_t)

Git it, Would it be better to add this in struct qcom_smmu_match_data ?
Posted a sample below.

> [declarations]
> const struct actlr_variant *actlrvar = qsmmu->data->actlrvar;
> int i;
>
> [rest of the functions]
>
> if (!actlrvar)
>      return 0;
>  > for (i = 0; i < actrlvar->num_actrlcfgs; i++) {
>      if (actlrvar[i].io_start == smmu->ioaddr) {
>          qcom_smmu_set_actlr(dev, smmu, cbndx, actlrvar->actlrcfg);
>          break;
>      }
> }
>  > Saving both on .TEXT size and indentation levels :)
Thanks for this suggestion Konrad, will try to implement this, as it 
would reduce the indent levels to good extent.
Would something like this be okay?

static int qcom_smmu_init_context(struct arm_smmu_domain *smmu_domain,
 	struct qcom_smmu *qsmmu = to_qcom_smmu(smmu);
 	const struct actlr_variant *actlrvar;
 	int cbndx = smmu_domain->cfg.cbndx;
+	int i;

+	actlrvar = qsmmu->data->actlrvar;
+
+	if (!actlrvar)
+		goto end;
+
+	for (i = 0; i < qsmmu->data->num_smmu ; i++) {
+		if (actlrvar[i].io_start == smmu->ioaddr) {
+			qcom_smmu_set_actlr(dev, smmu, cbndx,
+						actlrvar[i].actlrcfg);
+			break;
 		}
 	}

+end:
 	smmu_domain->cfg.flush_walk_prefer_tlbiasid = true;

 	return 0;

Thanks & regards,
Bibek

> Konrad