linux-kernel - Re: [PATCH v3] regmap: regmap-irq/gpio-max77620: add level-irq support

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Message-ID: <20190102074251.GA8865@localhost.localdomain>
Date:   Wed, 2 Jan 2019 09:42:51 +0200
From:   Matti Vaittinen <matti.vaittinen@...rohmeurope.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        mazziesaccount@...il.com, heikki.haikola@...rohmeurope.com,
        mikko.mutanen@...rohmeurope.com,
        Greg KH <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Vladimir Zapolskiy <vladimir_zapolskiy@...tor.com>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH v3] regmap: regmap-irq/gpio-max77620: add level-irq
 support

On Mon, Dec 31, 2018 at 07:11:27PM +0000, Mark Brown wrote:
> On Fri, Dec 28, 2018 at 10:05:33AM +0200, Matti Vaittinen wrote:
> 
> > Last night - just when I was about to get some sleep - it stroke me. I
> > think the correct thing to do would be leaving the irq_set_type to NULL
> > for those IRQ chips which do not support type setting. If we do that,
> > then the irq core will take care of situations where user requests type
> > setting but the chip does not support it. Which means the regmap-irq
> > would be no different from any other irq chip where type setting is not
> > supported.
> 
> Yes, this is the best fix - let the framework handle things properly.
> We'll need a second set of operations and to select which to use based
> on having type information but that's fine.
> 
> > So at the cost of removing "const" from regmap_irq_chip we could do:
> 
> ...
> 
> > Mark, Geert, what do you think? (And maybe same for the .irq_set_wake -
> > but I did omit this as I have never looked at the wake functionality
> > before).
> 
> We need a separate struct as otherwise if there's multiple devices with
> regmap irq_chip implementations then they'll collide with each other

Right. I must admit I didn't notice this! I was about to make a nasty
error there...

> otherwise I like this approach (or we could copy the irq_chip struct
> when registering and then modify which is going to scale a bit better -

I am really not a fan of dynamic allocation - I'd rather had static
structs with different set of operations. But I admit I can't think of a
sane system where we would have more than few regmap_irq controllers so
memory consumption of allocating new structs is hardly an issue here. 

> you're probably right that we need to do the same thing for the wake
> configuration.  I'll still look at applying your patch as a temporary
> fix though.

Thanks Mark. I try to cook a patch with copying of struct irq_chip still
at this week but I wont rush it (I have some other topics under work) as
the regression should be fixed by the other patch.

Br,
	Matti Vaittinen

-- 
Matti Vaittinen
ROHM Semiconductors

~~~ "I don't think so," said Rene Descartes.  Just then, he vanished ~~~