ALSA: usb-audio: Rewrite registration quirk handling

A slight refactoring of the registration quirk code.  Now it uses the
table lookup for easy additions in future.  Also the return type was
changed to bool, and got a few more comments.

Link: https://lore.kernel.org/r/20200325103322.2508-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/card.c b/sound/usb/card.c
index 16bbe2a..55d563a 100644 (file)
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -665,7 +665,7 @@ static int usb_audio_probe(struct usb_interface *intf,
        /* 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) {
+       if (!snd_usb_registration_quirk(chip, ifnum)) {
                err = snd_card_register(chip->card);
                if (err < 0)
                        goto __error;

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index d605aff..86f192a 100644 (file)
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -1809,16 +1809,36 @@ void snd_usb_audioformat_attributes_quirk(struct snd_usb_audio *chip,
        }
 }
 
-int snd_usb_registration_quirk(struct snd_usb_audio *chip,
-                              int iface)
+/*
+ * registration quirk:
+ * the registration is skipped if a device matches with the given ID,
+ * unless the interface reaches to the defined one.  This is for delaying
+ * the registration until the last known interface, so that the card and
+ * devices appear at the same time.
+ */
+
+struct registration_quirk {
+       unsigned int usb_id;    /* composed via USB_ID() */
+       unsigned int interface; /* the interface to trigger register */
+};
+
+#define REG_QUIRK_ENTRY(vendor, product, iface) \
+       { .usb_id = USB_ID(vendor, product), .interface = (iface) }
+
+static const struct registration_quirk registration_quirks[] = {
+       REG_QUIRK_ENTRY(0x0951, 0x16d8, 2),     /* Kingston HyperX AMP */
+       { 0 }                                   /* terminator */
+};
+
+/* return true if skipping registration */
+bool 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);
-       }
+       const struct registration_quirk *q;
+
+       for (q = registration_quirks; q->usb_id; q++)
+               if (chip->usb_id == q->usb_id)
+                       return iface != q->interface;
+
        /* Register as normal */
-       return 0;
+       return false;
 }

diff --git a/sound/usb/quirks.h b/sound/usb/quirks.h
index 3afc01e..c76cf24 100644 (file)
--- a/sound/usb/quirks.h
+++ b/sound/usb/quirks.h
@@ -51,7 +51,6 @@ 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);
+bool snd_usb_registration_quirk(struct snd_usb_audio *chip, int iface);
 
 #endif /* __USBAUDIO_QUIRKS_H */