Re: [PATCH 00/18] RFC: Remove deprecated audio features

[Mark Cave-Ayland]

On 25/04/2022 09:21, Martin Kletzander wrote:

> I wanted to deal with https://bugzilla.redhat.com/2043498 and I got a
> suggesstion that removing deprecated features could actually make it
> easier to propagate the error.  In the end (last patch) it turns out the
> error is still just reported with error_fatal, so it probably is not
> really needed, but I really wanted to dig into QEMU more and learn some
> of the internals for quite some time now.  So I used the opportunity.
> The one-liner ended up being an 18 patch series which was, for someone
> who has just one commit in QEMU codebase, a pretty challenging task.
> Although I tried my best to do things properly, I am not sure whether I
> handled everything correctly, hence the RFC.
>
> Any comments are very much appreciated.  Thanks and have a nice day ;)
>
> Martin Kletzander (18):
>    hw/audio: Remove -soundhw support
>    hw/input/tsc210x: Extract common init code into new function
>    hw/audio: Simplify hda audio init
>    hw/audio/lm4549: Add errp error reporting to init function
>    tests/qtest: Specify audiodev= and -audiodev
>    ui/vnc: Require audiodev=
>    Introduce machine's default-audiodev property
>    audio: Add easy dummy audio initialiser
>    hw/display/xlnx_dp.c: Add audiodev property
>    hw/input/tsc210x.c: Support machine-default audiodev with fallback
>    hw/arm: Support machine-default audiodev with fallback
>    hw/ppc: Support machine-default audiodev with fallback
>    audio: Make AUD_register_card fallible and require audiodev=
>    audio: Require AudioState in AUD_add_capture
>    audio: Be more strict during audio backend initialisation
>    audio: Remove legacy audio environment variables and options
>    audio: Remove unused can_be_default
>    audio/spiceaudio: Fail initialisation when not using spice
>
>   audio/alsaaudio.c                             |   1 -
>   audio/audio.c                                 | 204 +++----
>   audio/audio.h                                 |   5 +-
>   audio/audio_int.h                             |   1 -
>   audio/audio_legacy.c                          | 555 ------------------
>   audio/coreaudio.m                             |   1 -
>   audio/dbusaudio.c                             |   1 -
>   audio/dsoundaudio.c                           |   1 -
>   audio/jackaudio.c                             |   1 -
>   audio/meson.build                             |   1 -
>   audio/noaudio.c                               |   1 -
>   audio/ossaudio.c                              |   1 -
>   audio/paaudio.c                               |   1 -
>   audio/sdlaudio.c                              |   1 -
>   audio/spiceaudio.c                            |   3 +-
>   audio/wavaudio.c                              |   1 -
>   docs/about/deprecated.rst                     |  24 -
>   docs/about/removed-features.rst               |  27 +
>   docs/qdev-device-use.txt                      |  21 +-
>   docs/replay.txt                               |   2 +-
>   hw/arm/integratorcp.c                         |   8 +-
>   hw/arm/musicpal.c                             |   8 +-
>   hw/arm/omap2.c                                |  11 +-
>   hw/arm/realview.c                             |   3 +
>   hw/arm/spitz.c                                |  10 +-
>   hw/arm/versatilepb.c                          |   3 +
>   hw/arm/vexpress.c                             |   3 +
>   hw/arm/xlnx-zcu102.c                          |   4 +
>   hw/arm/z2.c                                   |  12 +-
>   hw/audio/ac97.c                               |   9 +-
>   hw/audio/adlib.c                              |   9 +-
>   hw/audio/cs4231a.c                            |   8 +-
>   hw/audio/es1370.c                             |   8 +-
>   hw/audio/gus.c                                |   6 +-
>   hw/audio/hda-codec.c                          |  37 +-
>   hw/audio/intel-hda.c                          |  25 +-
>   hw/audio/intel-hda.h                          |   2 +-
>   hw/audio/lm4549.c                             |   7 +-
>   hw/audio/lm4549.h                             |   3 +-
>   hw/audio/meson.build                          |   1 -
>   hw/audio/pcspk.c                              |  15 +-
>   hw/audio/pl041.c                              |   2 +-
>   hw/audio/sb16.c                               |   9 +-
>   hw/audio/soundhw.c                            | 177 ------
>   hw/audio/wm8750.c                             |   5 +-
>   hw/core/machine.c                             |  23 +
>   hw/display/xlnx_dp.c                          |  12 +-
>   hw/input/tsc210x.c                            |  79 ++-
>   hw/ppc/prep.c                                 |   4 +
>   hw/usb/dev-audio.c                            |   5 +-
>   include/hw/audio/soundhw.h                    |  15 -
>   include/hw/boards.h                           |   1 +
>   qemu-options.hx                               |  37 --
>   .../codeconverter/test_regexps.py             |   1 -
>   softmmu/qdev-monitor.c                        |   2 -
>   softmmu/vl.c                                  |  10 -
>   tests/qtest/ac97-test.c                       |   3 +-
>   tests/qtest/es1370-test.c                     |   3 +-
>   tests/qtest/fuzz/generic_fuzz_configs.h       |   6 +-
>   tests/qtest/intel-hda-test.c                  |  15 +-
>   ui/vnc.c                                      |  15 +-
>   61 files changed, 329 insertions(+), 1140 deletions(-)
>   delete mode 100644 audio/audio_legacy.c
>   delete mode 100644 hw/audio/soundhw.c
>   delete mode 100644 include/hw/audio/soundhw.h

Thanks for the tidy-up! I'm not too familiar with the audio code, however one thing I 
noticed is that in patch 11 you are using qdev_prop_set_string() to set the audiodev 
for the machines.

For CharDevs there already exists a qdev_prop_set_chr() function which is used to 
assign the chardev backend to the device, so I'm wondering if it makes sense to add a 
similar qdev_prop_set_audiodev() function in the same way? Then if the method of 
referencing the audiodev from the device ever changes from being a string containing 
the name, it won't require updating all of the callers.

Finally a quick glance at the tsc210x and lm4549 devices indicates that they are 
using global device _init() functions which shouldn't really be used in modern 
implementations. If you are interested in QOMify-ing these devices as part of this 
work, then I can certainly help provide some pointers for getting started.


ATB,

Mark.