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From:   Bartosz Golaszewski <bgolaszewski@baylibre.com>
Date:   Tue, 12 Feb 2019 13:29:39 +0100
Message-ID: <CAMpxmJWXOb1HW4QiEn8gMp3Nh05ahE0CMLXkac+hEKRjtGxTHQ@mail.gmail.com>
Subject: Re: [PATCH v4 05/10] mfd: max77650: new core mfd driver
To:     Lee Jones <lee.jones@linaro.org>
Cc:     Bartosz Golaszewski <brgl@bgdev.pl>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Jacek Anaszewski <jacek.anaszewski@gmail.com>,
        Pavel Machek <pavel@ucw.cz>,
        Sebastian Reichel <sre@kernel.org>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
        devicetree <devicetree@vger.kernel.org>,
        Linux Input <linux-input@vger.kernel.org>,
        Linux LED Subsystem <linux-leds@vger.kernel.org>,
        Linux PM list <linux-pm@vger.kernel.org>
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wt., 12 lut 2019 o 12:14 Lee Jones <lee.jones@linaro.org> napisa=C5=82(a):
>
> On Tue, 12 Feb 2019, Bartosz Golaszewski wrote:
>
> > wt., 12 lut 2019 o 11:18 Lee Jones <lee.jones@linaro.org> napisa=C5=82(=
a):
> > >
> > > On Tue, 12 Feb 2019, Bartosz Golaszewski wrote:
> > >
> > > > wt., 12 lut 2019 o 10:55 Lee Jones <lee.jones@linaro.org> napisa=C5=
=82(a):
> > > > >
> > > > >  * The declaration of a superfluous struct
> > > > >  * 100 lines of additional/avoidable code
> > > > >  * Hacky hoop jumping trying to fudge VIRQs into resources
> > > > >  * Resources were designed for HWIRQs (unless a domain is present=
)
> > > > >  * Loads of additional/avoidable CPU cycles setting all this up
> > > >
> > > > While the above may be right, this one is negligible and you know i=
t. :)
> > >
> > > You have nested for() loops.  You *are* wasting lots of cycles.
> > >
> > > > > Need I go on? :)
> > > > >
> > > > > Surely the fact that you are using both sides of an API
> > > > > (devm_regmap_init_i2c and regmap_irq_get_*) in the same driver, m=
ust
> > > > > set some alarm bells ringing?
> > > > >
> > > > > This whole HWIRQ setting, VIRQ getting, resource hacking is a mes=
s.
> > > > >
> > > > > And for what?  To avoid passing IRQ data to a child driver?
> > > >
> > > > What do you propose? Should I go back to the approach in v1 and pas=
s
> > > > the regmap_irq_chip_data to child drivers?
> > >
> > > I'm saying you should remove all of this hackery and pass IRQs as the=
y
> > > are supposed to be passed (like everyone else does).
> >
> > I'm not sure what you mean by "like everyone else does" - different
> > mfd drivers seem to be doing different things. Is a simple struct
> > containing virtual irq numbers passed to sub-drivers fine?
>
> How do you plan on deriving the VIRQs to place into the struct?

Exampe:

struct max77650_gpio_pdata {
    int gpi_irq;
};

In MFD driver:

struct max77650_gpio_pdata *gpio_data =3D devm_kmalloc(dev, sizeof(*gpio_da=
ta));

gpio_data->gpi_irq =3D regmap_irq_get_virq(irqchip_data, GPI_NUM);

gpio_cell.platform_data =3D gpio_data;

In GPIO driver:

struct max77650_gpio_pdata *gpio_data =3D pdev->dev.platform_data;

int irq =3D gpio_data->gpi_irq;

Bart