Re: [PATCH] drivers: platform: parse IRQ flags from resources

[Robert Jarzmik <robert.jarzmik@free.fr>]

Linus Walleij <linus.walleij@linaro.org> writes:

> On Fri, Feb 20, 2015 at 4:40 PM, Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
>> On Wed, Feb 18, 2015 at 05:12:18PM +0100, Linus Walleij wrote:
>>> This fixes a regression from the net subsystem:
>>> After commit d52fdbb735c36a209f36a628d40ca9185b349ba7
>>> "smc91x: retrieve IRQ and trigger flags in a modern way"
>>> a regression would appear on some legacy platforms such
>>> as the ARM PXA Zylonite that specify IRQ resources like
>>> this:
>>>
>>> static struct resource r = {
>>>        .start  = X,
>>>        .end    = X,
>>>        .flags  = IORESOURCE_IRQ | IORESOURCE_IRQ_HIGHEDGE,
>>> };
>>>
>>> The previous code would retrieve the resource and parse
>>> the high edge setting in the SMC91x driver, a use pattern
>>> that means every driver specifying an IRQ flag from a
>>> static resource need to parse resource flags and apply
>>> them at runtime.
>>>
>>> As we switched the code to use IRQ descriptors to retrieve
>>> the the trigger type like this:
>>>
>>>   irqd_get_trigger_type(irq_get_irq_data(...));
>>>
>>> the code would work for new platforms using e.g. device
>>> tree as the backing irq descriptor would have its flags
>>> properly set, whereas this kind of oldstyle static
>>> resources at no point assign the trigger flags to the
>>> corresponding IRQ descriptor.
>>>
>>> To make the behaviour identical on modern device tree
>>> and legacy static platform data platforms, modify
>>> platform_get_irq() to assign the trigger flags to the
>>> irq descriptor when a client looks up an IRQ from static
>>> resources.
>>>
>>> Fixes: d52fdbb735c3 ("smc91x: retrieve IRQ and trigger flags in a modern way")
>>> Tested-by: Robert Jarzmik <robert.jarzmik@free.fr>
>>> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
>>> ---
>>> Greg/Grant: I'm a bit uncertain here. It's kind of
>>> unintuitive that the platform_get_irq() function go around
>>> setting trigger flags on IRQ descriptors, but it is *also*
>>> unintuitive that the descriptor has all the right flags
>>> from a device tree but not from an identical static
>>> resource. And it is bloated to have resource parsing in
>>> each and every driver. The alternative is to revert
>>> the offending patch and live with some resource parsing
>>> all over the place. (Such a patch is posted.)
>>> ---
>>>  drivers/base/platform.c | 9 +++++++++
>>>  1 file changed, 9 insertions(+)
>>>
>>> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
>>> index 9421fed40905..e68ab79df28b 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 && r->flags & IORESOURCE_BITS)
>>> +             irqd_set_trigger_type(irq_get_irq_data(r->start),
>>> +                                   r->flags & IORESOURCE_BITS);
>>
>> Ah, found this now.
>>
>> I'll defer to Grant as to what to do here, as I have no idea...
>
> OK no answer, Greg can you just merge this patch then, because
> I say it's my best bet for a solution.

Hi Linus, Greg and Grant,

It's been 3 weeks this patch was posted by Linus. I'd like to know if this will
be merged in rc4/rc5, or not. If not, I have a revert to apply to the 4.0 tree.

Cheers.

-- 
Robert