From fb8573d80676d05da4c42e5d58635dfd3428c6ed Mon Sep 17 00:00:00 2001
From: Brad Stein <Brad.Stein@gmail.com>
Date: Tue, 6 Jan 2026 05:27:27 -0300
Subject: [PATCH] uvc: use blocking event reads by default

---
 server/src/bin/lesavka-uvc.rs | 28 +++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/server/src/bin/lesavka-uvc.rs b/server/src/bin/lesavka-uvc.rs
index bdeda4e..fbf9385 100644
--- a/server/src/bin/lesavka-uvc.rs
+++ b/server/src/bin/lesavka-uvc.rs
@@ -108,6 +108,8 @@ fn main() -> Result<()> {
     let debug = env::var("LESAVKA_UVC_DEBUG").is_ok();
     let mut setup_seen: u64 = 0;
     let mut data_seen: u64 = 0;
+    let mut dq_err_seen: u64 = 0;
+    let mut dq_err_last: Option<i32> = None;
 
     loop {
         let file = open_with_retry(&dev)?;
@@ -133,6 +135,14 @@ fn main() -> Result<()> {
                 let err = std::io::Error::last_os_error();
                 match err.raw_os_error() {
                     Some(libc::EAGAIN) | Some(libc::EINTR) | Some(libc::ENOENT) => {
+                        if debug {
+                            let code = err.raw_os_error();
+                            if dq_err_seen < 10 || code != dq_err_last {
+                                eprintln!("[lesavka-uvc] dqevent idle: {err}");
+                                dq_err_seen += 1;
+                                dq_err_last = code;
+                            }
+                        }
                         thread::sleep(Duration::from_millis(10));
                         continue;
                     }
@@ -188,7 +198,11 @@ fn main() -> Result<()> {
                     }
                     handle_data(fd, uvc_send_response, &mut state, &mut pending, data);
                 }
-                _ => {}
+                _ => {
+                    if debug {
+                        eprintln!("[lesavka-uvc] event type=0x{:08x}", ev.type_);
+                    }
+                }
             }
         }
     }
@@ -255,12 +269,12 @@ impl UvcState {
 
 fn open_with_retry(path: &str) -> Result<std::fs::File> {
     for attempt in 1..=200 {
-        match OpenOptions::new()
-            .read(true)
-            .write(true)
-            .custom_flags(libc::O_NONBLOCK)
-            .open(path)
-        {
+        let mut opts = OpenOptions::new();
+        opts.read(true).write(true);
+        if env::var("LESAVKA_UVC_NONBLOCK").is_ok() {
+            opts.custom_flags(libc::O_NONBLOCK);
+        }
+        match opts.open(path) {
             Ok(f) => {
                 eprintln!("[lesavka-uvc] opened {path} (attempt {attempt})");
                 return Ok(f);