6.12-stable review patch. If anyone has any objections, please let me know.
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From: Geoffrey D. Bennett g@b4.vu
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 --- sound/usb/endpoint.c | 7 +++++++ 1 file changed, 7 insertions(+)
--- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -926,6 +926,8 @@ static int endpoint_set_interface(struct { 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
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);