Messages in this thread | | | Subject | Re: [PATCH 4/5] iommu/arm-smmu: Make way to add Qcom's smmu-500 errata handling | From | Vivek Gautam <> | Date | Tue, 28 Aug 2018 12:29:02 +0530 |
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Hi Robin,
On 8/14/2018 10:29 PM, Robin Murphy wrote: > On 14/08/18 11:55, Vivek Gautam wrote: >> Cleanup to re-use some of the stuff >> >> Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org> >> --- >> drivers/iommu/arm-smmu.c | 32 +++++++++++++++++++++++++------- >> 1 file changed, 25 insertions(+), 7 deletions(-) > > I think the overall diffstat would be an awful lot smaller if the > erratum workaround just has its own readl_poll_timeout() as it does in > the vendor kernel. The burst-polling loop is for minimising latency in > high-throughput situations, and if you're in a workaround which has to > lock *every* register write and issue two firmware calls around each > sync I think you're already well out of that game.
Sorry for the delayed response. I was on vacation. I will fix this in my next version by adding the separate read_poll_timeout() for the erratum WA.
> >> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c >> index 32e86df80428..75c146751c87 100644 >> --- a/drivers/iommu/arm-smmu.c >> +++ b/drivers/iommu/arm-smmu.c >> @@ -391,21 +391,31 @@ static void __arm_smmu_free_bitmap(unsigned >> long *map, int idx) >> clear_bit(idx, map); >> } >> -/* Wait for any pending TLB invalidations to complete */ >> -static void __arm_smmu_tlb_sync(struct arm_smmu_device *smmu, >> - void __iomem *sync, void __iomem *status) >> +static int __arm_smmu_tlb_sync_wait(void __iomem *status) >> { >> unsigned int spin_cnt, delay; >> - writel_relaxed(0, sync); >> for (delay = 1; delay < TLB_LOOP_TIMEOUT; delay *= 2) { >> for (spin_cnt = TLB_SPIN_COUNT; spin_cnt > 0; spin_cnt--) { >> if (!(readl_relaxed(status) & sTLBGSTATUS_GSACTIVE)) >> - return; >> + return 0; >> cpu_relax(); >> } >> udelay(delay); >> } >> + >> + return -EBUSY; >> +} >> + >> +/* Wait for any pending TLB invalidations to complete */ >> +static void __arm_smmu_tlb_sync(struct arm_smmu_device *smmu, >> + void __iomem *sync, void __iomem *status) >> +{ >> + writel_relaxed(0, sync); >> + >> + if (!__arm_smmu_tlb_sync_wait(status)) >> + return; >> + >> dev_err_ratelimited(smmu->dev, >> "TLB sync timed out -- SMMU may be deadlocked\n"); >> } >> @@ -461,8 +471,9 @@ static void arm_smmu_tlb_inv_context_s2(void >> *cookie) >> arm_smmu_tlb_sync_global(smmu); >> } >> -static void arm_smmu_tlb_inv_range_nosync(unsigned long iova, >> size_t size, >> - size_t granule, bool leaf, void *cookie) >> +static void __arm_smmu_tlb_inv_range_nosync(unsigned long iova, >> size_t size, >> + size_t granule, bool leaf, >> + void *cookie) >> { >> struct arm_smmu_domain *smmu_domain = cookie; >> struct arm_smmu_cfg *cfg = &smmu_domain->cfg; >> @@ -498,6 +509,13 @@ static void >> arm_smmu_tlb_inv_range_nosync(unsigned long iova, size_t size, >> } >> } >> +static void arm_smmu_tlb_inv_range_nosync(unsigned long iova, >> size_t size, >> + size_t granule, bool leaf, >> + void *cookie) >> +{ >> + __arm_smmu_tlb_inv_range_nosync(iova, size, granule, leaf, cookie); >> +} >> + > > AFAICS even after patch #5 this does absolutely nothing except make > the code needlessly harder to read :(
Sure, I will rather call arm_smmu_tlb_inv_range_nosync() from qcom_errata_tlb_inv_range_nosync() then make this change. Thanks for the review.
Best regards Vivek
> > Robin. > >> /* >> * On MMU-401 at least, the cost of firing off multiple TLBIVMIDs >> appears >> * almost negligible, but the benefit of getting the first one in >> as far ahead >>
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