linux-kernel - [PATCH for 4.15] leds: pca955x: Fix configuration on GPIO request for input

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Date:   Wed,  4 Oct 2017 17:57:01 +1030
From:   Andrew Jeffery <andrew@...id.au>
To:     linux-leds@...r.kernel.org
Cc:     Andrew Jeffery <andrew@...id.au>, jacek.anaszewski@...il.com,
        pavel@....cz, linux-kernel@...r.kernel.org,
        Cédric Le Goater <clg@...d.org>,
        Joel Stanley <joel@....id.au>
Subject: [PATCH for 4.15] leds: pca955x: Fix configuration on GPIO request for input

The prior patch which fixed the problem with output inversion failed to
account for a necessary change to requesting a pin for input, which is
affected by the open-drain nature of the hardware.

Previously pca955x_gpio_direction_input() called through
pca955x_set_value() to configure the direction, however continuing down
this route lead to a brain-hemorrhaging level of necessary inversions.
Instead, remove one layer by calling directly into pca955x_led_set(),
and define PCA955X_GPIO_INPUT to paper over the rest of the confusion.

Cc: Cédric Le Goater <clg@...d.org>
Cc: Joel Stanley <joel@....id.au>
Signed-off-by: Andrew Jeffery <andrew@...id.au>
Tested-by: Matt Spinler <mspinler@...ux.vnet.ibm.com>
---
Jacek:

The prior patch called out above is "eae1693fb026 leds: pca955x: Don't
invert requested value in pca955x_gpio_set_value()" (at the time of sending). I
think I've seen the leds tree be rebased in the past, so feel free to squash
this change in if desired.

 drivers/leds/leds-pca955x.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/leds/leds-pca955x.c b/drivers/leds/leds-pca955x.c
index 6dcd2d7cc6a4..78183f90820e 100644
--- a/drivers/leds/leds-pca955x.c
+++ b/drivers/leds/leds-pca955x.c
@@ -61,6 +61,7 @@
 #define PCA955X_LS_BLINK0	0x2	/* Blink at PWM0 rate */
 #define PCA955X_LS_BLINK1	0x3	/* Blink at PWM1 rate */

+#define PCA955X_GPIO_INPUT	LED_OFF
 #define PCA955X_GPIO_HIGH	LED_OFF
 #define PCA955X_GPIO_LOW	LED_FULL

@@ -358,8 +359,11 @@ static int pca955x_gpio_get_value(struct gpio_chip *gc, unsigned int offset)
 static int pca955x_gpio_direction_input(struct gpio_chip *gc,
 					unsigned int offset)
 {
-	/* To use as input ensure pin is not driven */
-	return pca955x_set_value(gc, offset, 0);
+	struct pca955x *pca955x = gpiochip_get_data(gc);
+	struct pca955x_led *led = &pca955x->leds[offset];
+
+	/* To use as input ensure pin is not driven. */
+	return pca955x_led_set(&led->led_cdev, PCA955X_GPIO_INPUT);
 }

 static int pca955x_gpio_direction_output(struct gpio_chip *gc,
-- 
2.11.0