Re: [PATCH v2 01/13] iommu/rockchip: Request irqs in rk_iommu_probe()

Robin Murphy
2018-01-17T12:18:21Z

On 16/01/18 13:25, Jeffy Chen wrote:
> Suggested-by: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>
> Signed-off-by: Jeffy Chen <jeffy.chen-TNX95d0MmH7DzftRWevZcw@public.gmane.org>
> ---
>
> Changes in v2: None
>
> drivers/iommu/rockchip-iommu.c | 38 +++++++++++---------------------------
> 1 file changed, 11 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
> index 9d991c2d8767..4a12d4746095 100644
> --- a/drivers/iommu/rockchip-iommu.c
> +++ b/drivers/iommu/rockchip-iommu.c
> @@ -18,6 +18,7 @@
> #include <linux/mm.h>
> #include <linux/module.h>
> #include <linux/of.h>
> +#include <linux/of_irq.h>
> #include <linux/of_platform.h>
> #include <linux/platform_device.h>
> #include <linux/slab.h>
> @@ -91,7 +92,6 @@ struct rk_iommu {
> void __iomem **bases;
> int num_mmu;
> int *irq;

Nit: irq seems to be redundant now as well.

> - int num_irq;
> bool reset_disabled;
> struct iommu_device iommu;
> struct list_head node; /* entry in rk_iommu_domain.iommus */
> @@ -830,13 +830,6 @@ static int rk_iommu_attach_device(struct iommu_domain *domain,
>
> iommu->domain = domain;
>
> - for (i = 0; i < iommu->num_irq; i++) {
> - ret = devm_request_irq(iommu->dev, iommu->irq[i], rk_iommu_irq,
> - IRQF_SHARED, dev_name(dev), iommu);
> - if (ret)
> - return ret;
> - }
> -
> for (i = 0; i < iommu->num_mmu; i++) {
> rk_iommu_write(iommu->bases[i], RK_MMU_DTE_ADDR,
> rk_domain->dt_dma);
> @@ -885,9 +878,6 @@ static void rk_iommu_detach_device(struct iommu_domain *domain,
> }
> rk_iommu_disable_stall(iommu);
>
> - for (i = 0; i < iommu->num_irq; i++)
> - devm_free_irq(iommu->dev, iommu->irq[i], iommu);
> -
> iommu->domain = NULL;
>
> dev_dbg(dev, "Detached from iommu domain\n");
> @@ -1138,7 +1128,7 @@ static int rk_iommu_probe(struct platform_device *pdev)
> struct rk_iommu *iommu;
> struct resource *res;
> int num_res = pdev->num_resources;
> - int err, i;
> + int err, i, irq, num_irq;
>
> iommu = devm_kzalloc(dev, sizeof(*iommu), GFP_KERNEL);
> if (!iommu)
> @@ -1165,23 +1155,17 @@ static int rk_iommu_probe(struct platform_device *pdev)
> if (iommu->num_mmu == 0)
> return PTR_ERR(iommu->bases[0]);
>
> - iommu->num_irq = platform_irq_count(pdev);
> - if (iommu->num_irq < 0)
> - return iommu->num_irq;
> - if (iommu->num_irq == 0)
> - return -ENXIO;
> -
> - iommu->irq = devm_kcalloc(dev, iommu->num_irq, sizeof(*iommu->irq),
> - GFP_KERNEL);
> - if (!iommu->irq)
> - return -ENOMEM;
> -
> - for (i = 0; i < iommu->num_irq; i++) {
> - iommu->irq[i] = platform_get_irq(pdev, i);
> - if (iommu->irq[i] < 0) {
> - dev_err(dev, "Failed to get IRQ, %d\n", iommu->irq[i]);
> + num_irq = of_irq_count(dev->of_node);

To follow up on the other reply, I'm not sure you really need to count
the IRQs beforehand at all - you're going to be looping through
platform_get_irq() and handling errors anyway, so you may as well just
start at 0 and keep going until -ENOENT (or use platform_get_resource()
to double-check whether an index should be valid, as we do in arm_smmu).

Otherwise, it looks like everything that the IRQ handler needs in the
iommu struct (dev, num_mmu and bases) is already initialised by this
point, so we should be OK with respect to races.

Robin.

> + for (i = 0; i < num_irq; i++) {
> + irq = platform_get_irq(pdev, i);
> + if (irq < 0) {
> + dev_err(dev, "Failed to get IRQ, %d\n", irq);
> return -ENXIO;
> }
> + err = devm_request_irq(iommu->dev, irq, rk_iommu_irq,
> + IRQF_SHARED, dev_name(dev), iommu);
> + if (err)
> + return err;
> }
>
> iommu->reset_disabled = device_property_read_bool(dev,
>