linux-kernel - [PATCH] gpiolib: fix bug and clarify OF use of ranges

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Date:	Wed, 21 Nov 2012 08:37:45 +0100
From:	Linus Walleij <linus.walleij@...ricsson.com>
To:	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	Shiraz Hashim <shiraz.hashim@...com>,
	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	Stephen Warren <swarren@...dia.com>,
	Anmar Oueja <anmar.oueja@...aro.org>,
	Grant Likely <grant.likely@...retlab.ca>,
	Linus Walleij <linus.walleij@...aro.org>
Subject: [PATCH] gpiolib: fix bug and clarify OF use of ranges

From: Linus Walleij <linus.walleij@...aro.org>

In commit c905165f5946f56dca195871641bd4e488eca24a
"gpiolib: let gpiochip_add_pin_range() specify offset"
I forgot to update the OF use of the function
gpiochip_add_pin_range().

It turns out that this reveal a weakness in the
OF range mappings: ranges cannot currently be sparse.
So put in a comment so we can fix this later.

Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
---
 drivers/gpio/gpiolib-of.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index a40cd84..d542a14 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -238,8 +238,20 @@ static void of_gpiochip_add_pin_range(struct gpio_chip *chip)
 		if (!pctldev)
 			break;
 
+		/*
+		 * This assumes that the n GPIO pins are consecutive in the
+		 * GPIO number space, and that the pins are also consecutive
+		 * in their local number space. Currently it is not possible
+		 * to add different ranges for one and the same GPIO chip,
+		 * as the code assumes that we have one consecutive range
+		 * on both, mapping 1-to-1.
+		 *
+		 * TODO: make the OF bindings handle multiple sparse ranges
+		 * on the same GPIO chip.
+		 */
 		ret = gpiochip_add_pin_range(chip,
 					     pinctrl_dev_get_name(pctldev),
+					     0, /* offset in gpiochip */
 					     pinspec.args[0],
 					     pinspec.args[1]);
 
-- 
1.7.11.3

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