linux-kernel - Re: [PATCH v2 2/2] gpio: Add support for Intel Cherryview/Braswell GPIO controller

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Date:	Wed, 24 Sep 2014 12:29:30 +0300
From:	Mika Westerberg <mika.westerberg@...ux.intel.com>
To:	Linus Walleij <linus.walleij@...aro.org>
Cc:	Alexandre Courbot <gnurou@...il.com>,
	Arnd Bergmann <arnd@...db.de>, Alan Cox <alan@...ux.intel.com>,
	Ning Li <ning.li@...el.com>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] gpio: Add support for Intel Cherryview/Braswell
 GPIO controller

On Wed, Sep 24, 2014 at 11:10:39AM +0200, Linus Walleij wrote:
> On Mon, Sep 15, 2014 at 4:09 PM, Mika Westerberg
> <mika.westerberg@...ux.intel.com> wrote:
> 
> > From: Ning Li <ning.li@...el.com>
> >
> > This driver supports the GPIO controllers found in newer Intel SoCs like
> > Cherryview and Braswell.
> >
> > Signed-off-by: Ning Li <ning.li@...el.com>
> > Signed-off-by: Alan Cox <alan@...ux.intel.com>
> > Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> (...)
> > +#define FAMILY0_PAD_REGS_OFF   0x4400
> > +#define FAMILY_PAD_REGS_SIZE   0x400
> > +#define MAX_FAMILY_PAD_GPIO_NO 15
> 
> Pad registers...
> 
> > +static const char * const north_pads[] = {
> > +       "GPIO_DFX_0",
> > +       "GPIO_DFX_3",
> > +       "GPIO_DFX_7",
> > +       "GPIO_DFX_1",
> > +       "GPIO_DFX_5",
> > +       "GPIO_DFX_4",
> > +       "GPIO_DFX_8",
> > +       "GPIO_DFX_2",
> > +       "GPIO_DFX_6",
> 
> And then even naming them and stuff.
> 
> This is almost a schoolbook definition of stuff that pertains
> to the pin control subsystem rather than GPIO, and this
> info in particular shall be encoded in the .pins field of
> the struct pinctrl_desc. Which is where we name pins.
> 
> > +               switch ((ctrl0 & CV_GPIO_CFG_MASK) >> 8) {
> > +               case 0:
> > +                       dir = "in out";
> > +                       break;
> > +               case 1:
> > +                       dir = "   out";
> > +                       break;
> > +               case 2:
> > +                       dir = "in";
> > +                       break;
> > +               case 3:
> > +                       dir = "HiZ";
> > +                       break;
> 
> And here there is even pin config like HiZ, which is in the kernel
> called PIN_CONFIG_BIAS_HIGH_IMPEDANCE with generic
> pin config.
> 
> In short it seems the driver is written by someone who has never
> heard of pin control or doesn't realize that this is exactly what
> pin control is about.

Heh, I actually looked into pinctrl but somehow couldn't find any fit
there.

> Read Documentation/pinctrl.txt and rewrite the entire driver to
> use pin control, and generic pin config like everyone else.

Will do, thanks.
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