From ee27e07bf394cab81bcebd9a09a6404b53db1220 Mon Sep 17 00:00:00 2001
From: puddly <32534428+puddly@users.noreply.github.com>
Date: Thu, 22 Oct 2026 17:44:34 +0000
Subject: [PATCH 1/3] Ignore `EPERM` when setting low latency

---
 serialx/platforms/serial_linux.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/serialx/platforms/serial_linux.py b/serialx/platforms/serial_linux.py
index 8f08d09..b8ac83f 100644
--- a/serialx/platforms/serial_linux.py
+++ b/serialx/platforms/serial_linux.py
@@ -304,6 +304,8 @@ def _after_configure_port(self) -> None:
             except OSError as exc:
                 if exc.errno in (errno.ENOTTY, errno.EOPNOTSUPP):
                     LOGGER.debug("Device does not support setting low latency")
+                elif exc.errno == errno.EPERM:
+                    LOGGER.debug("User does not have permission to set low latency")
                 else:
                     raise
 

From 7986f83fbd95db369804a9663e6b83260ee90ab7 Mon Sep 17 00:00:00 2001
From: puddly <32534428+puddly@users.noreply.github.com>
Date: Thu, 22 Oct 2026 17:53:23 +0000
Subject: [PATCH 2/3] Add a test

---
 tests/test_serial_linux.py | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/tests/test_serial_linux.py b/tests/test_serial_linux.py
index 0a053e8..2da45a0 100644
--- a/tests/test_serial_linux.py
+++ b/tests/test_serial_linux.py
@@ -4,7 +4,7 @@
 
 import pytest
 
-if sys.platform != "linux":
+if sys.platform not in ("linux", "darwin"):
     pytest.skip("Linux-only tests", allow_module_level=True)
 
 import asyncio
@@ -101,15 +101,23 @@ def test_set_non_posix_baudrate_zero_speed_raises() -> None:
     assert captured == []
 
 
+@pytest.mark.parametrize(
+    "err",
+    [
+        OSError(errno.EOPNOTSUPP, "Not supported"),
+        OSError(errno.ENOTTY, "Inappropriate ioctl for device"),
+        OSError(errno.EPERM, "Operation not permitted"),
+    ],
+)
 @patch("serialx.platforms.serial_linux.TIOCGSERIAL", TIOCGSERIAL)
 @patch("serialx.platforms.serial_linux.TIOCSSERIAL", TIOCSSERIAL)
-def test_tiocgserial_ioctl_not_supported() -> None:
+def test_tiocgserial_ioctl_not_supported(err: OSError) -> None:
     """Test that TIOCGSERIAL ioctl not supported is handled gracefully."""
     ioctl_orig = fcntl.ioctl
 
     def ioctl(fd: int, request: int, arg: Any = 0, mutate_flag: bool = True) -> Any:
         if request in (TIOCGSERIAL, TIOCSSERIAL):
-            raise OSError(errno.EOPNOTSUPP, "Not supported")
+            raise err
 
         return ioctl_orig(fd, request, arg, mutate_flag)
 

From 0cfd7a562c6857bf9dbfbfa55319319ecae6426e Mon Sep 17 00:00:00 2001
From: puddly <32534428+puddly@users.noreply.github.com>
Date: Thu, 22 Oct 2026 18:24:48 +0000
Subject: [PATCH 3/3] Swap back to Linux-only tests

---
 tests/test_serial_linux.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/test_serial_linux.py b/tests/test_serial_linux.py
index 2da45a0..fd7428c 100644
--- a/tests/test_serial_linux.py
+++ b/tests/test_serial_linux.py
@@ -4,7 +4,7 @@
 
 import pytest
 
-if sys.platform not in ("linux", "darwin"):
+if sys.platform != "linux":
     pytest.skip("Linux-only tests", allow_module_level=True)
 
 import asyncio