ALSA: usb-audio: Allow Focusrite devices to use low samplerates

JIRA: https://issues.redhat.com/browse/RHEL-112755

commit cc8e910
Author: Tina Wuest <tina@wuest.me>
Date: Mon Sep 1 12:20:24 2025 +0300

    ALSA: usb-audio: Allow Focusrite devices to use low samplerates

    Commit 05f254a ("ALSA: usb-audio:
    Improve filtering of sample rates on Focusrite devices") changed the
    check for max_rate in a way which was overly restrictive, forcing
    devices to use very high samplerates if they support them, despite
    support existing for lower rates as well.

    This maintains the intended outcome (ensuring samplerates selected are
    supported) while allowing devices with higher maximum samplerates to be
    opened at all supported samplerates.

    This patch was tested with a Clarett+ 8Pre USB

    Fixes: 05f254a ("ALSA: usb-audio: Improve filtering of sample rates on Focusrite devices")
    Signed-off-by: Tina Wuest <tina@wuest.me>
    Link: https://patch.msgid.link/20250901092024.140993-1-tina@wuest.me
    Signed-off-by: Takashi Iwai <tiwai@suse.de>

Signed-off-by: Jaroslav Kysela <jkysela@redhat.com>

Author: jkysela-rh

sound/usb/format.c

@@ -327,12 +327,16 @@ static bool focusrite_valid_sample_rate(struct snd_usb_audio *chip,
 		max_rate = combine_quad(&fmt[6]);
 
 		switch (max_rate) {
+		case 192000:
+			if (rate == 176400 || rate == 192000)
+				return true;
+			fallthrough;
+		case 96000:
+			if (rate == 88200 || rate == 96000)
+				return true;
+			fallthrough;
 		case 48000:
 			return (rate == 44100 || rate == 48000);
-		case 96000:
-			return (rate == 88200 || rate == 96000);
-		case 192000:
-			return (rate == 176400 || rate == 192000);
 		default:
 			usb_audio_info(chip,
 				"%u:%d : unexpected max rate: %u\n",