On Thu, Jan 30, 2014 at 3:32 PM, Steffen Trumtrar
[off-list ref] wrote:

On Thu, Jan 30, 2014 at 03:15:11PM -0600, delicious quinoa wrote:

quoted

On Thu, Jan 30, 2014 at 2:50 PM, Steffen Trumtrar
[off-list ref] wrote:

quoted

Hi!

On Thu, Jan 30, 2014 at 01:40:04PM -0600, delicious quinoa wrote:

quoted

On Thu, Dec 12, 2013 at 3:08 AM, Steffen Trumtrar
[off-list ref] wrote:

quoted

Second: The interrupt is registered as "GIC 37", which is a real interrupt on
the Socfpga. I would expect it to be marked as "GPIO 2xx" (or something in that
range). The interrupt from the gpiochip itself isn't registered at all ?!

Hi Stephen,

Did you export the gpio lines and set the edge in sysfs?  Because the
interrupts aren't allocated otherwise.

For instance:

root@socfpga_cyclone5:~# echo 195 > /sys/class/gpio/export
root@socfpga_cyclone5:~# echo rising > /sys/class/gpio/gpio195/edge

Now I can see a pretty nicely named interrupt in /proc/interrupts:

256:          0          0  gpio-dwapb  24  gpiolib

I didn't try that and I think this behaviour is pretty uncommon.
This should be fixed in the driver. I never wrote a gpiochip-driver,
so I don't know what is missing, but maybe just some functioncall ?!
All other drivers I came across have that entry from probing without
any fiddling.

Hi Steffen,

Do you mean 'all other gpio drivers' or 'all other non-gpio drivers'?

I meant gpio drivers (at least the ones I have used).

quoted

This is the behavior that is implemented in the community gpio
framework drivers/gpio/gpiolib.c, not anything special implemented in
this dw gpio driver.

It's documented in Documentation/gpio/sysfs.txt and
Documentation/ABI/testing/sysfs-gpio.

You get userspace control of a gpio by 'export'ing it in sysfs.  And
then by default, the interrupt edge is set to 'none' (no irq) until
you set the edge in sysfs.

Hm, okay...for GPIOs I'm with you. But when I specify a gpio as
interrupt for a device, I have to first export it manually before I can
use the device? Sounds weird.

Steffen

Seems normal usage both in userspace and in kernel drivers that need a gpio.

Looking at other kernel drivers that use a gpio, I can see examples
that do gpio_request() to get the gpio that they care about.  Then
gpio_to_irq() and request_irq().  If you grep for 'gpio_to_irq' then
look to see how they got the gpio, you'll see it pretty quickly.

Alan