Re: [RFC PATCH 1/5] iommu/arm-smmu-v3: Refactor arm_smmu_setup_irqs

[Nicolin Chen <nicolinc@nvidia.com>]

On Wed, Mar 19, 2025 at 12:42:50AM +0000, Pranjal Shrivastava wrote:
> Refactor arm_smmu_setup_irqs by splitting it into two parts, one for
> registering interrupt handlers and the other one for enabling interrupt
> generation in the hardware. This refactor helps in re-initialization of
> hardware interrupts as part of a subsequent patch that enables runtime
> power management for the arm-smmu-v3 driver.
> 
> Signed-off-by: Pranjal Shrivastava <praan@google.com>
> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 50 ++++++++++++++++-----
>  1 file changed, 38 insertions(+), 12 deletions(-)

> +static int arm_smmu_setup_irqs(struct arm_smmu_device *smmu)
> +{
> +	int ret, irq;
> +
> +	/* Disable IRQs first */
> +	ret = arm_smmu_disable_irqs(smmu);

Why do we need to touch HW in this SW handler setting-up function?

> @@ -4171,6 +4187,9 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu)
>  		return ret;
>  	}
>  
> +	/* Enable interrupt generation on the SMMU */
> +	arm_smmu_enable_irqs(smmu);
> +

Should this replace arm_smmu_setup_irqs() in this function? I see
arm_smmu_setup_irqs() still remain in arm_smmu_device_reset(), so
a normal probe routine would call it twice?

In my view, arm_smmu_setup_irqs() can be done just once, moving
out of arm_smmu_device_reset() and up to arm_smmu_device_probe()?

Thanks
Nicolin