gpio/mmc/of: Respect polarity in the device tree
diff mbox series

Message ID 20181217220216.22233-1-linus.walleij@linaro.org
State New
Headers show
Series
  • gpio/mmc/of: Respect polarity in the device tree
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Commit Message

Linus Walleij Dec. 17, 2018, 10:02 p.m. UTC
The device tree bindings for the MMC card detect and
write protect lines specify that these should be active
low unless "cd-inverted" or "wp-inverted" has been
specified.

However that is not how the kernel code has worked. It
has always respected the flags passed to the phandle in
the device tree, but respected the "cd-inverted" and
"wp-inverted" flags such that if those are set, the
polarity will be the inverse of that specified in the
device tree.

Switch to behaving like the old code did and fix the
regression.

Fixes: 81c85ec15a19 ("gpio: OF: Parse MMC-specific CD and WP properties")
Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
Ulf: I will apply this to the GPIO tree because of
patches hitting this code, things should work fine
in linux-next and in the merge window.
---
 drivers/gpio/gpiolib-of.c | 49 +++++++++++++--------------------------
 1 file changed, 16 insertions(+), 33 deletions(-)

Patch
diff mbox series

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index fa8044228f0e..a6e1891217e2 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -54,6 +54,7 @@  static struct gpio_desc *of_xlate_and_get_gpiod_flags(struct gpio_chip *chip,
 }
 
 static void of_gpio_flags_quirks(struct device_node *np,
+				 const char *propname,
 				 enum of_gpio_flags *flags,
 				 int index)
 {
@@ -61,39 +62,21 @@  static void of_gpio_flags_quirks(struct device_node *np,
 	 * Handle MMC "cd-inverted" and "wp-inverted" semantics.
 	 */
 	if (IS_ENABLED(CONFIG_MMC)) {
-		if (of_property_read_bool(np, "cd-gpios")) {
-			if (of_property_read_bool(np, "cd-inverted")) {
-				if (*flags & OF_GPIO_ACTIVE_LOW) {
-					/* "cd-inverted" takes precedence */
-					*flags &= ~OF_GPIO_ACTIVE_LOW;
-					pr_warn("%s GPIO handle specifies CD active low - ignored\n",
-						of_node_full_name(np));
-				}
-			} else {
-				/*
-				 * Active low is the default according to the
-				 * SDHCI specification. If the GPIO handle
-				 * specifies the same thing - good.
-				 */
-				*flags |= OF_GPIO_ACTIVE_LOW;
-			}
+		/*
+		 * Active low is the default according to the
+		 * SDHCI specification and the device tree
+		 * bindings. However the code in the current
+		 * kernel was written such that the phandle
+		 * flags were always respected, and "cd-inverted"
+		 * would invert the flag from the device phandle.
+		 */
+		if (!strcmp(propname, "cd-gpios")) {
+			if (of_property_read_bool(np, "cd-inverted"))
+				*flags ^= OF_GPIO_ACTIVE_LOW;
 		}
-		if (of_property_read_bool(np, "wp-gpios")) {
-			if (of_property_read_bool(np, "wp-inverted")) {
-				/* "wp-inverted" takes precedence */
-				if (*flags & OF_GPIO_ACTIVE_LOW) {
-					*flags &= ~OF_GPIO_ACTIVE_LOW;
-					pr_warn("%s GPIO handle specifies WP active low - ignored\n",
-						of_node_full_name(np));
-				}
-			} else {
-				/*
-				 * Active low is the default according to the
-				 * SDHCI specification. If the GPIO handle
-				 * specifies the same thing - good.
-				 */
-				*flags |= OF_GPIO_ACTIVE_LOW;
-			}
+		if (!strcmp(propname, "wp-gpios")) {
+			if (of_property_read_bool(np, "wp-inverted"))
+				*flags ^= OF_GPIO_ACTIVE_LOW;
 		}
 	}
 	/*
@@ -213,7 +196,7 @@  struct gpio_desc *of_get_named_gpiod_flags(struct device_node *np,
 		goto out;
 
 	if (flags)
-		of_gpio_flags_quirks(np, flags, index);
+		of_gpio_flags_quirks(np, propname, flags, index);
 
 	pr_debug("%s: parsed '%s' property of node '%pOF[%d]' - status (%d)\n",
 		 __func__, propname, np, index,