[PATCH v4] ata: pata_of_platform: Use platform_get_irq_optional() to get the interrupt

[PATCH v4] ata: pata_of_platform: Use platform_get_irq_optional() to get the interrupt

[Lad Prabhakar]

platform_get_resource(pdev, IORESOURCE_IRQ, ..) relies on static
allocation of IRQ resources in DT core code, this causes an issue
when using hierarchical interrupt domains using "interrupts" property
in the node as this bypasses the hierarchical setup and messes up the
irq chaining.

In preparation for removal of static setup of IRQ resource from DT core
code use platform_get_irq_optional().

Note this code just sets the start and not the end of IRQ resource as
__pata_platform_probe() only uses the start member and also we don't
set the IRQ resource flags as this is handled automatically for DT.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
---
Hi All,

This patch is part of series [1]. I'll re-visit merging of pata_of_platform
into pata_platform at later point. As my primary focus is removal of static
setup of IRQ resource from DT core code.

[1] https://patchwork.ozlabs.org/project/linux-ide/list/?series=278349

Cheers,
Prabhakar
---
 drivers/ata/pata_of_platform.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/ata/pata_of_platform.c b/drivers/ata/pata_of_platform.c
index 35aa158fc976..f2e012bc24e8 100644
--- a/drivers/ata/pata_of_platform.c
+++ b/drivers/ata/pata_of_platform.c
@@ -25,11 +25,12 @@ static int pata_of_platform_probe(struct platform_device *ofdev)
 	struct device_node *dn = ofdev->dev.of_node;
 	struct resource io_res;
 	struct resource ctl_res;
-	struct resource *irq_res;
+	struct resource irq_res;
 	unsigned int reg_shift = 0;
 	int pio_mode = 0;
 	int pio_mask;
 	bool use16bit;
+	int irq;
 
 	ret = of_address_to_resource(dn, 0, &io_res);
 	if (ret) {
@@ -45,7 +46,14 @@ static int pata_of_platform_probe(struct platform_device *ofdev)
 		return -EINVAL;
 	}
 
-	irq_res = platform_get_resource(ofdev, IORESOURCE_IRQ, 0);
+	irq = platform_get_irq_optional(ofdev, 0);
+	if (irq < 0 && irq != -ENXIO)
+		return irq;
+
+	if (irq > 0) {
+		memset(&irq_res, 0, sizeof(irq_res));
+		irq_res.start = irq;
+	}
 
 	of_property_read_u32(dn, "reg-shift", &reg_shift);
 
@@ -63,7 +71,7 @@ static int pata_of_platform_probe(struct platform_device *ofdev)
 	pio_mask = 1 << pio_mode;
 	pio_mask |= (1 << pio_mode) - 1;
 
-	return __pata_platform_probe(&ofdev->dev, &io_res, &ctl_res, irq_res,
+	return __pata_platform_probe(&ofdev->dev, &io_res, &ctl_res, irq > 0 ? &irq_res : NULL,
 				     reg_shift, pio_mask, &pata_platform_sht,
 				     use16bit);
 }
-- 
2.17.1

Re: [PATCH v4] ata: pata_of_platform: Use platform_get_irq_optional() to get the interrupt

[Andy Shevchenko]

On Wed, Jan 5, 2022 at 2:14 AM Lad Prabhakar
<prabhakar.mahadev-lad.rj@bp.renesas.com> wrote:
>
> platform_get_resource(pdev, IORESOURCE_IRQ, ..) relies on static
> allocation of IRQ resources in DT core code, this causes an issue
> when using hierarchical interrupt domains using "interrupts" property
> in the node as this bypasses the hierarchical setup and messes up the
> irq chaining.
>
> In preparation for removal of static setup of IRQ resource from DT core
> code use platform_get_irq_optional().
>
> Note this code just sets the start and not the end of IRQ resource as
> __pata_platform_probe() only uses the start member and also we don't
> set the IRQ resource flags as this is handled automatically for DT.

...

> +       irq = platform_get_irq_optional(ofdev, 0);
> +       if (irq < 0 && irq != -ENXIO)
> +               return irq;
> +
> +       if (irq > 0) {

> +               memset(&irq_res, 0, sizeof(irq_res));

To avoid subtle mistakes in the future, I would suggest doing this
unconditionally.

> +               irq_res.start = irq;

This is interesting. For consistency I would assign the end as well.

> +       }

Hence something like

memset(&irq_res, ...);

irq = ...
if (irq < 0 ...)
  return irq;
if (irq > 0) {
  irq_res.start = irq;
  irq_res.end = irq;
}

-- 
With Best Regards,
Andy Shevchenko