mmc: core: fix card detection regression

Since commit 89168b48 ("mmc: core: restore detect line inversion
semantics"), the SD card on i.MX28 (and possibly other) devices isn't
detected and booting stops at:

[    4.120617] Waiting for root device /dev/mmcblk0p3...

This is caused by the MMC_CAP2_CD_ACTIVE_HIGH flag being set incorrectly
when the host controller doesn't use a GPIO for card detection (but
instead uses a dedicated pin). In this case mmc_gpiod_request_cd() will
return before assigning to the gpio_invert variable, leaving the
variable uninitialized. The variable then gets used to set the flag.
This patch fixes the issue by making sure gpio_invert is set to false
when a GPIO isn't used. After this patch, i.MX28 boots fine.

The MMC_CAP2_RO_ACTIVE_HIGH (write protect) flag is also set incorrectly
for the exact same reason (it uses the same uninitialized variable), so
this patch fixes that too.

Fixes: 89168b48 ("mmc: core: restore detect line inversion semantics")
Reported-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Kristina Martšenko <kristina.martsenko@gmail.com>
Tested-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/core/host.c

@@ -311,7 +311,8 @@ int mmc_of_parse(struct mmc_host *host)
 	struct device_node *np;
 	u32 bus_width;
 	int len, ret;
-	bool cap_invert, gpio_invert;
+	bool cd_cap_invert, cd_gpio_invert = false;
+	bool ro_cap_invert, ro_gpio_invert = false;
 
 	if (!host->parent || !host->parent->of_node)
 		return 0;
@@ -359,16 +360,13 @@ int mmc_of_parse(struct mmc_host *host)
 	if (of_find_property(np, "non-removable", &len)) {
 		host->caps |= MMC_CAP_NONREMOVABLE;
 	} else {
-		if (of_property_read_bool(np, "cd-inverted"))
-			cap_invert = true;
-		else
-			cap_invert = false;
+		cd_cap_invert = of_property_read_bool(np, "cd-inverted");
 
 		if (of_find_property(np, "broken-cd", &len))
 			host->caps |= MMC_CAP_NEEDS_POLL;
 
 		ret = mmc_gpiod_request_cd(host, "cd", 0, true,
-					   0, &gpio_invert);
+					   0, &cd_gpio_invert);
 		if (ret) {
 			if (ret == -EPROBE_DEFER)
 				return ret;
@@ -391,17 +389,14 @@ int mmc_of_parse(struct mmc_host *host)
 		 * both inverted, the end result is that the CD line is
 		 * not inverted.
 		 */
-		if (cap_invert ^ gpio_invert)
+		if (cd_cap_invert ^ cd_gpio_invert)
 			host->caps2 |= MMC_CAP2_CD_ACTIVE_HIGH;
 	}
 
 	/* Parse Write Protection */
-	if (of_property_read_bool(np, "wp-inverted"))
-		cap_invert = true;
-	else
-		cap_invert = false;
+	ro_cap_invert = of_property_read_bool(np, "wp-inverted");
 
-	ret = mmc_gpiod_request_ro(host, "wp", 0, false, 0, &gpio_invert);
+	ret = mmc_gpiod_request_ro(host, "wp", 0, false, 0, &ro_gpio_invert);
 	if (ret) {
 		if (ret == -EPROBE_DEFER)
 			goto out;
@@ -414,7 +409,7 @@ int mmc_of_parse(struct mmc_host *host)
 		dev_info(host->parent, "Got WP GPIO\n");
 
 	/* See the comment on CD inversion above */
-	if (cap_invert ^ gpio_invert)
+	if (ro_cap_invert ^ ro_gpio_invert)
 		host->caps2 |= MMC_CAP2_RO_ACTIVE_HIGH;
 
 	if (of_find_property(np, "cap-sd-highspeed", &len))