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FROMLIST: usb: gadget: f_uac2: fixed EP-IN wMaxPacketSize

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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@ivitera.com>
Tested-by: Henrik Enquist <henrik.enquist@gmail.com>
Tested-by: Jack Pham <jackp@codeaurora.org>
Bug: 199044440
Link: https://lore.kernel.org/linux-usb/b11414f0-1783-192e-2b79-066dd4c814d0@ivitera.com/
Change-Id: I74994d717b0eb543104e3ed7b20ca06c7c584be9
Signed-off-by: Jack Pham <jackp@codeaurora.org>
This commit is contained in:
Pavel Hofman 2021-09-06 14:04:00 +02:00 committed by Greg Kroah-Hartman
parent ab9ceb4334
commit 3f26745cae
1 changed files with 10 additions and 4 deletions
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14
drivers/usb/gadget/function/f_uac2.c
View File

@ -585,11 +585,17 @@ 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));