From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/2] ARM: dts: imx6q: Invert the GPIO controller order
Date: Mon, 30 Jul 2012 15:24:43 +0100 [thread overview]
Message-ID: <20120730142443.GL6802@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <8E7BE7398BB9294F8B826ADE09B18EBE6CC2FF7EE1@SI-MBX20.de.bosch.com>
On Mon, Jul 30, 2012 at 09:28:21AM +0200, Thomae Matthias (CM-AI/PJ-CF31) wrote:
> I care about the global number because it is used to access GPIOs
> from userspace via the Sysfs interface (see Documentation/gpio.txt).
> Without the 2 patches, the GPIOs are mapped this way:
>
> gpiochip_add: registered GPIOs 224 to 255 on device: 209c000.gpio
> gpiochip_add: registered GPIOs 192 to 223 on device: 20a0000.gpio
> gpiochip_add: registered GPIOs 160 to 191 on device: 20a4000.gpio
> gpiochip_add: registered GPIOs 128 to 159 on device: 20a8000.gpio
> gpiochip_add: registered GPIOs 96 to 127 on device: 20ac000.gpio
> gpiochip_add: registered GPIOs 64 to 95 on device: 20b0000.gpio
> gpiochip_add: registered GPIOs 32 to 63 on device: 20b4000.gpio
>
> With the patches, the mapping looks like this:
>
> gpiochip_add: registered GPIOs 192 to 223 on device: 20b4000.gpio
> gpiochip_add: registered GPIOs 160 to 191 on device: 20b0000.gpio
> gpiochip_add: registered GPIOs 128 to 159 on device: 20ac000.gpio
> gpiochip_add: registered GPIOs 96 to 127 on device: 20a8000.gpio
> gpiochip_add: registered GPIOs 64 to 95 on device: 20a4000.gpio
> gpiochip_add: registered GPIOs 32 to 63 on device: 20a0000.gpio
> gpiochip_add: registered GPIOs 0 to 31 on device: 209c000.gpio
>
> I.e. pin 0 on gpio1 is now accessed via /sys/class/gpio/gpio0
> instead of /sys/class/gpio/gpio224.
I think you're caring too much about the numbers you see within the Linux
kernel...
So what happens when your platform is built as part of a single zImage
along side a platform needing all the 256 GPIOs? If the answer is "it
doesn't work" you need to go back and re-evaluate what you're doing.
Especially with DT, you shouldn't need to worry about the absolute GPIO
numbering.
next prev parent reply other threads:[~2012-07-30 14:24 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-25 12:37 [PATCH 1/2] ARM: i.MX6: set ARCH_NR_GPIO to 244 Dirk Behme
2012-07-25 12:37 ` [PATCH 2/2] ARM: dts: imx6q: Invert the GPIO controller order Dirk Behme
2012-07-28 13:41 ` Shawn Guo
2012-07-30 7:28 ` Thomae Matthias (CM-AI/PJ-CF31)
2012-07-30 9:01 ` Shawn Guo
2012-07-30 14:24 ` Russell King - ARM Linux [this message]
2012-07-31 8:15 ` Dirk Behme
2012-07-25 14:12 ` [PATCH 1/2] ARM: i.MX6: set ARCH_NR_GPIO to 244 Fabio Estevam
2012-07-25 14:51 ` Dirk Behme
2012-07-28 13:32 ` Shawn Guo
2012-07-29 16:18 ` Dirk Behme
2012-07-30 1:14 ` Shawn Guo
2012-07-30 6:40 ` Dirk Behme
2012-07-30 8:46 ` Shawn Guo
2012-07-30 11:14 ` Dirk Behme
2012-07-30 14:29 ` Russell King - ARM Linux
2012-07-31 1:16 ` Shawn Guo
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