linux-kernel - Re: [PATCH 2/2] pinctrl: rockchip: Fix enable/disable/mask/unmask

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Message-ID: <CAD=FV=XVyM2Fgf9nWr4+Do7DCLJ6WW2N9DGYs+Qbxtvd+WkYOA@mail.gmail.com>
Date:	Wed, 19 Nov 2014 10:48:28 -0800
From:	Doug Anderson <dianders@...omium.org>
To:	Heiko Stübner <heiko@...ech.de>
Cc:	Linus Walleij <linus.walleij@...aro.org>,
	Sonny Rao <sonnyrao@...omium.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Chris Zhong <zyw@...k-chips.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] pinctrl: rockchip: Fix enable/disable/mask/unmask

Heiko,

On Wed, Nov 19, 2014 at 10:46 AM, Heiko Stübner <heiko@...ech.de> wrote:
> Am Mittwoch, 19. November 2014, 09:54:13 schrieb Doug Anderson:
>> Hi,
>>
>> On Tue, Nov 18, 2014 at 3:49 PM, Doug Anderson <dianders@...omium.org>
> wrote:
>> > +static void rockchip_irq_disable(struct irq_data *d)
>> > +{
>> > +       struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
>> > +       u32 val;
>> > +
>> > +       irq_gc_lock(gc);
>> > +       val = irq_reg_readl(gc, GPIO_INTEN);
>> > +       irq_reg_writel(gc, val & ~d->mask, GPIO_INTEN);
>> > +       irq_gc_unlock(gc);
>> > +}
>>
>> Off list, Dmitry asked me why I didn't use irq_gc_mask_disable_reg()
>> and irq_gc_unmask_enable_reg() (AKA why I coded up my own function
>> here).  Originally I tried to use irq_gc_mask_disable_reg() and
>> irq_gc_unmask_enable_reg().  ..but they're really not designed to work
>> in tandem with the irq_gc_mask_set_bit() and irq_gc_mask_clr_bit().
>>
>> Specifically if you try to use one set of functions for your
>> mask/unmask and the other for your disable/enable you'll find that
>> they stomp on each other.  Both functions upkeep the exact same
>> "mask_cache" variable.
>>
>> Personally I'm totally baffled by how irq_gc_mask_disable_reg() and
>> irq_gc_unmask_enable_reg() could actually be sane, but that's maybe a
>> topic for another discussion.
>
> I don't think irq_gc_mask_disable_reg and irq_gc_unmask_enable_reg are meant
> as callbacks for irq_enable/irq_disable. As the name implies they are
> standardized callbacks for irq_mask/irq_unmask on machines using a different
> scheme for masking. So I would expected that they operate on the same
> mask_cache because both types of functions handle masking on different types of
> interrupt controllers.

Agreed that they aren't meant for irq_enable / irq_disable and that
it's not a bug.  It was just so tempting to use them and Dmitry
wondered the same thing, so I wrote an email detailing this.  Even
though these aren't for use as enable/disable, I will point out that
they don't seem sane (to me) for masking...


> There don't seem to be any generalized callbacks for irq_enable/irq_disable
> themself, probably because machines do the most uncommon things there :-)

Fair enough.  If it becomes common someone can move my functions
somewhere common.  ;)


Do you think this patch is something that should land?  Do I need to
prove that it's useful before we actually land it?  Right now I just
posted it because it seemed better, not because it fixes anything that
I know of.

-Doug
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