[PATCHv2 0/3] USB Audio Gadget: Support multiple sampling rates

[Julian Scheel]

Sending v2 of this patch series, including fixes for build regressions
introduced with the original series. I missed the usage of f_uac* in the
legacy modules and did not test that. Fixed now, see patches changelog for
details.

This patch series adds support for exposing multiple supported sampling rates
from UAC1 and UAC2 USB gadgets to the connected host. It is currently limited
to up to ten discrete sampling frequencies. The USB specification does not
actually limit this, but to avoid complex list handling I am using a static
array for now.
As the configfs bindings for f_uac1 and f_uac2 have been identical already, I
decided to move the shared code for this out of the functions first. This
avoids code duplication and simplifies the addition of the list parsing for
sampling rates.
The host can configure active sampling rate and the function adapts it's
internal active rate automatically. On playback/capture start the rate is
checked, so that the user recognizes rate mismatches. Furthermore the active
rate is exposed as an amixer control with change notifications, so that
users can check current rate upfront and get notified about updates.

Julian Scheel (3):
  usb: gadget: f_uac1: Fix endpoint reading
  usb: gadget: f_uac*: Reduce code duplication
  usb: gadget: f_uac*: Support multiple sampling rates

 Documentation/ABI/testing/configfs-usb-gadget-uac1 |   4 +-
 Documentation/usb/gadget-testing.txt               |   8 +-
 drivers/usb/gadget/function/f_uac1.c               | 258 +++++++++---------
 drivers/usb/gadget/function/f_uac2.c               | 297 ++++++++++-----------
 drivers/usb/gadget/function/u_audio.c              | 118 +++++++-
 drivers/usb/gadget/function/u_audio.h              |   9 +-
 drivers/usb/gadget/function/u_uac.h                | 180 +++++++++++++
 drivers/usb/gadget/function/u_uac1.h               |  41 ---
 drivers/usb/gadget/function/u_uac2.h               |  44 ---
 drivers/usb/gadget/legacy/audio.c                  |  91 ++-----
 10 files changed, 608 insertions(+), 442 deletions(-)
 create mode 100644 drivers/usb/gadget/function/u_uac.h
 delete mode 100644 drivers/usb/gadget/function/u_uac1.h
 delete mode 100644 drivers/usb/gadget/function/u_uac2.h

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2.13.2