Re: [PATCH] Revert "smc91x: retrieve IRQ and trigger flags in a modern way"

From: Linus Walleij
Date: Thu Feb 12 2015 - 21:16:26 EST

On Fri, Feb 13, 2015 at 12:59 AM, Robert Jarzmik <robert.jarzmik@xxxxxxx> wrote:

> The commit breaks the legacy platforms, ie. these not using device-tree,
> and setting up the interrupt resources with a flag to activate edge
> detection. The issue was found on the zylonite platform.
> The reason is that zylonite uses platform resources to pass the interrupt number
> and the irq flags (here IORESOURCE_IRQ_HIGHEDGE). It expects the driver to
> request the irq with these flags, which in turn setups the irq as high edge
> triggered.
> After the patch, this was supposed to be taken care of with :
> irq_resflags = irqd_get_trigger_type(irq_get_irq_data(ndev->irq));
> But irq_resflags is 0 for legacy platforms, while for example in
> arch/arm/mach-pxa/zylonite.c, in struct resource smc91x_resources[] the
> irq flag is specified. This breaks zylonite because the interrupt is not
> setup as triggered, and hardware doesn't provide interrupts.
> Signed-off-by: Robert Jarzmik <robert.jarzmik@xxxxxxx>

But isn't the real problem that in the device tree case,
irq_get_irq_data(ndev->irq) will work becaus parsing an interrupt
from the device tree populates it correctly in platform_get_irq()
whereas for the legacy lookup it just fetches the number.

So to me it seems like a weakness in the platform_get_irq()
helper altogether.

Does the following work? (I can send as a separate patch for
testing if you like).

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 9421fed40905..301f4b9ae908 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -101,6 +101,15 @@ int platform_get_irq(struct platform_device *dev,
unsigned int num)

r = platform_get_resource(dev, IORESOURCE_IRQ, num);
+ /*
+ * The resources may pass trigger flags to the irqs that need
+ * to be set up. It so happens that the trigger flags for
+ * IORESOURCE_BITS correspond 1-to-1 to the IRQF_TRIGGER*
+ * settings.
+ */
+ if (r->flags & IORESOURCE_BITS)
+ irqd_set_trigger_type(irq_get_irq_data(r->start),
+ r->flags & IORESOURCE_BITS);

Linus Walleij
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