Hi Laurent, Linus,

On Tue, Jun 30, 2015 at 11:49 AM, Laurent Pinchart
[off-list ref] wrote:

On Tuesday 30 June 2015 09:45:21 Geert Uytterhoeven wrote:

quoted

If a GPIO driver uses gpiochip_add_pin_range() (which is usually the
case for GPIO/PFC combos), the GPIO hogging mechanism configured from DT
doesn't work:

    requesting hog GPIO led1-high (chip r8a73a4_pfc, offset 28) failed

The actual error code is -517 == -EPROBE_DEFER.

The problem is that PFC+GPIO registration is handled in multiple steps:
  1. pinctrl_register(),
  2. gpiochip_add(),
  3. gpiochip_add_pin_range().

Configuration of the hogs is handled in gpiochip_add():

    gpiochip_add
        of_gpiochip_add
            of_gpiochip_scan_hogs
                gpiod_hog
                    gpiochip_request_own_desc
                        __gpiod_request
                            chip->request
                                pinctrl_request_gpio
                                    pinctrl_get_device_gpio_range

However, at this point the GPIO controller hasn't been added to
pinctrldev_list yet, so the range can't be found, and the operation fails
with -EPROBE_DEFER.

To fix this, add a "gpio-ranges" property to the gpio device node, so
the ranges are added by of_gpiochip_add_pin_range(), which is called by
of_gpiochip_add() before the call to of_gpiochip_scan_hogs().

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

This looks sane to me, even though referencing the same DT node seems a bit
dodgy. I'll let Linus comment on that, but for the implementation itself,

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Thank you!

Any wise words from Linus?

Thanks again!

quoted

---
 arch/arm/boot/dts/r8a73a4.dtsi | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/arm/boot/dts/r8a73a4.dtsi b/arch/arm/boot/dts/r8a73a4.dtsi
index 5090d1a8f652e8be..cb4f7b2798fe23be 100644
--- a/arch/arm/boot/dts/r8a73a4.dtsi
+++ b/arch/arm/boot/dts/r8a73a4.dtsi

@@ -207,6 +207,13 @@
              reg = <0 0xe6050000 0 0x9000>;
              gpio-controller;
              #gpio-cells = <2>;
+             gpio-ranges =
+                     <&pfc 0 0 31>, <&pfc 32 32 9>,
+                     <&pfc 64 64 22>, <&pfc 96 96 31>,
+                     <&pfc 128 128 7>, <&pfc 160 160 19>,
+                     <&pfc 192 192 31>, <&pfc 224 224 27>,
+                     <&pfc 256 256 28>, <&pfc 288 288 21>,
+                     <&pfc 320 320 10>;
              interrupts-extended =
                      <&irqc0  0 0>, <&irqc0  1 0>, <&irqc0  2 0>, <&irqc0  3 0>,
                      <&irqc0  4 0>, <&irqc0  5 0>, <&irqc0  6 0>, <&irqc0  7 0>,

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds