From d0f1327e768b65fb7fb47257c18073d1da7a8f8b Mon Sep 17 00:00:00 2001 From: Ruslan Bilovol Date: Mon, 1 Mar 2021 13:49:31 +0200 Subject: [PATCH] UPSTREAM: 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 Change-Id: I3bef24e77d5d9dfc11438da24664192753e2cac4 Fixes: 913e4a90b6f9 ("usb: gadget: f_uac2: finalize wMaxPacketSize according to bandwidth") Cc: Peter Chen Cc: #v4.3+ Signed-off-by: Ruslan Bilovol Link: https://lore.kernel.org/r/1614599375-8803-2-git-send-email-ruslan.bilovol@gmail.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: William Wu (cherry picked from commit 789ea77310f0200c84002884ffd628e2baf3ad8a) --- drivers/usb/gadget/function/f_uac2.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/usb/gadget/function/f_uac2.c b/drivers/usb/gadget/function/f_uac2.c index 6745361c8d4a..62cd056a911b 100644 --- a/drivers/usb/gadget/function/f_uac2.c +++ b/drivers/usb/gadget/function/f_uac2.c @@ -571,7 +571,7 @@ static int set_ep_max_packet_size(const struct f_uac_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));