diff options
| author | Geoffrey D. Bennett <g@b4.vu> | 2025-04-17 04:19:23 +0930 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-05-09 09:50:29 +0200 |
| commit | 0aaae77be5bdf819d154fa435cc07ffa31361838 (patch) | |
| tree | 1ec1fc42629117ba4b441fa4ee135c57286d75ab | |
| parent | 222b6685efe0d8c1cdb078a67bbe806f56d18f94 (diff) | |
ALSA: usb-audio: Add retry on -EPROTO from usb_set_interface()
commit f406005e162b660dc405b4f18bf7bcb93a515608 upstream.
During initialisation of Focusrite USB audio interfaces, -EPROTO is
sometimes returned from usb_set_interface(), which sometimes prevents
the device from working: subsequent usb_set_interface() and
uac_clock_source_is_valid() calls fail.
This patch adds up to 5 retries in endpoint_set_interface(), with a
delay starting at 5ms and doubling each time. 5 retries was chosen to
allow for longer than expected waits for the interface to start
responding correctly; in testing, a single 5ms delay was sufficient to
fix the issue.
Closes: https://github.com/geoffreybennett/fcp-support/issues/2
Cc: stable@vger.kernel.org
Signed-off-by: Geoffrey D. Bennett <g@b4.vu>
Link: https://patch.msgid.link/Z//7s9dKsmVxHzY2@m.b4.vu
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | sound/usb/endpoint.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c index a29f28eb7d0c6..f36ec98da4601 100644 --- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -926,6 +926,8 @@ static int endpoint_set_interface(struct snd_usb_audio *chip, { int altset = set ? ep->altsetting : 0; int err; + int retries = 0; + const int max_retries = 5; if (ep->iface_ref->altset == altset) return 0; @@ -935,8 +937,13 @@ static int endpoint_set_interface(struct snd_usb_audio *chip, usb_audio_dbg(chip, "Setting usb interface %d:%d for EP 0x%x\n", ep->iface, altset, ep->ep_num); +retry: err = usb_set_interface(chip->dev, ep->iface, altset); if (err < 0) { + if (err == -EPROTO && ++retries <= max_retries) { + msleep(5 * (1 << (retries - 1))); + goto retry; + } usb_audio_err_ratelimited( chip, "%d:%d: usb_set_interface failed (%d)\n", ep->iface, altset, err); |