From 87e77e46c61a9333227ab41cdefb1875758a4f13 Mon Sep 17 00:00:00 2001
From: Dirk Behme <dirk.behme@gmail.com>
Date: Wed, 2 Sep 2015 20:07:10 +0200
Subject: [PATCH] Documentation: gpio: board: describe the con_id parameter
The con_id parameter has to match the GPIO description and is automatically
extended by the GPIO suffix if not NULL. I had to look into the code to
understand this and properly find the GPIO I've been looking for, so document
this.
Signed-off-by: Dirk Behme <dirk.behme@gmail.com>
Acked-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
Documentation/gpio/board.txt | 9 +++++++++
Documentation/gpio/consumer.txt | 3 +++
2 files changed, 12 insertions(+)
diff --git a/Documentation/gpio/board.txt b/Documentation/gpio/board.txt
index 9edd5af31b3a4a..5fa069a8017140 100644
--- a/Documentation/gpio/board.txt
+++ b/Documentation/gpio/board.txt
@@ -48,6 +48,15 @@ This property will make GPIOs 15, 16 and 17 available to the driver under the
The led GPIOs will be active-high, while the power GPIO will be active-low (i.e.
gpiod_is_active_low(power) will be true).
+The second parameter of the gpiod_get() functions, the con_id string, has to be
+the <function>-prefix of the GPIO suffixes ("gpios" or "gpio", automatically
+looked up by the gpiod functions internally) used in the device tree. With above
+"led-gpios" example, use the prefix without the "-" as con_id parameter: "led".
+
+Internally, the GPIO subsystem prefixes the GPIO suffix ("gpios" or "gpio")
+with the string passed in con_id to get the resulting string
+(snprintf(... "%s-%s", con_id, gpio_suffixes[]).
+
ACPI
----
ACPI also supports function names for GPIOs in a similar fashion to DT.
diff --git a/Documentation/gpio/consumer.txt b/Documentation/gpio/consumer.txt
index a206639454ab7a..e000502fde2006 100644
--- a/Documentation/gpio/consumer.txt
+++ b/Documentation/gpio/consumer.txt
@@ -39,6 +39,9 @@ device that displays digits), an additional index argument can be specified:
const char *con_id, unsigned int idx,
enum gpiod_flags flags)
+For a more detailed description of the con_id parameter in the DeviceTree case
+see Documentation/gpio/board.txt
+
The flags parameter is used to optionally specify a direction and initial value
for the GPIO. Values can be:
--
GitLab