Re: [PATCH v3 6/7] iommu/arm-smmu-v3: Add workaround for Cavium ThunderX2 erratum #126

[Geetha Akula]

On Mon, May 8, 2017 at 4:51 PM, Robin Murphy <robin.murphy@xxxxxxx> wrote:
> On 05/05/17 13:08, Geetha sowjanya wrote:
>> From: Geetha Sowjanya <geethasowjanya.akula@xxxxxxxxxx>
>>
>> Cavium ThunderX2 SMMU doesn't support MSI and also doesn't have unique irq
>> lines for gerror, eventq and cmdq-sync.
>>
>> This patch addresses the issue by checking if any interrupt sources are
>> using same irq number, then they are registered as shared irqs.
>>
>> Signed-off-by: Geetha Sowjanya <geethasowjanya.akula@xxxxxxxxxx>
>> ---
>>  drivers/iommu/arm-smmu-v3.c | 32 ++++++++++++++++++++++++++++----
>>  1 file changed, 28 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
>> index 016b702..46428e7 100644
>> --- a/drivers/iommu/arm-smmu-v3.c
>> +++ b/drivers/iommu/arm-smmu-v3.c
>> @@ -2236,10 +2236,30 @@ static void arm_smmu_setup_msis(struct arm_smmu_device *smmu)
>>       devm_add_action(dev, arm_smmu_free_msis, dev);
>>  }
>>
>> +static int get_irq_flags(struct arm_smmu_device *smmu, int irq)
>> +{
>> +     int match_count = 0;
>> +
>> +     if (irq == smmu->evtq.q.irq)
>> +             match_count++;
>> +     if (irq == smmu->cmdq.q.irq)
>> +             match_count++;
>> +     if (irq == smmu->gerr_irq)
>> +             match_count++;
>> +     if (irq == smmu->priq.q.irq)
>> +             match_count++;
>> +
>> +     if (match_count > 1)
>> +             return IRQF_SHARED | IRQF_ONESHOT;
>> +
>> +     return 0;
>
> I'd say just have this return IRQF_ONESHOT in the non-shared case...
>
>> +}
>> +
>>  static int arm_smmu_setup_irqs(struct arm_smmu_device *smmu)
>>  {
>>       int ret, irq;
>>       u32 irqen_flags = IRQ_CTRL_EVTQ_IRQEN | IRQ_CTRL_GERROR_IRQEN;
>> +     u32 irqflags = 0;
>>
>>       /* Disable IRQs first */
>>       ret = arm_smmu_write_reg_sync(smmu, 0, ARM_SMMU_IRQ_CTRL,
>> @@ -2254,9 +2274,10 @@ static int arm_smmu_setup_irqs(struct arm_smmu_device *smmu)
>>       /* Request interrupt lines */
>>       irq = smmu->evtq.q.irq;
>>       if (irq) {
>> +             irqflags = get_irq_flags(smmu, irq);
>>               ret = devm_request_threaded_irq(smmu->dev, irq, NULL,
>>                                               arm_smmu_evtq_thread,
>> -                                             IRQF_ONESHOT,
>> +                                             IRQF_ONESHOT | irqflags,
>
> ...and pass get_irq_flags(smmu, irq) directly as the argument here.
>
> The local variable and intermediate logic only seem to add unnecessary
> complexity, given that the two cases we actually end up with are:
>
> IRQF_ONESHOT | 0
>
> vs.
>
> IRQF_ONESHOT | IRQF_SHARED | IRQF_ONESHOT
>
> neither of which looks particularly sensible.
>
> Robin.
>
I will resubmit the patch with suggested changes.

Thank you,
Geetha.



>>                                               "arm-smmu-v3-evtq", smmu);
>>               if (ret < 0)
>>                       dev_warn(smmu->dev, "failed to enable evtq irq\n");
>> @@ -2264,8 +2285,9 @@ static int arm_smmu_setup_irqs(struct arm_smmu_device *smmu)
>>
>>       irq = smmu->cmdq.q.irq;
>>       if (irq) {
>> +             irqflags = get_irq_flags(smmu, irq);
>>               ret = devm_request_irq(smmu->dev, irq,
>> -                                    arm_smmu_cmdq_sync_handler, 0,
>> +                                    arm_smmu_cmdq_sync_handler, irqflags,
>>                                      "arm-smmu-v3-cmdq-sync", smmu);
>>               if (ret < 0)
>>                       dev_warn(smmu->dev, "failed to enable cmdq-sync irq\n");
>> @@ -2273,8 +2295,9 @@ static int arm_smmu_setup_irqs(struct arm_smmu_device *smmu)
>>
>>       irq = smmu->gerr_irq;
>>       if (irq) {
>> +             irqflags = get_irq_flags(smmu, irq);
>>               ret = devm_request_irq(smmu->dev, irq, arm_smmu_gerror_handler,
>> -                                    0, "arm-smmu-v3-gerror", smmu);
>> +                                    irqflags, "arm-smmu-v3-gerror", smmu);
>>               if (ret < 0)
>>                       dev_warn(smmu->dev, "failed to enable gerror irq\n");
>>       }
>> @@ -2282,9 +2305,10 @@ static int arm_smmu_setup_irqs(struct arm_smmu_device *smmu)
>>       if (smmu->features & ARM_SMMU_FEAT_PRI) {
>>               irq = smmu->priq.q.irq;
>>               if (irq) {
>> +                     irqflags = get_irq_flags(smmu, irq);
>>                       ret = devm_request_threaded_irq(smmu->dev, irq, NULL,
>>                                                       arm_smmu_priq_thread,
>> -                                                     IRQF_ONESHOT,
>> +                                                     IRQF_ONESHOT | irqflags,
>>                                                       "arm-smmu-v3-priq",
>>                                                       smmu);
>>                       if (ret < 0)
>>
>