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authorRuslan Bilovol <ruslan.bilovol@gmail.com>2021-03-01 13:49:31 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-03-10 09:36:12 +0100
commit789ea77310f0200c84002884ffd628e2baf3ad8a (patch)
treebd2260e76212a395f87c41532dbe571832c5cf70 /drivers/usb
parent650bf52208d804ad5ee449c58102f8dc43175573 (diff)
usb: gadget: f_uac2: always increase endpoint max_packet_size by one audio slot
As per UAC2 Audio Data Formats spec (2.3.1.1 USB Packets), if the sampling rate is a constant, the allowable variation of number of audio slots per virtual frame is +/- 1 audio slot. It means that endpoint should be able to accept/send +1 audio slot. Previous endpoint max_packet_size calculation code was adding sometimes +1 audio slot due to DIV_ROUND_UP behaviour which was rounding up to closest integer. However this doesn't work if the numbers are divisible. It had no any impact with Linux hosts which ignore this issue, but in case of more strict Windows it caused rejected enumeration Thus always add +1 audio slot to endpoint's max packet size Fixes: 913e4a90b6f9 ("usb: gadget: f_uac2: finalize wMaxPacketSize according to bandwidth") Cc: Peter Chen <peter.chen@freescale.com> Cc: <stable@vger.kernel.org> #v4.3+ Signed-off-by: Ruslan Bilovol <ruslan.bilovol@gmail.com> Link: https://lore.kernel.org/r/1614599375-8803-2-git-send-email-ruslan.bilovol@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb')
-rw-r--r--drivers/usb/gadget/function/f_uac2.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/usb/gadget/function/f_uac2.c b/drivers/usb/gadget/function/f_uac2.c
index 5d960b6603b6..6f03e944e0e3 100644
--- a/drivers/usb/gadget/function/f_uac2.c
+++ b/drivers/usb/gadget/function/f_uac2.c
@@ -478,7 +478,7 @@ static int set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
}
max_size_bw = num_channels(chmask) * ssize *
- DIV_ROUND_UP(srate, factor / (1 << (ep_desc->bInterval - 1)));
+ ((srate / (factor / (1 << (ep_desc->bInterval - 1)))) + 1);
ep_desc->wMaxPacketSize = cpu_to_le16(min_t(u16, max_size_bw,
max_size_ep));