diff --git a/src/context/mod.rs b/src/context/mod.rs
index fda71065..8c04fd3d 100644
--- a/src/context/mod.rs
+++ b/src/context/mod.rs
@@ -77,6 +77,12 @@ impl<const N: usize> Input<N> {
             device: Device::new(),
         }
     }
+
+    /// copy output ctx to input
+    /// refer linux code
+    pub fn copy_from_output(&mut self, out_ctx: &Device<N>) {
+        self.device = out_ctx.clone()
+    }
 }
 impl<const N: usize> InputHandler for Input<N> {
     fn control(&self) -> &dyn InputControlHandler {
@@ -216,6 +222,16 @@ pub trait InputControlHandler: AsRef<[u32]> + AsMut<[u32]> {
         self.as_mut()[1].set_bit(i, false);
     }
 
+    /// clear all add flag expect ep 0
+    fn clear_all_nonep0_add_flag(&mut self) {
+        self.as_mut()[1] = 1u32;
+    }
+
+    /// clear all drop flag
+    fn clear_all_drop_flag(&mut self) {
+        self.as_mut()[0] = 0u32;
+    }
+
     rw_field_cx!([7](0..=7), configuration_value, "Configuration Value", u8);
     rw_field_cx!([7](8..=15), interface_number, "Interface Number", u8);
     rw_field_cx!([7](16..=23), alternate_setting, "Alternate Setting", u8);
@@ -283,6 +299,10 @@ impl<const N: usize> DeviceHandler for Device<N> {
 
         &mut self.endpoints[dci - 1]
     }
+
+    fn fill_endpoints_with_0(&mut self) {
+        self.endpoints.fill(Endpoint::new())
+    }
 }
 
 /// A trait to handle Device Context.
@@ -308,6 +328,9 @@ pub trait DeviceHandler {
     /// This method panics if `dci > 31 || dci == 0`. Call [`DeviceHandler::slot_mut`] if you want
     /// a mutable handler of Slot Context.
     fn endpoint_mut(&mut self, dci: usize) -> &mut dyn EndpointHandler;
+
+    /// fill all endpoints with 0
+    fn fill_endpoints_with_0(&mut self);
 }
 
 /// Slot Context.
diff --git a/src/lib.rs b/src/lib.rs
index a64afa08..bd8e4e98 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -55,7 +55,6 @@
     unused_import_braces,
     unused_lifetimes,
     unused_qualifications,
-    pointer_structural_match,
     missing_debug_implementations
 )]
 #![allow(clippy::missing_panics_doc)]
diff --git a/src/registers/mod.rs b/src/registers/mod.rs
index b192dbd7..53f436f3 100644
--- a/src/registers/mod.rs
+++ b/src/registers/mod.rs
@@ -76,7 +76,7 @@ where
     /// ```
     pub unsafe fn new(mmio_base: usize, mapper: M) -> Self {
         let capability = Capability::new(mmio_base, &mapper);
-        let doorbell = doorbell::Doorbell::new(mmio_base, &capability, mapper.clone());
+        let doorbell = Doorbell::new(mmio_base, &capability, mapper.clone());
         let operational =
             Operational::new(mmio_base, capability.caplength.read_volatile(), &mapper);
         let port_register_set = PortRegisterSet::new(mmio_base, &capability, mapper.clone());