On 09/12/2017 07:03 AM, Linus Walleij wrote:
On Thu, Sep 7, 2017 at 1:42 PM, Masahiro Yamada
<yamada.masahiro@xxxxxxxxxxxxx> wrote:
This GPIO controller device is used on UniPhier SoCs.
It also serves as an interrupt controller, but interrupt signals are
just delivered to the parent irqchip without any latching or OR'ing.
This is implemented by using hierarchy IRQ domain.
Implementation note:
Unfortunately, the IRQ mapping from this controller to the parent is
random. (48, 49, ..., 63, 154, 155, ...)
If "interrupts" property is used, IRQ resources may be statically
allocated when platform devices are populated from DT. This can be
a problem for the hierarchy IRQ domain because IRQ allocation must
happen from the outer-most domain up to the root domain in order to
build up the stacked IRQ. (https://lkml.org/lkml/2017/7/6/758)
Solutions to work around it could be to hard-code parent hwirqs or
to invent a driver-specific DT property.
Here, the new API irq_domain_push_irq() was merged by v4.14-rc1.
It allows to add irq_data to the existing hierarchy. It will help
to make this driver work whether the parent has already initialized
the hierarchy or not.
Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
---
Changes in v4:
- Add COMPILE_TEST and select IRQ_DOMAIN_HIERARCHY
- Reimplement irqchip part by using irq_domain_push_irq()
Awesome improvement. There was a build error and I also
would like David Daney to have a look at this so we know we
use things the right way,
It looks correct to me.
I haven't verified it, but I think the OF device-tree probing code for
the platform devices will automatically xlat-and-map all those irqs, so
that the irq_domain_push_irq() is required to get the domain hierarchy
properly configured. It would be similar to the PCI case where we
configure all the MSI-X and then do the irq_domain_push_irq() in the
Cavium ThunderX driver.
If interrupt handling has been verified to work with this driver, I
would say that we are probably using things "the right way".
David.
but overall I am happy after this
so I hope I will be able to apply next version.
Yours,
Linus Walleij
--
To unsubscribe from this list: send the line "unsubscribe linux-gpio" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
