From c53bb7394a20e180e2ac7e81cc468025018bd1da Mon Sep 17 00:00:00 2001
From: alexmoon <alex.r.moon@gmail.com>
Date: Mon, 28 Mar 2022 20:10:13 -0400
Subject: [PATCH] Switch to ControlHandler owned bufs for control_in()

---
 embassy-usb/src/control.rs          |  7 +++----
 embassy-usb/src/lib.rs              | 11 ++++-------
 examples/nrf/src/bin/usb/cdc_acm.rs | 14 ++++++++------
 3 files changed, 15 insertions(+), 17 deletions(-)

diff --git a/embassy-usb/src/control.rs b/embassy-usb/src/control.rs
index cdae2d97..195b218d 100644
--- a/embassy-usb/src/control.rs
+++ b/embassy-usb/src/control.rs
@@ -133,8 +133,8 @@ pub enum OutResponse {
 
 #[derive(Copy, Clone, Eq, PartialEq, Debug)]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
-pub enum InResponse {
-    Accepted(usize),
+pub enum InResponse<'a> {
+    Accepted(&'a [u8]),
     Rejected,
 }
 
@@ -164,8 +164,7 @@ pub trait ControlHandler {
     /// # Arguments
     ///
     /// * `req` - The request from the SETUP packet.
-    /// * `resp` - The buffer for you to write the response.
-    fn control_in(&mut self, req: Request, resp: &mut [u8]) -> InResponse {
+    fn control_in(&mut self, req: Request) -> InResponse<'_> {
         InResponse::Rejected
     }
 }
diff --git a/embassy-usb/src/lib.rs b/embassy-usb/src/lib.rs
index 9ac55db7..5a82f5ca 100644
--- a/embassy-usb/src/lib.rs
+++ b/embassy-usb/src/lib.rs
@@ -284,13 +284,10 @@ impl<'d, D: Driver<'d>> UsbDevice<'d, D> {
                     .find(|(i, _)| req.index == *i as _)
                     .map(|(_, h)| h);
                 match handler {
-                    Some(handler) => {
-                        let mut buf = [0; 128];
-                        match handler.control_in(req, &mut buf) {
-                            InResponse::Accepted(len) => self.control.accept_in(&buf[..len]).await,
-                            InResponse::Rejected => self.control.reject(),
-                        }
-                    }
+                    Some(handler) => match handler.control_in(req) {
+                        InResponse::Accepted(data) => self.control.accept_in(data).await,
+                        InResponse::Rejected => self.control.reject(),
+                    },
                     None => self.control.reject(),
                 }
             }
diff --git a/examples/nrf/src/bin/usb/cdc_acm.rs b/examples/nrf/src/bin/usb/cdc_acm.rs
index 4b492593..2a78324f 100644
--- a/examples/nrf/src/bin/usb/cdc_acm.rs
+++ b/examples/nrf/src/bin/usb/cdc_acm.rs
@@ -66,6 +66,7 @@ pub struct CdcAcmClass<'d, D: Driver<'d>> {
 
 struct Control<'a> {
     shared: &'a ControlShared,
+    buf: [u8; 7],
 }
 
 /// Shared data between Control and CdcAcmClass
@@ -138,17 +139,17 @@ impl<'a> ControlHandler for Control<'a> {
         }
     }
 
-    fn control_in(&mut self, req: Request, resp: &mut [u8]) -> InResponse {
+    fn control_in(&mut self, req: Request) -> InResponse<'_> {
         match req.request {
             // REQ_GET_ENCAPSULATED_COMMAND is not really supported - it will be rejected below.
             REQ_GET_LINE_CODING if req.length == 7 => {
                 info!("Sending line coding");
                 let coding = self.shared().line_coding.lock(|x| x.get());
-                resp[0..4].copy_from_slice(&coding.data_rate.to_le_bytes());
-                resp[4] = coding.stop_bits as u8;
-                resp[5] = coding.parity_type as u8;
-                resp[6] = coding.data_bits;
-                InResponse::Accepted(7)
+                self.buf[0..4].copy_from_slice(&coding.data_rate.to_le_bytes());
+                self.buf[4] = coding.stop_bits as u8;
+                self.buf[5] = coding.parity_type as u8;
+                self.buf[6] = coding.data_bits;
+                InResponse::Accepted(&self.buf)
             }
             _ => InResponse::Rejected,
         }
@@ -165,6 +166,7 @@ impl<'d, D: Driver<'d>> CdcAcmClass<'d, D> {
     ) -> Self {
         let control = state.control.write(Control {
             shared: &state.shared,
+            buf: [0; 7],
         });
 
         let control_shared = &state.shared;