linux-kernel - [PATCH] ALSA: usb-audio: Add quirk for Focusrite Scarlett 2i2

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Message-Id: <20200420201937.12634-1-grpintar@gmail.com>
Date:   Mon, 20 Apr 2020 22:19:37 +0200
From:   Gregor Pintar <grpintar@...il.com>
To:     tiwai@...e.com, perex@...ex.cz
Cc:     linux-kernel@...r.kernel.org, alsa-devel@...a-project.org,
        grpintar@...il.com
Subject: [PATCH] ALSA: usb-audio: Add quirk for Focusrite Scarlett 2i2

Force it to use asynchronous playback.

Same quirk has already been added for Focusrite Scarlett Solo (2nd gen)
with a commit 46f5710f0b88 ("ALSA: usb-audio: Add quirk for Focusrite
Scarlett Solo").

This also seems to prevent regular clicks when playing at 44100Hz
on Scarlett 2i2 (2nd gen). I did not notice any side effects.

Signed-off-by: Gregor Pintar <grpintar@...il.com>
---
 sound/usb/quirks-table.h | 84 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)

diff --git a/sound/usb/quirks-table.h b/sound/usb/quirks-table.h
index e009d584e..bc936bf79 100644
--- a/sound/usb/quirks-table.h
+++ b/sound/usb/quirks-table.h
@@ -2840,6 +2840,90 @@ YAMAHA_DEVICE(0x7010, "UB99"),
 		}
 	}
 },
+{
+	/*
+	 * Focusrite Scarlett 2i2 2nd generation
+	 * Reports that playback should use Synch: Synchronous
+	 * while still providing a feedback endpoint. Synchronous causes
+	 * snapping on some sample rates.
+	 * Force it to use Synch: Asynchronous.
+	 */
+	USB_DEVICE(0x1235, 0x8202),
+	.driver_info = (unsigned long) &(const struct snd_usb_audio_quirk) {
+		.ifnum = QUIRK_ANY_INTERFACE,
+		.type = QUIRK_COMPOSITE,
+		.data = (const struct snd_usb_audio_quirk[]) {
+			{
+				.ifnum = 1,
+				.type = QUIRK_AUDIO_FIXED_ENDPOINT,
+				.data = &(const struct audioformat) {
+					.formats = SNDRV_PCM_FMTBIT_S32_LE,
+					.channels = 2,
+					.iface = 1,
+					.altsetting = 1,
+					.altset_idx = 1,
+					.attributes = 0,
+					.endpoint = 0x01,
+					.ep_attr = USB_ENDPOINT_XFER_ISOC |
+						USB_ENDPOINT_SYNC_ASYNC,
+					.protocol = UAC_VERSION_2,
+					.rates = SNDRV_PCM_RATE_44100 |
+						SNDRV_PCM_RATE_48000 |
+						SNDRV_PCM_RATE_88200 |
+						SNDRV_PCM_RATE_96000 |
+						SNDRV_PCM_RATE_176400 |
+						SNDRV_PCM_RATE_192000,
+					.rate_min = 44100,
+					.rate_max = 192000,
+					.nr_rates = 6,
+					.rate_table = (unsigned int[]) {
+						44100, 48000, 88200,
+						96000, 176400, 192000
+					},
+					.clock = 41
+				}
+			},
+			{
+				.ifnum = 2,
+				.type = QUIRK_AUDIO_FIXED_ENDPOINT,
+				.data = &(const struct audioformat) {
+					.formats = SNDRV_PCM_FMTBIT_S32_LE,
+					.channels = 2,
+					.iface = 2,
+					.altsetting = 1,
+					.altset_idx = 1,
+					.attributes = 0,
+					.endpoint = 0x82,
+					.ep_attr = USB_ENDPOINT_XFER_ISOC |
+						USB_ENDPOINT_SYNC_ASYNC |
+						USB_ENDPOINT_USAGE_IMPLICIT_FB,
+					.protocol = UAC_VERSION_2,
+					.rates = SNDRV_PCM_RATE_44100 |
+						SNDRV_PCM_RATE_48000 |
+						SNDRV_PCM_RATE_88200 |
+						SNDRV_PCM_RATE_96000 |
+						SNDRV_PCM_RATE_176400 |
+						SNDRV_PCM_RATE_192000,
+					.rate_min = 44100,
+					.rate_max = 192000,
+					.nr_rates = 6,
+					.rate_table = (unsigned int[]) {
+						44100, 48000, 88200,
+						96000, 176400, 192000
+					},
+					.clock = 41
+				}
+			},
+			{
+				.ifnum = 3,
+				.type = QUIRK_IGNORE_INTERFACE
+			},
+			{
+				.ifnum = -1
+			}
+		}
+	}
+},
 
 /* Access Music devices */
 {
-- 
2.20.1