Re: RT and omap-gpio irqchip with DeviceTree

[Torben Hohn <torbenh@linutronix.de>]

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On Tue, Jul 02, 2013 at 02:15:46PM +0200, Javier Martinez Canillas wrote:
> + Grant, Linus W and Jean-Christophe.
> 
> On Tue, Jul 2, 2013 at 1:44 PM, Torben Hohn <torbenh@linutronix.de> wrote:
> >
> > Hi..
> >
> > I am running into Problems with a network adapter IRQ connected to an
> > omap-gpio pin.
> >
> > omap-gpio expects gpio-request() to be called before i can use the pin.
> > But this is abstracted via the DeviceTree bindings.
> >
> > I see 8d4c277e185c31359cf70573d8b0351fb7dd0dfe in mainline.
> > This one just puts a warning into the exact place, i am dealing with.
> > But i need to make this work, instead of bailing out.
> >
> 
> This has been discussed extensively on the linux-omap mailing list and
> the agreement is that it has to be handled by the IRQ core. So when a
> GPIO line is mapped in the IRQ domain with irq_create_of_mapping(),
> the core has to take care to request the GPIO and configure it as
> input.

Can you give me a pointer to this discussion please ?
Because i fail to understand why you just dont save the irq_type in some
private data structure, and then use chip->irq_enable() or something.


> 
>  But until we have this general solution we have to do it on a per irq
> chip driver basis and the less hack-ish solution is to have a custom
> .map function handler that request the GPIO used as IRQ.
> 
> There is already a patch [1] queued in Linus Walleij linux-gpio tree
> [2] for-next branch that implements this for OMAP GPIO. It would be
> great if you can test it and give feedback.

Thanks for the pointer.
The kernel i am working on is based on 3.8.x (this is before the
irq_domain change to linear)

First i only backported: [1] and [2]

With these i see big streams like these:
[    1.554809] omap_gpio gpio.9: Could not request GPIO-256
[    1.560394] omap_gpio gpio.9: Could not request GPIO-255
[    1.566009] omap_gpio gpio.9: Could not request GPIO-254
[    1.571594] omap_gpio gpio.9: Could not request GPIO-253
[    1.577178] omap_gpio gpio.9: Could not request GPIO-252
[    1.582794] omap_gpio gpio.9: Could not request GPIO-251

This is basically coming from irq_domain_add_legacy() which calls
ops->map(domain, irq, hwirq) before the gpio chip is actually added.

I fixed it by also taking [3].

However, OMAP1 is still calling irq_domain_add_legacy(). This would
probably break with DeviceTree. 
But since omap1 doesnt use DeviceTree, this is probably a non-issue.

[1] https://git.kernel.org/cgit/linux/kernel/git/linusw/linux-gpio.git/commit/?h=for-next&id=570c4bb53366157fa076922d0fc7e7adfd81cf42
[2] https://git.kernel.org/cgit/linux/kernel/git/linusw/linux-gpio.git/commit/?h=for-next&id=50fc1d067d9f4b6c99717b91c1aaaa618075f859
[3] https://git.kernel.org/cgit/linux/kernel/git/linusw/linux-gpio.git/commit/?h=for-next&id=ede4d7a5b9835510fd1f724367f68d2fa4128453


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Mit freundlichen Grüßen
Torben Hohn

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