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From:   Arvind Sankar <nivedita@alum.mit.edu>
To:     Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.com>
Cc:     alsa-devel@alsa-project.org, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH] ALSA: usb-audio: Apply sample rate quirk for Audioengine D1
Date:   Tue, 11 Feb 2020 11:22:35 -0500
Message-Id: <20200211162235.1639889-1-nivedita@alum.mit.edu>
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Sender: linux-kernel-owner@vger.kernel.org
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The Audioengine D1 (0x2912:0x30c8) does support reading the sample rate,
but it returns the rate in byte-reversed order.

When setting sampling rate, the driver produces these warning messages:
[168840.944226] usb 3-2.2: current rate 4500480 is different from the runtime rate 44100
[168854.930414] usb 3-2.2: current rate 8436480 is different from the runtime rate 48000
[168905.185825] usb 3-2.1.2: current rate 30465 is different from the runtime rate 96000

As can be seen from the hexadecimal conversion, the current rate read
back is byte-reversed from the rate that was set.

44100 == 0x00ac44, 4500480 == 0x44ac00
48000 == 0x00bb80, 8436480 == 0x80bb00
96000 == 0x017700,   30465 == 0x007701

Rather than implementing a new quirk to reverse the order, just skip
checking the rate to avoid spamming the log.

Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
---
 sound/usb/quirks.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index 3a5242e383b2..7f558f4b4520 100644
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -1440,6 +1440,7 @@ bool snd_usb_get_sample_rate_quirk(struct snd_usb_audio *chip)
 	case USB_ID(0x1395, 0x740a): /* Sennheiser DECT */
 	case USB_ID(0x1901, 0x0191): /* GE B850V3 CP2114 audio interface */
 	case USB_ID(0x21b4, 0x0081): /* AudioQuest DragonFly */
+	case USB_ID(0x2912, 0x30c8): /* Audioengine D1 */
 		return true;
 	}
 
-- 
2.24.1