| Message ID | 467590c40029ef0712b1fd38f2928fd4f08d09af.1726232138.git.robin.murphy@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | iommu/arm-smmu: Clarify MMU-500 CPRE workaround | expand |
On 2024-09-13 1:55 pm, Robin Murphy wrote: > CPRE workarounds are implicated in at least 5 MMU-500 errata, some of > which remain unfixed. The comment and warning message have proven to be > unhelpfully misleading about this scope, so reword them to get the point > across with less risk of going out of date or confusing users. > > Signed-off-by: Robin Murphy <robin.murphy@arm.com> > --- > drivers/iommu/arm/arm-smmu/arm-smmu-impl.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c b/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c > index 9dc772f2cbb2..2edb1c1658ad 100644 > --- a/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c > +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c > @@ -130,7 +130,7 @@ int arm_mmu500_reset(struct arm_smmu_device *smmu) > > /* > * Disable MMU-500's not-particularly-beneficial next-page > - * prefetcher for the sake of errata #841119 and #826419. > + * prefetcher for the sake of at least 5 known errata. > */ > for (i = 0; i < smmu->num_context_banks; ++i) { > reg = arm_smmu_cb_read(smmu, i, ARM_SMMU_CB_ACTLR); > @@ -138,7 +138,7 @@ int arm_mmu500_reset(struct arm_smmu_device *smmu) > arm_smmu_cb_write(smmu, i, ARM_SMMU_CB_ACTLR, reg); > reg = arm_smmu_cb_read(smmu, i, ARM_SMMU_CB_ACTLR); > if (reg & ARM_MMU500_ACTLR_CPRE) > - dev_warn_once(smmu->dev, "Failed to disable prefetcher [errata #841119 and #826419], check ACR.CACHE_LOCK\n"); > + dev_warn_once(smmu->dev, "Failed to disable prefetcher for errata workarounds, check ACR.CACHE_LOCK\n"); Come to think of it, this should probably also refer to SACR rather than ACR, given that we already *have* attempted to program the Non-Secure side... Robin. > } > > return 0;
On Fri, Sep 13, 2024 at 04:13:29PM +0100, Robin Murphy wrote: > On 2024-09-13 1:55 pm, Robin Murphy wrote: > > CPRE workarounds are implicated in at least 5 MMU-500 errata, some of > > which remain unfixed. The comment and warning message have proven to be > > unhelpfully misleading about this scope, so reword them to get the point > > across with less risk of going out of date or confusing users. > > > > Signed-off-by: Robin Murphy <robin.murphy@arm.com> > > --- > > drivers/iommu/arm/arm-smmu/arm-smmu-impl.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c b/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c > > index 9dc772f2cbb2..2edb1c1658ad 100644 > > --- a/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c > > +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c > > @@ -130,7 +130,7 @@ int arm_mmu500_reset(struct arm_smmu_device *smmu) > > /* > > * Disable MMU-500's not-particularly-beneficial next-page > > - * prefetcher for the sake of errata #841119 and #826419. > > + * prefetcher for the sake of at least 5 known errata. > > */ > > for (i = 0; i < smmu->num_context_banks; ++i) { > > reg = arm_smmu_cb_read(smmu, i, ARM_SMMU_CB_ACTLR); > > @@ -138,7 +138,7 @@ int arm_mmu500_reset(struct arm_smmu_device *smmu) > > arm_smmu_cb_write(smmu, i, ARM_SMMU_CB_ACTLR, reg); > > reg = arm_smmu_cb_read(smmu, i, ARM_SMMU_CB_ACTLR); > > if (reg & ARM_MMU500_ACTLR_CPRE) > > - dev_warn_once(smmu->dev, "Failed to disable prefetcher [errata #841119 and #826419], check ACR.CACHE_LOCK\n"); > > + dev_warn_once(smmu->dev, "Failed to disable prefetcher for errata workarounds, check ACR.CACHE_LOCK\n"); > > Come to think of it, this should probably also refer to SACR rather than > ACR, given that we already *have* attempted to program the Non-Secure > side... I'm happy to pick up a v2 with that change. Cheers, Will
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c b/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c index 9dc772f2cbb2..2edb1c1658ad 100644 --- a/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-impl.c @@ -130,7 +130,7 @@ int arm_mmu500_reset(struct arm_smmu_device *smmu) /* * Disable MMU-500's not-particularly-beneficial next-page - * prefetcher for the sake of errata #841119 and #826419. + * prefetcher for the sake of at least 5 known errata. */ for (i = 0; i < smmu->num_context_banks; ++i) { reg = arm_smmu_cb_read(smmu, i, ARM_SMMU_CB_ACTLR); @@ -138,7 +138,7 @@ int arm_mmu500_reset(struct arm_smmu_device *smmu) arm_smmu_cb_write(smmu, i, ARM_SMMU_CB_ACTLR, reg); reg = arm_smmu_cb_read(smmu, i, ARM_SMMU_CB_ACTLR); if (reg & ARM_MMU500_ACTLR_CPRE) - dev_warn_once(smmu->dev, "Failed to disable prefetcher [errata #841119 and #826419], check ACR.CACHE_LOCK\n"); + dev_warn_once(smmu->dev, "Failed to disable prefetcher for errata workarounds, check ACR.CACHE_LOCK\n"); } return 0;
CPRE workarounds are implicated in at least 5 MMU-500 errata, some of which remain unfixed. The comment and warning message have proven to be unhelpfully misleading about this scope, so reword them to get the point across with less risk of going out of date or confusing users. Signed-off-by: Robin Murphy <robin.murphy@arm.com> --- drivers/iommu/arm/arm-smmu/arm-smmu-impl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)