When generalising GPIO support and adding support for CP2102N, the GPIO registration for some CP2105 devices accidentally broke. Specifically, when all the pins of a port are in "modem" mode, and thus unavailable for GPIO use, the GPIO chip would now be registered without having initialised the number of GPIO lines. This would in turn be rejected by gpiolib and some errors messages would be printed (but importantly probe would still succeed).
Fix this by initialising the number of GPIO lines before registering the GPIO chip.
Note that as for the other device types, and as when all CP2105 pins are muxed for LED function, the GPIO chip is registered also when no pins are available for GPIO use.
Reported-by: Maarten Brock m.brock@vanmierlo.com Link: https://lore.kernel.org/r/5eb560c81d2ea1a2b4602a92d9f48a89@vanmierlo.com Fixes: c8acfe0aadbe ("USB: serial: cp210x: implement GPIO support for CP2102N") Cc: stable@vger.kernel.org # 4.19 Cc: Karoly Pados pados@pados.hu Signed-off-by: Johan Hovold johan@kernel.org --- drivers/usb/serial/cp210x.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c index 7705328034ca..8a60c0d56863 100644 --- a/drivers/usb/serial/cp210x.c +++ b/drivers/usb/serial/cp210x.c @@ -1635,6 +1635,8 @@ static int cp2105_gpioconf_init(struct usb_serial *serial)
/* 2 banks of GPIO - One for the pins taken from each serial port */ if (intf_num == 0) { + priv->gc.ngpio = 2; + if (mode.eci == CP210X_PIN_MODE_MODEM) { /* mark all GPIOs of this interface as reserved */ priv->gpio_altfunc = 0xff; @@ -1645,8 +1647,9 @@ static int cp2105_gpioconf_init(struct usb_serial *serial) priv->gpio_pushpull = (u8)((le16_to_cpu(config.gpio_mode) & CP210X_ECI_GPIO_MODE_MASK) >> CP210X_ECI_GPIO_MODE_OFFSET); - priv->gc.ngpio = 2; } else if (intf_num == 1) { + priv->gc.ngpio = 3; + if (mode.sci == CP210X_PIN_MODE_MODEM) { /* mark all GPIOs of this interface as reserved */ priv->gpio_altfunc = 0xff; @@ -1657,7 +1660,6 @@ static int cp2105_gpioconf_init(struct usb_serial *serial) priv->gpio_pushpull = (u8)((le16_to_cpu(config.gpio_mode) & CP210X_SCI_GPIO_MODE_MASK) >> CP210X_SCI_GPIO_MODE_OFFSET); - priv->gc.ngpio = 3; } else { return -ENODEV; }