[PATCH] mmc: pwrseq_simple: fix probe failure when CONFIG_RESET_GPIO is enabled

[Sergey Suloev]

The driver uses a heuristic — checking if exactly one entry exists in
'reset-gpios' — to decide whether to attempt reset controller API usage
via devm_reset_control_get_optional_shared(). This is semantically
incorrect and causes a permanent probe failure when CONFIG_RESET_GPIO
is enabled.

When CONFIG_RESET_GPIO=y, __of_reset_control_get() intercepts the
'reset-gpios' DT property and attempts to register the GPIO as a reset
controller via __reset_add_reset_gpio_device(). If the GPIO controller
is not yet fully initialized at probe time, this returns -ENOENT instead
of -EPROBE_DEFER, and the error path does not respect the 'optional'
flag, causing pwrseq_simple to fail permanently rather than defer.
This prevents mmc1 from probing on boards that use 'reset-gpios' for
WiFi power sequencing, such as BananaPi M2 Magic with AP6212/BCM43430
on Allwinner R16.

The correct indicator of reset controller intent is the explicit presence
of a 'resets' property in the device tree node, not the count of
'reset-gpios' entries. A single 'reset-gpios' entry is just as likely
to be a plain GPIO as multiple entries.

Replace the ngpio == 1 heuristic with an explicit check for the 'resets'
DT property, making the behavior unambiguous and immune to
CONFIG_RESET_GPIO interference.

Fixes: 73bf4b7381f7 ("mmc: pwrseq_simple: add support for one reset control")
Signed-off-by: Sergey Suloev <sergey.suloev@xxxxxxxxx>
---
 drivers/mmc/core/pwrseq_simple.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/mmc/core/pwrseq_simple.c b/drivers/mmc/core/pwrseq_simple.c
index 4b47e6c3b04b..780c8818a273 100644
--- a/drivers/mmc/core/pwrseq_simple.c
+++ b/drivers/mmc/core/pwrseq_simple.c
@@ -124,7 +124,6 @@ static int mmc_pwrseq_simple_probe(struct platform_device *pdev)
 {
 	struct mmc_pwrseq_simple *pwrseq;
 	struct device *dev = &pdev->dev;
-	int ngpio;
 
 	pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
 	if (!pwrseq)
@@ -134,8 +133,7 @@ static int mmc_pwrseq_simple_probe(struct platform_device *pdev)
 	if (IS_ERR(pwrseq->ext_clk) && PTR_ERR(pwrseq->ext_clk) != -ENOENT)
 		return dev_err_probe(dev, PTR_ERR(pwrseq->ext_clk), "external clock not ready\n");
 
-	ngpio = of_count_phandle_with_args(dev->of_node, "reset-gpios", "#gpio-cells");
-	if (ngpio == 1) {
+	if (device_property_present(dev, "resets")) {
 		pwrseq->reset_ctrl = devm_reset_control_get_optional_shared(dev, NULL);
 		if (IS_ERR(pwrseq->reset_ctrl))
 			return dev_err_probe(dev, PTR_ERR(pwrseq->reset_ctrl),
-- 
2.43.0