mmc: core: restore detect line inversion semantics

commit 98e90de99a0c43bd434da814c882c4332441871e
"mmc: host: switch OF parser to use gpio descriptors"
switched the semantic behaviour of card detect and read
only flags such that the inversion capability flag would
only be set if inversion was explicitly specified in the
device tree, in the hopes that no-one was using double
inversion.

It turns out that the XOR:ing between the explicit
inversion was indeed in use, so we need to restore the
old semantics where both ways of inversion are checked
and the end result XOR:ed.

Reported-by: Javier Martinez Canillas <javier@dowhile0.org>
Tested-by: Javier Martinez Canillas <javier@dowhile0.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
diff --git a/drivers/mmc/core/slot-gpio.c b/drivers/mmc/core/slot-gpio.c
index 38f7655..69bbf2a 100644
--- a/drivers/mmc/core/slot-gpio.c
+++ b/drivers/mmc/core/slot-gpio.c
@@ -281,6 +281,8 @@
  * @idx: index of the GPIO to obtain in the consumer
  * @override_active_level: ignore %GPIO_ACTIVE_LOW flag
  * @debounce: debounce time in microseconds
+ * @gpio_invert: will return whether the GPIO line is inverted or not, set
+ * to NULL to ignore
  *
  * Use this function in place of mmc_gpio_request_cd() to use the GPIO
  * descriptor API.  Note that it is paired with mmc_gpiod_free_cd() not
@@ -291,7 +293,7 @@
  */
 int mmc_gpiod_request_cd(struct mmc_host *host, const char *con_id,
 			 unsigned int idx, bool override_active_level,
-			 unsigned int debounce)
+			 unsigned int debounce, bool *gpio_invert)
 {
 	struct mmc_gpio *ctx;
 	struct gpio_desc *desc;
@@ -316,6 +318,9 @@
 			return ret;
 	}
 
+	if (gpio_invert)
+		*gpio_invert = !gpiod_is_active_low(desc);
+
 	ctx->override_cd_active_level = override_active_level;
 	ctx->cd_gpio = desc;
 
@@ -330,6 +335,8 @@
  * @idx: index of the GPIO to obtain in the consumer
  * @override_active_level: ignore %GPIO_ACTIVE_LOW flag
  * @debounce: debounce time in microseconds
+ * @gpio_invert: will return whether the GPIO line is inverted or not,
+ * set to NULL to ignore
  *
  * Use this function in place of mmc_gpio_request_ro() to use the GPIO
  * descriptor API.  Note that it is paired with mmc_gpiod_free_ro() not
@@ -339,7 +346,7 @@
  */
 int mmc_gpiod_request_ro(struct mmc_host *host, const char *con_id,
 			 unsigned int idx, bool override_active_level,
-			 unsigned int debounce)
+			 unsigned int debounce, bool *gpio_invert)
 {
 	struct mmc_gpio *ctx;
 	struct gpio_desc *desc;
@@ -364,6 +371,9 @@
 			return ret;
 	}
 
+	if (gpio_invert)
+		*gpio_invert = !gpiod_is_active_low(desc);
+
 	ctx->override_ro_active_level = override_active_level;
 	ctx->ro_gpio = desc;