[alsa-devel] [PATCH 00/12] ASoC: intel: add device_link to HDMI audio

[Takashi Iwai]

On Thu, 11 Apr 2019 14:24:13 +0200,
Yang, Libin wrote:
> 
> Hi Takashi,
> 
> >-----Original Message-----
> >From: Takashi Iwai [mailto:tiwai at suse.de]
> >Sent: Thursday, April 11, 2019 6:10 PM
> >To: Yang, Libin <libin.yang at intel.com>
> >Cc: alsa-devel at alsa-project.org; broonie at kernel.org; pierre-
> >louis.bossart at linux.intel.com
> >Subject: Re: [PATCH 00/12] ASoC: intel: add device_link to HDMI audio
> >
> >On Thu, 11 Apr 2019 11:34:47 +0200,
> >libin.yang at intel.com wrote:
> >>
> >> From: Libin Yang <libin.yang at intel.com>
> >>
> >> This patchset add the device_link between the machine devices of intel
> >> boards and HDMI audio codec. This can make sure that display audio
> >> power domain is always turned on before operating on the HDMI audio
> >> codecs.
> >>
> >> patch 2 adds the helper functions in a new created header file.
> >> However skl_hda_dsp_generic doesn't use these helper functions because
> >> skl_hda_dsp_generic is a special driver, the add link and delete link
> >> operations are in different source code files.
> >> If it includes the header file, there is compiling warning.
> >
> >Now I took a look at the core implementation, and wonder whether we may
> >drop the device_link_del() call if we create the link with
> >DL_FLAG_AUTOREMOVE_CONSUMER?  If that works, you don't have to track
> >the link pointer, so it can be dropped as well; i.e. the only addition would be
> >just the extra call of device_link_add() for each machine driver.
> 
> In the machine drivers, each dai_link will call device_link_add(). So I use
> the link pointer to check whether it is already created or not to avoid
> creating the link several times. Like the below code:
> +       if (!(*link))
> +               *link = device_link_add(consumer, supplier, DL_FLAG_RPM_ACTIVE);

Yes, that's fine.  What I meant is the rest part, device_link_del()
call and keeping the link pointer.  Both look superfluous once when
you create a device link with DL_FLAG_AUTOREMOVE_CONSUMER flag, then
the device link will be automatically cleaned up at the device
removal.


thanks,

Takashi