4.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Peter Chen <peter.chen@xxxxxxxxxxxxx> commit 913e4a90b6f9687ac0f543e7b632753e4f51c441 upstream. According to USB Audio Device 2.0 Spec, Ch4.10.1.1: wMaxPacketSize is defined as follows: Maximum packet size this endpoint is capable of sending or receiving when this configuration is selected. This is determined by the audio bandwidth constraints of the endpoint. In current code, the wMaxPacketSize is defined as the maximum packet size for ISO endpoint, and it will let the host reserve much more space than it really needs, so that we can't let more endpoints work together at one frame. We find this issue when we try to let 4 f_uac2 gadgets work together [1] at FS connection. [1]http://www.spinics.net/lists/linux-usb/msg123478.html Acked-by: Daniel Mack <zonque@xxxxxxxxx> Cc: andrzej.p@xxxxxxxxxxx Cc: Daniel Mack <zonque@xxxxxxxxx> Cc: tiwai@xxxxxxx Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Peter Chen <peter.chen@xxxxxxxxxxxxx> Signed-off-by: Felipe Balbi <balbi@xxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/gadget/function/f_uac2.c | 31 +++++++++++++++++++++++++++++-- 1 file changed, 29 insertions(+), 2 deletions(-) --- a/drivers/usb/gadget/function/f_uac2.c +++ b/drivers/usb/gadget/function/f_uac2.c @@ -975,6 +975,29 @@ free_ep(struct uac2_rtd_params *prm, str "%s:%d Error!\n", __func__, __LINE__); } +static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts, + struct usb_endpoint_descriptor *ep_desc, + unsigned int factor, bool is_playback) +{ + int chmask, srate, ssize; + u16 max_packet_size; + + if (is_playback) { + chmask = uac2_opts->p_chmask; + srate = uac2_opts->p_srate; + ssize = uac2_opts->p_ssize; + } else { + chmask = uac2_opts->c_chmask; + srate = uac2_opts->c_srate; + ssize = uac2_opts->c_ssize; + } + + max_packet_size = num_channels(chmask) * ssize * + DIV_ROUND_UP(srate, factor / (1 << (ep_desc->bInterval - 1))); + ep_desc->wMaxPacketSize = cpu_to_le16(min(max_packet_size, + le16_to_cpu(ep_desc->wMaxPacketSize))); +} + static int afunc_bind(struct usb_configuration *cfg, struct usb_function *fn) { @@ -1070,10 +1093,14 @@ afunc_bind(struct usb_configuration *cfg uac2->p_prm.uac2 = uac2; uac2->c_prm.uac2 = uac2; + /* Calculate wMaxPacketSize according to audio bandwidth */ + set_ep_max_packet_size(uac2_opts, &fs_epin_desc, 1000, true); + set_ep_max_packet_size(uac2_opts, &fs_epout_desc, 1000, false); + set_ep_max_packet_size(uac2_opts, &hs_epin_desc, 8000, true); + set_ep_max_packet_size(uac2_opts, &hs_epout_desc, 8000, false); + hs_epout_desc.bEndpointAddress = fs_epout_desc.bEndpointAddress; - hs_epout_desc.wMaxPacketSize = fs_epout_desc.wMaxPacketSize; hs_epin_desc.bEndpointAddress = fs_epin_desc.bEndpointAddress; - hs_epin_desc.wMaxPacketSize = fs_epin_desc.wMaxPacketSize; ret = usb_assign_descriptors(fn, fs_audio_desc, hs_audio_desc, NULL); if (ret) -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html