lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Mon, 6 Oct 2014 09:18:41 +0200
From:	Sascha Hauer <s.hauer@...gutronix.de>
To:	Linus Walleij <linus.walleij@...aro.org>
Cc:	"Hongzhou.Yang" <srv_hongzhou.yang@...iatek.com>,
	Rob Herring <robh+dt@...nel.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	srv_heupstream@...iatek.com, Sascha Hauer <kernel@...gutronix.de>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Russell King <linux@....linux.org.uk>,
	Grant Likely <grant.likely@...aro.org>,
	Hongzhou Yang <hongzhou.yang@...iatek.com>,
	"Joe.C" <yingjoe.chen@...iatek.com>,
	Catalin Marinas <catalin.marinas@....com>,
	Vladimir Murzin <vladimir.murzin@....com>,
	Ashwin Chaugule <ashwin.chaugule@...aro.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>, dandan.he@...iatek.com
Subject: Re: [PATCH v2 4/4] ARM: dts: mt8135: Add pinctrl node for mt8135.

On Thu, Oct 02, 2014 at 04:02:58PM +0200, Linus Walleij wrote:
> On Wed, Sep 24, 2014 at 2:40 PM, Sascha Hauer <s.hauer@...gutronix.de> wrote:
> > On Wed, Sep 24, 2014 at 01:23:09PM +0200, Linus Walleij wrote:
> 
> >> I haven't got to reviewing the driver, but this looks just wrong.
> >>
> >> Have the magic numbers in the driver.
> >>
> >> Use strings to describe functions, not integers.
> >
> > Interrupts, clocks, gpios, dma channels, nearly everything in the device tree is
> > arbitrarily numbered. Instead of "irq-i2c0" we have <0 36 IRQ_TYPE_LEVEL_HIGH>
> > in the device tree. These numbers can be resolved efficiently in the
> > driver by shifting them to get a bitmask or by adding them as offset to
> > a register base.
> > Why do you want to make pinctrl different?
> 
> Because pin control is about combining groups of pins with
> certain functions.
> 
> > Thanks to the recently
> > introduced defines in the device trees these numbers are not magic at
> > all anymore.
> 
> Yeah that is good but not what I'm after here.
> 
> >> We need to move toward standardized device tree bindings
> >> for this stuff, and that means using strings, not magic
> >> numbers.
> >
> > Agreed for standardized device tree bindings, but not for using strings.
> 
> What is the alternative? Device Tree is very much about strings,
> as is shown by the pin config bindings.

The alternative is to use numbers. The majority of SoCs have a bit field
per pad which is used for muxing the pad to different functions. The
natural way to describe this is a pair of numbers: <pad-number>
<function-number>.  The pad number can normally be directly translated
into a register offset and the function number to a value written to
that register. This is true for most SoCs I know of and makes it very
easy to generate code for and to prove for correctness of both the code
and the device tree.

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists