[alsa-devel] [PATCH v2] ALSA: x86: Select CONFIG_HDMI_LPE_AUDIO as default

Ian W MORRISON ianwmorrison at gmail.com
Tue Mar 21 16:09:52 CET 2017 

On 21 March 2017 at 16:27, Takashi Iwai <tiwai at suse.de> wrote:

> On Mon, 20 Mar 2017 23:02:25 +0100,
> Ian W MORRISON wrote:
> >
> > On 21 March 2017 at 04:57, Takashi Iwai <tiwai at suse.de> wrote:
> >
> > > On Mon, 20 Mar 2017 16:12:01 +0100,
> > > Ian W MORRISON wrote:
> > > >
> > > > On 20 March 2017 at 21:04, Takashi Iwai <tiwai at suse.de> wrote:
> > > >
> > > > > On Mon, 20 Mar 2017 10:41:07 +0100,
> > > > > Ian W MORRISON wrote:
> > > > > >
> > > > > > On 20 March 2017 at 19:41, Takashi Iwai <tiwai at suse.de> wrote:
> > > > > >
> > > > > > > On Mon, 20 Mar 2017 09:17:30 +0100,
> > > > > > > Ian W MORRISON wrote:
> > > > > > > >
> > > > > > > > Oops ... forgot to copy alsa-devel and Pierre-Louis.
> > > > > > > >
> > > > > > > > On 20 March 2017 at 18:59, Takashi Iwai <tiwai at suse.de>
> wrote:
> > > > > > > >
> > > > > > > > > On Mon, 20 Mar 2017 08:42:32 +0100,
> > > > > > > > > Ian W MORRISON wrote:
> > > > > > > > > >
> > > > > > > > > > The upstream kernel builds for distributions such as
> Ubuntu
> > > > > which now
> > > > > > > > > > includes binary packages for v4.11 mainline kernel
> release
> > > > > > > candidates are
> > > > > > > > > > promoted as a way of testing upstream kernels to to
> confirm
> > > that
> > > > > > > upstream
> > > > > > > > > > has fixed a specific issue (see https://wiki.ubuntu.com/
> > > > > > > > > > Kernel/MainlineBuilds).
> > > > > > > > > >
> > > > > > > > > > Unfortunately the long awaited patch for providing HDMI
> audio
> > > > > > > support for
> > > > > > > > > > Bay Trail and Cherry Trail devices does not include this
> > > support
> > > > > > > through
> > > > > > > > > a
> > > > > > > > > > module built by default.
> > > > > > > > > >
> > > > > > > > > > Through including by default of the two associated CONFIG
> > > > > settings
> > > > > > > > > (SND_X86
> > > > > > > > > > and HDMI_LPE_AUDIO), upstream kernel builds would
> > > automatically
> > > > > > > provide
> > > > > > > > > the
> > > > > > > > > > much desired HDMI audio support by default.
> > > > > > > > > >
> > > > > > > > > > This patch uses a Kconfig 'default' statement to include
> the
> > > > > driver
> > > > > > > as
> > > > > > > > > > default.
> > > > > > > > > >
> > > > > > > > > > Changes in version 2: CONFIG_SND_X86 now a bool and
> changed
> > > > > default
> > > > > > > m to
> > > > > > > > > > default y
> > > > > > > > > >
> > > > > > > > > > Signed-off-by: Ian W Morrison <linuxium at linuxium.com.au>
> > > > > > > > > > ---
> > > > > > > > > >  sound/x86/Kconfig | 4 +++-
> > > > > > > > > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > > > > > > > >
> > > > > > > > > > diff --git a/sound/x86/Kconfig b/sound/x86/Kconfig
> > > > > > > > > > index 84c8f8fc..cac2270 100644
> > > > > > > > > > --- a/sound/x86/Kconfig
> > > > > > > > > > +++ b/sound/x86/Kconfig
> > > > > > > > > > @@ -1,6 +1,7 @@
> > > > > > > > > >  menuconfig SND_X86
> > > > > > > > > > -       tristate "X86 sound devices"
> > > > > > > > > > +       bool "X86 sound devices"
> > > > > > > > > >         depends on X86
> > > > > > > > > > +       default y
> > > > > > > > >
> > > > > > > > > This one is OK, but ...
> > > > > > > > >
> > > > > > > > > >         ---help---
> > > > > > > > > >           X86 sound devices that don't fall under SoC or
> PCI
> > > > > > > categories
> > > > > > > > > >
> > > > > > > > > > @@ -9,6 +10,7 @@ if SND_X86
> > > > > > > > > >  config HDMI_LPE_AUDIO
> > > > > > > > > >         tristate "HDMI audio without HDaudio on Intel
> Atom
> > > > > platforms"
> > > > > > > > > >         depends on DRM_I915
> > > > > > > > > > +       default y
> > > > > > > > >
> > > > > > > > > ... this is wrong.  Each driver config itself should be
> left
> > > > > > > > > unspecified.
> > > > > > > > >
> > > > > > > > > It's distributor's job to choose the right config here.
> > > > > > > > >
> > > > > > > > > Actually this goes back to one of my earlier points: A
> > > distributor
> > > > > > > doesn't
> > > > > > > > have to set 'HDMI' as HDMI audio is automatically provided.
> > > > > > >
> > > > > > > Provided by who...?
> > > > > > >
> > > > > >
> > > > > >
> > > > > > I suppose it is provided as a result of the architecture one
> runs the
> > > > > > primary Makefile on. With 'uname -m' returning 'x86_64' running
> 'make
> > > > > > defconfig' results in 'CONFIG_HDMI=y' being set so
> > > > > 'drivers/video/Makefile'
> > > > > > automatically makes 'drivers/video/hdmi.c' and as
> > > > > > 'arch/x86/configs/x86_64_defconfig' includes 'CONFIG_DRM=y' and
> > > > > > 'CONFIG_DRM_I915=y' and 'drivers/gpu/drm/i915/Makefile' makes
> > > > > > 'intel_audio.c'.
> > > > >
> > > > > The defconfig stuff supports only the limited device sets that are
> > > > > supposed to be very common.  Is HDMI_LPE_AUDIO classified really as
> > > > > such a thing?  I don't know...
> > > > >
> > > > >
> > > > In this instance I'd suggest that HDMI_LPE_AUDIO is common as
> without it
> > > > you do not get HDMI audio on all x86_64 devices. However see my
> comment
> > > > below.
> > > >
> > > >
> > > > >
> > > > > > > > This is just an
> > > > > > > > extension because by setting 'HDMI_LPE_AUDIO' the missing
> audio
> > > > > support
> > > > > > > for
> > > > > > > > BYT and CHT SoCs is then provided. Therefore, in this albeit
> > > unusual
> > > > > > > > instance, I reason is it appropriate to set HDMI_LPE_AUDIO so
> > > that
> > > > > audio
> > > > > > > is
> > > > > > > > automatically provided regardless of distribution. If a
> > > distributor
> > > > > > > didn't
> > > > > > > > want to allow audio for BYT and CHT SoC based devices running
> > > their
> > > > > > > distro
> > > > > > > > then they could always remove it from their distro specific
> > > config.
> > > > > > >
> > > > > > > It's a wrong approach.  What we're discussing about is just a
> > > > > > > configuration for a new individual driver, and the same rule
> > > should be
> > > > > > > applied to it like others.
> > > > > > >
> > > > > > > Check other drivers.  See whether default=y (or =m) is set to
> > > > > > > CONFIG_E1000E, as a random example.  With your argument, it
> > > should  be
> > > > > > > set to y or m as default, since the Ethernet functionality is
> > > already
> > > > > > > provided by the network core.
> > > > > > >
> > > > > > > In general, we don't set the default values to the driver
> configs
> > > > > > > unless there is a VERY specific reason to do so.
> > > > > > >
> > > > > > >
> > > > > > I'm trying to get HDMI audio by default for BYT & CHT SoC but
> > > currently
> > > > > > this requires 'CONFIG_HDMI_LPE_AUDIO' set with a value of 'm'. I
> > > don't
> > > > > want
> > > > > > to argue a 'special case' or promote a 'wrong approach' but just
> get
> > > HDMI
> > > > > > audio working so is there another way to achieve this?
> > > > >
> > > > > What's wrong with manually setting CONFIG_HDMI_LPE_AUDIO=m or =y?
> > > > > IOW, do all features on your CHT/BYT machines work without
> adjusting
> > > > > manually after defconfig?  If you have to do it in anyway, what
> makes
> > > > > it special for HDMI_LPD_AUDIO?
> > > > >
> > > > >
> > > > I've just tested various scenarios using a variety of devices with
> > > > v4.11-rc3. Having CONFIG_HDMI_LPE_AUDIO set by default is sufficient
> to
> > > get
> > > > audio on BYT/CHT devices over HDMI.
> > > >
> > > > For example installing Ubuntu 16.04.2 on a BYT/CHT device, then
> upgrading
> > > > the kernel to v4.11-rc3 using the deb-binary from
> > > http://kernel.ubuntu.com/~
> > > > kernel-ppa/mainline/v4.11-rc3/ (an example of a current distro which
> is
> > > > compiling without setting CONFIG_HDMI_LPE_AUDIO) and there is no
> audio
> > > over
> > > > HDMI. Alternatively downloading v4.11-rc3 source, making defconfig,
> > > > manually setting CONFIG_HDMI_LPE_AUDIO, compiling and installing the
> > > > kernel on the BYT/CHT device will give you audio over HDMI.
> > > >
> > > > If the BYT/CHT device has other sound cards (e.g accessed via a
> headphone
> > > > jack) then audio without setting CONFIG_HDMI_LPE_AUDIO may be
> possible
> > > > depending on the codec used and whether it is provided by default in
> the
> > > > kernel. So for example a Tronsmart Ara (CHT) device has audio over
> > > > headphones using the pre-compiled deb-binary above but no audio over
> > > HDMI.
> > > > Whereas with a (1st gen) Intel Compute Stick (BYT) device no audio is
> > > > possible using the pre-compiled deb-binary as the device only has an
> HDMI
> > > > port. To get sound you must therefore currently use a self-compiled
> > > kernel
> > > > with CONFIG_HDMI_LPE_AUDIO set.
> > > >
> > > > Whilst Canonical may set CONFIG_HDMI_LPE_AUDIO to provide audio on
> > > BYT/CHT
> > > > devices by when is unknown and there is no guarantee they actually
> will.
> > > >
> > > > This will be similar for all other distros with the worst case
> scenario
> > > > that no distributor adds CONFIG_HDMI_LPE_AUDIO to their configs
> resulting
> > > > in (arguably) little point including HDMI LPE audio support in the
> > > kernel.
> > > >
> > > > I've laboured the point about 'BYT/CHT devices audio over HDMI' but
> to
> > > > answer your question completely there are other BYT/CHT devices
> > > (typically
> > > > tablets) that need a whole other bunch of patches to fix this and
> that.
> > > > They may need specialist kernel configs with specific settings but
> that
> > > is
> > > > a separate issue to the basic functional need of having audio over
> HDMI.
> > > >
> > > > Does the above explanation justify my current approach or is there an
> > > > alternative that can be considered?
> > >
> > > Sorry, no, you've explained how much you love the HDMI audio, but it
> > > doesn't answer my question clearly.
> > >
> >
> > Whatever love there was is diminishing rapidly!
> >
> > Let me set the context: the range of BYT/CHT devices sold as HDMI sticks
> or
> > HDMI boxes which are designed to connect to an HDMI output device (TV or
> > monitor) and typically have Windows installed as the OS and are used
> > primarily as media PCs, HTPCs or as 'mini' PCs. They become essentially
> > useless for their designated purpose when installed with a mainstream
> Linux
> > based OS such as Ubuntu at the moment because there is no audio over
> HDMI.
>
> Simply because there was no upstream driver.  What does it have to do
> with the default configuration issue we're arguing...?
>
> > > My question is simple: are *all* features the upstream kernel supports
> > > for your device now (e.g. input, network or whatever) enabled by the
> > > pure arch/x86/configs/x86_64_defconfig *without* manually setting the
> > > configs to y or m?  I bet you likely have to set some configs there
> > > manually to m or y.
> > >
> > >
> > No. CONFIG_HDMI_LPE_AUDIO is the only config that needs to be manually
> set
> > to get *all* features from the upstream kernel.
>
> On some of your devices, maybe.  But don't you have a machine with a
> touchscreen or a WiFi / BT?  How does it work without setting the
> config?
>
> > > Then, if the manual selection for such missing configs is acceptable,
> > > what makes the HDMI audio so special and it must be set to y/m as
> > > default, while other devices aren't set like that...?  That's the
> > > question.
> > >
> > >
> > >
> > The requested patch sets CONFIG_HDMI_LPE_AUDIO so mainstream Linux distro
> > kernels would automatically provide the new kernel feature of HDMI LPE
> > audio support.
>
> The feature *is* provided.  The rest you're requesting is something
> different, merely a configuration, and this is exactly what distro
> needs to take care, not the upstream kernel tree.  We don't set it to
> y/m as default unless very specific reason is present.  This argument
> was stated by Linus in the past a few times, too.
>
> So, if you really want to make the default config y/m, please state
> the very reason why this *must* be enabled as default for *all* x86-64
> machines, not only CHT/BYT devices.
>
>
Earlier Update: Further analysis of Canonical's v4.11-rcN build
compared with other
available distro builds of v4.11-rcN leads me to conclude that given
CONFIG_HDMI_LPE_AUDIO is not set by default then Canonical's config is at
fault. Consequently I have raised a bug report
(https://bugs.launchpad.net/ubuntu/+bug/1674523) in order to
(hopefully)
address the issue. I will additionally submit a further patch that
(arguably) improves the current Kconfig file for the CONFIG_HDMI_LPE_AUDIO
setting by creating a specific menu for the CONFIG_HDMI_LPE_AUDIO setting,
adding additional narrative to further explain the function of the
CONFIG_HDMI_LPE_AUDIO setting and removing the subsequently unnecessary
CONFIG_SND_X86 setting. As a result, this patch ([PATCH v2] ALSA: x86:
Select CONFIG_HDMI_LPE_AUDIO as default) is withdrawn.

Final Update: The Canonical bug report
(https://bugs.launchpad.net/ubuntu/+bug/1674523) has been closed as
the maintainer has stated a new v4.11 config will be created once the
v4.11 kernel is included in unstable. ETA two weeks. The additional
patch was submitted, discussed and withdrawn.



>
> Takashi
>

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