From: Chris Wulff <crwu...@gmail.com>

[ Upstream commit 55f7326170d9e83e2d828591938e1101982a679c ]

Create a quirk that allows special processing and/or
skipping the call to snd_card_register.

For HyperX AMP, which uses two interfaces, but only has
a capture stream in the second, this allows the capture
stream to merge with the first PCM.

Signed-off-by: Chris Wulff <crwu...@gmail.com>
Link: https://lore.kernel.org/r/20200314165449.4086-3-crwu...@gmail.com
Signed-off-by: Takashi Iwai <ti...@suse.de>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 sound/usb/card.c   | 12 ++++++++----
 sound/usb/quirks.c | 14 ++++++++++++++
 sound/usb/quirks.h |  3 +++
 3 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/sound/usb/card.c b/sound/usb/card.c
index f9a64e9526f54..2284377cbb98d 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -659,10 +659,14 @@ static int usb_audio_probe(struct usb_interface *intf,
                        goto __error;
        }
 
-       /* we are allowed to call snd_card_register() many times */
-       err = snd_card_register(chip->card);
-       if (err < 0)
-               goto __error;
+       /* we are allowed to call snd_card_register() many times, but first
+        * check to see if a device needs to skip it or do anything special
+        */
+       if (snd_usb_registration_quirk(chip, ifnum) == 0) {
+               err = snd_card_register(chip->card);
+               if (err < 0)
+                       goto __error;
+       }
 
        if (quirk && quirk->shares_media_device) {
                /* don't want to fail when snd_media_device_create() fails */
diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index 9d11ff742e5f5..f3e26e65c3257 100644
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -1782,3 +1782,17 @@ void snd_usb_audioformat_attributes_quirk(struct 
snd_usb_audio *chip,
                break;
        }
 }
+
+int snd_usb_registration_quirk(struct snd_usb_audio *chip,
+                              int iface)
+{
+       switch (chip->usb_id) {
+       case USB_ID(0x0951, 0x16d8): /* Kingston HyperX AMP */
+               /* Register only when we reach interface 2 so that streams can
+                * merge correctly into PCMs from interface 0
+                */
+               return (iface != 2);
+       }
+       /* Register as normal */
+       return 0;
+}
diff --git a/sound/usb/quirks.h b/sound/usb/quirks.h
index df0355843a4c1..3afc01eabc7e2 100644
--- a/sound/usb/quirks.h
+++ b/sound/usb/quirks.h
@@ -51,4 +51,7 @@ void snd_usb_audioformat_attributes_quirk(struct 
snd_usb_audio *chip,
                                          struct audioformat *fp,
                                          int stream);
 
+int snd_usb_registration_quirk(struct snd_usb_audio *chip,
+                              int iface);
+
 #endif /* __USBAUDIO_QUIRKS_H */
-- 
2.25.1



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