Hi Linus,
On Mon, Feb 15, 2016 at 11:10 PM, Linus Walleij
<linus.walleij@xxxxxxxxxx> wrote:
> On Tue, Feb 9, 2016 at 4:19 PM, Geert Uytterhoeven
> <geert+renesas@xxxxxxxxx> wrote:
>
> Quoting in verbatim as we add new recipients.
>
> I don't know about any runtime_pm_get():s from the irqchip functions:
> Ulf and others are discussing with Thomas Gleixner about a more general
> solution here.
>
> But since it's a regression I guess we need quick decisions.
>
>> The R-Car GPIO driver handles Runtime PM for requested GPIOs only.
>>
>> When using a GPIO purely as an interrupt source, no Runtime PM handling
>> is done, and the GPIO module's clock may not be enabled.
>>
>> To fix this:
>> - Add .irq_request_resources() and .irq_release_resources() callbacks
>> to handle Runtime PM when an interrupt is requested,
>
> This is pretty OK since they are slowpath.
>
>> - Runtime-resume the device before writing to the GPIO module's
>> registers for disabling/enabling an interrupt, or for configuring
>> the interrupt type,
>
> Will that have *any* effect now that .irq_request_resources has increased
> usecount to 1?
>
> Isn't it enough with the patches to .irq_request/release_resources to get
> this working?
The registers are also being written to to:
1. Disable the IRQ,
2. Set the type.
Unfortunately .irq_request() is the third step, not the first.
>> - Add checks to warn when the GPIO module's registers are accessed
>> while the device is runtime-suspended.
>>
>> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
>> ---
>> This fixes ravb Ethernet on r8a7795/Salvator-X, which was "broken" by
>> commit d5c3d84657db57bd ("net: phy: Avoid polling PHY with
>> PHY_IGNORE_INTERRUPTS").
>>
>> Does it also fix the HDMI interrupt on r8a7791/Koelsch?
>>
>> Notes:
>> 1. I assume gpio_rcar_irq_{dis,en}able() may be called from contexts
>> where pm_runtime_get_sync() may not be called.
>> However, so far I didn't see any reports from the might_sleep_if()
>> check in __pm_runtime_resume(),
>> 2. gpio_rcar_irq_disable() is called from the IRQ core before
>> gpio_rcar_irq_set_type().
>> Else an alternative solution could be to just runtime-resume the
>> device from gpio_rcar_irq_set_type() when an interrupt is setup,
>> and never call pm_runtime_put() again. That would cause issues when
>> compiling gpio-rcar as a module, though.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
