enhance usb control loop

kernel/src/main.rs

@@ -24,7 +24,7 @@ use crate::{
 use {defmt_rtt as _, panic_probe as _};
 
 use embassy_executor::Spawner;
-use embassy_futures::join::join3;
+use embassy_futures::join::{join, join3};
 use embassy_rp::{
     gpio::{Input, Level, Output, Pull},
     peripherals::{I2C1, USB},
@@ -32,6 +32,7 @@ use embassy_rp::{
     usb as embassy_rp_usb,
 };
 use embassy_rp::{i2c, i2c::I2c, spi};
+use embassy_sync::{blocking_mutex::raw::ThreadModeRawMutex, signal::Signal};
 use embassy_time::{Delay, Timer};
 use embedded_hal_bus::spi::ExclusiveDevice;
 use embedded_sdmmc::SdCard as SdmmcSdCard;
@@ -41,6 +42,9 @@ embassy_rp::bind_interrupts!(struct Irqs {
     USBCTRL_IRQ => embassy_rp_usb::InterruptHandler<USB>;
 });
 
+// Controls the usb running to prevents sdcard writes via scsi and by the kernel
+static USB_ENABLED: Signal<ThreadModeRawMutex, bool> = Signal::new();
+
 #[embassy_executor::main]
 async fn main(_spawner: Spawner) {
     let p = embassy_rp::init(Default::default());
@@ -86,7 +90,8 @@ async fn main(_spawner: Spawner) {
     };
 
     let usb = embassy_rp_usb::Driver::new(p.USB, Irqs);
+    USB_ENABLED.signal(true);
     let usb_fut = usb_handler(usb, sdcard);
 
-    join3(async { loop {} }, usb_fut, display_fut).await;
+    join(usb_fut, display_fut).await;
 }

kernel/src/usb.rs

@@ -1,5 +1,5 @@
-use crate::{scsi::MassStorageClass, storage::SdCard};
-use embassy_futures::select::select;
+use crate::{USB_ENABLED, scsi::MassStorageClass, storage::SdCard};
+use embassy_futures::{join::join, select::select3};
 use embassy_rp::{peripherals::USB, usb::Driver};
 use embassy_usb::{Builder, Config};
 
@@ -28,9 +28,19 @@ pub async fn usb_handler(driver: Driver<'static, USB>, sdcard: SdCard) {
     let mut usb = builder.build();
 
     loop {
-        select(usb.run(), scsi.poll()).await;
-
-        defmt::warn!("rebuilding usb");
-        usb.disable().await;
+        if USB_ENABLED.wait().await {
+            select3(
+                async {
+                    loop {
+                        // stop usb task until usb is enabled again
+                        USB_ENABLED.wait().await;
+                        return; // breaks out of select
+                    }
+                },
+                usb.run(),
+                scsi.poll(),
+            )
+            .await;
+        }
     }
 }