This is a note to let you know that I've just added the patch titled

usb: gadget: f_uac2: fixed EP-IN wMaxPacketSize

to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 0560c9c552c1815e7b480bc11fd785fefc82bb27 Mon Sep 17 00:00:00 2001

From: Pavel Hofman pavel.hofman@ivitera.com Date: Fri, 24 Sep 2021 10:00:27 +0200 Subject: usb: gadget: f_uac2: fixed EP-IN wMaxPacketSize

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.

Fixes: e89bb4288378 ("usb: gadget: u_audio: add real feedback implementation") Cc: stable stable@vger.kernel.org Tested-by: Henrik Enquist henrik.enquist@gmail.com Tested-by: Jack Pham jackp@codeaurora.org Signed-off-by: Pavel Hofman pavel.hofman@ivitera.com Link: https://lore.kernel.org/r/20210924080027.5362-1-pavel.hofman@ivitera.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 be864560bfea..ef55b8bb5870 100644 --- a/drivers/usb/gadget/function/f_uac2.c +++ b/drivers/usb/gadget/function/f_uac2.c @@ -674,11 +674,17 @@ 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));