linux/Documentation/ABI/testing/configfs-usb-gadget-uac2
Pavel Hofman 355a05dc83 usb: gadget: f_uac2: Optionally determine bInterval for HS and SS
Allow setting configfs params p_hs_bint/c_hs_bint to 0. If they are set
to 0, determine the largest bInterval (4 to 1) for which the required
bandwidth of the max samplerate fits the max allowed packet size. If the
required bandwidth exceeds max bandwidth for single-packet mode
(ep->mc=1), keep bInterval at 1.

The FS speed is left at fixed bInterval=1.

If for any speed the required bandwidth exceeds the max bandwidth
corresponding to the selected/determined bInterval, print a warning.

Signed-off-by: Pavel Hofman <pavel.hofman@ivitera.com>
Link: https://lore.kernel.org/r/20220127114331.41367-4-pavel.hofman@ivitera.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-01-31 14:26:18 +01:00

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What: /config/usb-gadget/gadget/functions/uac2.name
Date: Sep 2014
KernelVersion: 3.18
Description:
The attributes:
===================== =======================================
c_chmask capture channel mask
c_srate list of capture sampling rates (comma-separated)
c_ssize capture sample size (bytes)
c_hs_bint capture bInterval for HS/SS (1-4: fixed, 0: auto)
c_sync capture synchronization type
(async/adaptive)
c_mute_present capture mute control enable
c_volume_present capture volume control enable
c_volume_min capture volume control min value
(in 1/256 dB)
c_volume_max capture volume control max value
(in 1/256 dB)
c_volume_res capture volume control resolution
(in 1/256 dB)
fb_max maximum extra bandwidth in async mode
p_chmask playback channel mask
p_srate list of playback sampling rates (comma-separated)
p_ssize playback sample size (bytes)
p_hs_bint playback bInterval for HS/SS (1-4: fixed, 0: auto)
p_mute_present playback mute control enable
p_volume_present playback volume control enable
p_volume_min playback volume control min value
(in 1/256 dB)
p_volume_max playback volume control max value
(in 1/256 dB)
p_volume_res playback volume control resolution
(in 1/256 dB)
req_number the number of pre-allocated requests
for both capture and playback
function_name name of the interface
===================== =======================================