ALSA: usb-audio: Simplify with usb_endpoint_max_periodic_payload()

Recently we received a new helper function,
usb_endpoint_max_periodic_payload(), for calculating the max packet
size for periodic transfer.

Simplify the former open code with the new helper function.

Fixes: a748e1dbb2df ("ALSA: usb-audio: Fix max bytes-per-interval calculation")
Suggested-by: Michal Pecio <michal.pecio@gmail.com>
Link: https://lore.kernel.org/20251124210518.90054-1-dylan_robinson@motu.com
Link: https://patch.msgid.link/20251202070828.145656-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/stream.c b/sound/usb/stream.c
index 074a61215de6b27588b95bf8fffbebcecd82e9b7..ec7d756d78d178d62638e7604fdf94f19e0cc914 100644 (file)
--- a/sound/usb/stream.c
+++ b/sound/usb/stream.c
@@ -684,43 +684,13 @@ snd_usb_find_output_terminal_descriptor(struct usb_host_interface *ctrl_iface,
        return NULL;
 }
 
-static unsigned int
-snd_usb_max_bytes_per_interval(struct snd_usb_audio *chip,
-                                       struct usb_host_interface *alts)
-{
-       struct usb_host_endpoint *ep = &alts->endpoint[0];
-       unsigned int max_bytes = usb_endpoint_maxp(&ep->desc);
-
-       /* SuperSpeed isoc endpoints have up to 16 bursts of up to 3 packets each */
-       if (snd_usb_get_speed(chip->dev) >= USB_SPEED_SUPER) {
-               int burst = 1 + ep->ss_ep_comp.bMaxBurst;
-               int mult = USB_SS_MULT(ep->ss_ep_comp.bmAttributes);
-               max_bytes *= burst;
-               max_bytes *= mult;
-       }
-
-       if (snd_usb_get_speed(chip->dev) == USB_SPEED_SUPER_PLUS &&
-               USB_SS_SSP_ISOC_COMP(ep->ss_ep_comp.bmAttributes)) {
-               max_bytes = le32_to_cpu(ep->ssp_isoc_ep_comp.dwBytesPerInterval);
-       }
-
-       /* High speed, 1-3 packets/uframe, max 6 for eUSB2 double bw */
-       if (snd_usb_get_speed(chip->dev) == USB_SPEED_HIGH) {
-               if (usb_endpoint_is_hs_isoc_double(chip->dev, ep))
-                       max_bytes = le32_to_cpu(ep->eusb2_isoc_ep_comp.dwBytesPerInterval);
-               else
-                       max_bytes *= usb_endpoint_maxp_mult(&ep->desc);
-       }
-
-       return max_bytes;
-}
-
 static struct audioformat *
 audio_format_alloc_init(struct snd_usb_audio *chip,
                       struct usb_host_interface *alts,
                       int protocol, int iface_no, int altset_idx,
                       int altno, int num_channels, int clock)
 {
+       struct usb_host_endpoint *ep = &alts->endpoint[0];
        struct audioformat *fp;
 
        fp = kzalloc(sizeof(*fp), GFP_KERNEL);
@@ -734,7 +704,7 @@ audio_format_alloc_init(struct snd_usb_audio *chip,
        fp->ep_attr = get_endpoint(alts, 0)->bmAttributes;
        fp->datainterval = snd_usb_parse_datainterval(chip, alts);
        fp->protocol = protocol;
-       fp->maxpacksize = snd_usb_max_bytes_per_interval(chip, alts);
+       fp->maxpacksize = usb_endpoint_max_periodic_payload(chip->dev, ep);
        fp->channels = num_channels;
        fp->clock = clock;
        INIT_LIST_HEAD(&fp->list);