diff --git a/xhcid/src/xhci/mod.rs b/xhcid/src/xhci/mod.rs
index ef8d103016..d3936d51c4 100644
--- a/xhcid/src/xhci/mod.rs
+++ b/xhcid/src/xhci/mod.rs
@@ -604,12 +604,14 @@ impl Xhci {
         b |= (new_max_packet_size) << 16;
         endp_ctx.b.write(b);
 
+        /*TODO: this causes issues on real hardware, maybe it should only be used on USB 2?
         let (event_trb, command_trb) = self.execute_command(|trb, cycle| {
             trb.evaluate_context(slot_id, input_context.physical(), false, cycle)
         }).await;
 
         self::scheme::handle_event_trb("EVALUATE_CONTEXT", &event_trb, &command_trb)?;
         self.event_handler_finished();
+        */
 
         Ok(())
     }
@@ -838,7 +840,7 @@ impl Xhci {
     pub fn supported_protocol_speeds(
         &self,
         port: u8,
-    ) -> Option<impl Iterator<Item = &'static ProtocolSpeed>> {
+    ) -> impl Iterator<Item = &'static ProtocolSpeed> {
         use extended::*;
         const DEFAULT_SUPP_PROTO_SPEEDS: [ProtocolSpeed; 7] = [
             // Full-speed
@@ -903,16 +905,20 @@ impl Xhci {
             ),
         ];
 
-        let supp_proto = self.supported_protocol(port)?;
-
-        Some(if supp_proto.psic() != 0 {
-            unsafe { supp_proto.protocol_speeds().iter() }
-        } else {
-            DEFAULT_SUPP_PROTO_SPEEDS.iter()
-        })
+        match self.supported_protocol(port) {
+            Some(supp_proto) => if supp_proto.psic() != 0 {
+                unsafe { supp_proto.protocol_speeds().iter() }
+            } else {
+                DEFAULT_SUPP_PROTO_SPEEDS.iter()
+            },
+            None => {
+                log::warn!("falling back to default supported protocol speeds for port {}", port);
+                DEFAULT_SUPP_PROTO_SPEEDS.iter()
+            }
+        }
     }
     pub fn lookup_psiv(&self, port: u8, psiv: u8) -> Option<&'static ProtocolSpeed> {
-        self.supported_protocol_speeds(port)?
+        self.supported_protocol_speeds(port)
             .find(|speed| speed.psiv() == psiv)
     }
 }
diff --git a/xhcid/src/xhci/scheme.rs b/xhcid/src/xhci/scheme.rs
index 0c0cf893fc..95d2315437 100644
--- a/xhcid/src/xhci/scheme.rs
+++ b/xhcid/src/xhci/scheme.rs
@@ -626,6 +626,7 @@ impl Xhci {
             let endpoints = &config_desc.interface_descs.get(usize::from(req.interface_desc.unwrap_or(0))).ok_or(Error::new(EBADFD))?.endpoints;
 
             if endpoints.len() >= 31 {
+                warn!("endpoints length {} >= 31", endpoints.len());
                 return Err(Error::new(EIO));
             }
 
@@ -644,7 +645,10 @@ impl Xhci {
         let port_speed_id = self.ports.lock().unwrap()[port].speed();
         let speed_id: &ProtocolSpeed = self
             .lookup_psiv(port as u8, port_speed_id)
-            .ok_or(Error::new(EIO))?;
+            .ok_or_else(|| {
+                warn!("no speed_id");
+                Error::new(EIO)
+            })?;
 
         {
             let port_state = self.port_states.get(&port).ok_or(Error::new(EBADFD))?;
@@ -677,7 +681,10 @@ impl Xhci {
             let mut port_state = self.port_states.get_mut(&port).ok_or(Error::new(EBADFD))?;
             let dev_desc = port_state.dev_desc.as_ref().unwrap();
             let endpoints = &dev_desc.config_descs.get(usize::from(req.config_desc)).ok_or(Error::new(EBADFD))?.interface_descs.get(usize::from(req.interface_desc.unwrap_or(0))).ok_or(Error::new(EBADFD))?.endpoints;
-            let endp_desc = endpoints.get(endp_idx as usize).ok_or(Error::new(EIO))?;
+            let endp_desc = endpoints.get(endp_idx as usize).ok_or_else(|| {
+                warn!("failed to find endpoint {}", endp_idx);
+                Error::new(EIO)
+            })?;
 
             let endp_num_xhc = Self::endp_num_to_dci(endp_num, endp_desc);
 
@@ -724,7 +731,10 @@ impl Xhci {
             // driver probably knows better. The spec says that the initial value should be 8 bytes
             // for control, 1KiB for interrupt and 3KiB for bulk and isoch.
             let avg_trb_len: u16 = match endp_desc.ty() {
-                EndpointTy::Ctrl => return Err(Error::new(EIO)), // only endpoint zero is of type control, and is configured separately with the address device command.
+                EndpointTy::Ctrl => {
+                    warn!("trying to use control endpoint");
+                    return Err(Error::new(EIO)); // only endpoint zero is of type control, and is configured separately with the address device command.
+                }
                 EndpointTy::Bulk | EndpointTy::Isoch => 3072,    // 3 KiB
                 EndpointTy::Interrupt => 1024,                   // 1 KiB
             };
@@ -778,7 +788,10 @@ impl Xhci {
             let mut input_context = port_state.input_context.lock().unwrap();
             input_context.add_context.writef(1 << endp_num_xhc, true);
 
-            let endp_ctx = input_context.device.endpoints.get_mut(endp_num_xhc as usize - 1).ok_or(Error::new(EIO))?;
+            let endp_ctx = input_context.device.endpoints.get_mut(endp_num_xhc as usize - 1).ok_or_else(|| {
+                warn!("failed to find endpoint {}", endp_num_xhc - 1);
+                Error::new(EIO)
+            })?;
 
             endp_ctx.a.write(
                 u32::from(mult) << 8