Re: [PATCH] ALSA: scarlett2: Add retry on -EPROTO from scarlett2_usb_tx()

[Takashi Iwai <tiwai@suse.de>]

On Mon, 28 Jul 2025 11:30:35 +0200,
Geoffrey D. Bennett wrote:
> 
> During communication with Focusrite Scarlett Gen 2/3/4 USB audio
> interfaces, -EPROTO is sometimes returned from scarlett2_usb_tx(),
> snd_usb_ctl_msg() which can cause initialisation and control
> operations to fail intermittently.
> 
> This patch adds up to 5 retries in scarlett2_usb(), with a delay
> starting at 5ms and doubling each time. This follows the same approach
> as the fix for usb_set_interface() in endpoint.c (commit f406005e162b
> ("ALSA: usb-audio: Add retry on -EPROTO from usb_set_interface()")),
> which resolved similar -EPROTO issues during device initialisation,
> and is the same approach as in fcp.c:fcp_usb().
> 
> Fixes: 9e4d5c1be21f ("ALSA: usb-audio: Scarlett Gen 2 mixer interface")
> Closes: https://github.com/geoffreybennett/linux-fcp/issues/41
> Cc: stable@vger.kernel.org
> Signed-off-by: Geoffrey D. Bennett <g@b4.vu>

Thanks, applied now.


Takashi