Async feedback patches broke enumeration on Windows 10 previously fixed
by commit 789ea77310f0 ("usb: gadget: f_uac2: always increase endpoint
max_packet_size by one audio slot").
While the existing calculation for EP OUT capture for async mode yields
size+1 frame due to uac2_opts->fb_max > 0, playback side lost the +1
feature. Therefore the +1 frame addition must be re-introduced for
playback. Win10 enumerates the device only when both EP IN and EP OUT
max packet sizes are (at least) +1 frame.
Signed-off-by: Pavel Hofman <pavel.hofman@xxxxxxxxxxx>
Fixes: e89bb4288378 ("usb: gadget: u_audio: add real feedback
implementation")
Cc: stable@xxxxxxxxxxxxxxx
Tested-by: Henrik Enquist <henrik.enquist@xxxxxxxxx>
Tested-by: Jack Pham <jackp@xxxxxxxxxxxxxx>
---
drivers/usb/gadget/function/f_uac2.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/gadget/function/f_uac2.c b/drivers/usb/gadget/function/f_uac2.c
index 17a7ab2c799c..5c7eddf511e5 100644
--- a/drivers/usb/gadget/function/f_uac2.c
+++ b/drivers/usb/gadget/function/f_uac2.c
@@ -665,11 +665,17 @@ static int set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
ssize = uac2_opts->c_ssize;
}
- if (!is_playback && (uac2_opts->c_sync == USB_ENDPOINT_SYNC_ASYNC))
+ if (!is_playback && (uac2_opts->c_sync == USB_ENDPOINT_SYNC_ASYNC)) {
+ // Win10 requires max packet size + 1 frame
srate = srate * (1000 + uac2_opts->fb_max) / 1000;
-
- max_size_bw = num_channels(chmask) * ssize *
- DIV_ROUND_UP(srate, factor / (1 << (ep_desc->bInterval - 1)));
+ // updated srate is always bigger, therefore DIV_ROUND_UP always yields +1
+ max_size_bw = num_channels(chmask) * ssize *
+ (DIV_ROUND_UP(srate, factor / (1 << (ep_desc->bInterval - 1))));
+ } else {
+ // adding 1 frame provision for Win10
+ max_size_bw = num_channels(chmask) * ssize *
+ (DIV_ROUND_UP(srate, factor / (1 << (ep_desc->bInterval - 1))) + 1);
+ }
ep_desc->wMaxPacketSize = cpu_to_le16(min_t(u16, max_size_bw,
max_size_ep));
--
2.25.1
