altos/stm: Semantic error in STM usb disable caused it to not work

The USB enable register wasn't actually getting rewritten with the
enable bit turned off, so the USB device was still powered on in flight.

Signed-off-by: Keith Packard <keithp@keithp.com>

diff --git a/src/stm/ao_usb_stm.c b/src/stm/ao_usb_stm.c
index b00390ec0318b14901a68156ad29597df5b08f2f..28a9f9f3e4643beac09b0db8a0dcf6e56c348fc9 100644 (file)
--- a/src/stm/ao_usb_stm.c
+++ b/src/stm/ao_usb_stm.c
@@ -965,7 +965,7 @@ ao_usb_disable(void)
        stm_usb.cntr = (1 << STM_USB_CNTR_PDWN) | (1 << STM_USB_CNTR_FRES);
 
        /* Disable the interface */
-       stm_rcc.apb1enr &+ ~(1 << STM_RCC_APB1ENR_USBEN);
+       stm_rcc.apb1enr &= ~(1 << STM_RCC_APB1ENR_USBEN);
        ao_arch_release_interrupts();
 }