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SubjectRe: [PATCH v3 6/7] iommu/arm-smmu-v3: Add workaround for Cavium ThunderX2 erratum #126
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On 05/05/17 13:08, Geetha sowjanya wrote:
> From: Geetha Sowjanya <geethasowjanya.akula@cavium.com>
>
> 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@cavium.com>
> ---
> 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.

> "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)
>

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