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FAILED: patch "[PATCH] gpiolib: don't clear FLAG_IS_OUT when emulating" failed to apply to 4.9-stable tree

PATCH [email protected] 1 participant 1 message Oct 14, 2019

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The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e735244e2cf068f98b6384681a38993e0517a838 Mon Sep 17 00:00:00 2001
From: Bartosz Golaszewski <[email protected]>
Date: Tue, 1 Oct 2019 11:44:53 +0200
Subject: [PATCH] gpiolib: don't clear FLAG_IS_OUT when emulating
open-drain/open-source

When emulating open-drain/open-source by not actively driving the output lines - we're simply changing their mode to input. This is wrong as it will then make it impossible to change the value of such line - it's now considered to actually be in input mode. If we want to still use the direction_input() callback for simplicity then we need to set FLAG_IS_OUT manually in gpiod_direction_output() and not clear it in gpio_set_open_drain_value_commit() and gpio_set_open_source_value_commit().

Fixes c663e5f56737 ("gpio: support native single-ended hardware drivers")
Cc [email protected]
Reported-by Kent Gibson <[email protected]>
Signed-off-by Bartosz Golaszewski <[email protected]>
drivers/gpio/gpiolib.c +19 -8
index bdbc1649eafa..5833e4f380d6 100644
@@ -3070,8 +3070,10 @@ int gpiod_direction_output(struct gpio_desc *desc, int value)
 		if (!ret)
 			goto set_output_value;
 		/* Emulate open drain by not actively driving the line high */
-		if (value)
-			return gpiod_direction_input(desc);
+		if (value) {
+			ret = gpiod_direction_input(desc);
+			goto set_output_flag;
+		}
 	}
 	else if (test_bit(FLAG_OPEN_SOURCE, &desc->flags)) {
 		ret = gpio_set_config(gc, gpio_chip_hwgpio(desc),

@@ -3079,8 +3081,10 @@ int gpiod_direction_output(struct gpio_desc *desc, int value)
 		if (!ret)
 			goto set_output_value;
 		/* Emulate open source by not actively driving the line low */
-		if (!value)
-			return gpiod_direction_input(desc);
+		if (!value) {
+			ret = gpiod_direction_input(desc);
+			goto set_output_flag;
+		}
 	} else {
 		gpio_set_config(gc, gpio_chip_hwgpio(desc),
 				PIN_CONFIG_DRIVE_PUSH_PULL);

@@ -3088,6 +3092,17 @@ int gpiod_direction_output(struct gpio_desc *desc, int value)
 
 set_output_value:
 	return gpiod_direction_output_raw_commit(desc, value);
+
+set_output_flag:
+	/*
+	 * When emulating open-source or open-drain functionalities by not
+	 * actively driving the line (setting mode to input) we still need to
+	 * set the IS_OUT flag or otherwise we won't be able to set the line
+	 * value anymore.
+	 */
+	if (ret == 0)
+		set_bit(FLAG_IS_OUT, &desc->flags);
+	return ret;
 }
 EXPORT_SYMBOL_GPL(gpiod_direction_output);
 

@@ -3448,8 +3463,6 @@ static void gpio_set_open_drain_value_commit(struct gpio_desc *desc, bool value)
 
 	if (value) {
 		ret = chip->direction_input(chip, offset);
-		if (!ret)
-			clear_bit(FLAG_IS_OUT, &desc->flags);
 	} else {
 		ret = chip->direction_output(chip, offset, 0);
 		if (!ret)

@@ -3479,8 +3492,6 @@ static void gpio_set_open_source_value_commit(struct gpio_desc *desc, bool value
 			set_bit(FLAG_IS_OUT, &desc->flags);
 	} else {
 		ret = chip->direction_input(chip, offset);
-		if (!ret)
-			clear_bit(FLAG_IS_OUT, &desc->flags);
 	}
 	trace_gpio_direction(desc_to_gpio(desc), !value, ret);
 	if (ret < 0)