Re: [PATCH v8 2/7] ALSA: Jack: refactoring snd_kctl_jack_new to support embedded kctl

[Takashi Iwai <tiwai@suse.de>]

At Wed, 22 Apr 2015 12:40:43 +0000,
Jie, Yang wrote:
> 
> > -----Original Message-----
> > From: Takashi Iwai [mailto:tiwai@suse.de]
> > Sent: Wednesday, April 22, 2015 7:33 PM
> > To: Jie, Yang
> > Cc: broonie@kernel.org; alsa-devel@alsa-project.org; Girdwood, Liam R;
> > tanu.kaskinen@linux.intel.com
> > Subject: Re: [PATCH v8 2/7] ALSA: Jack: refactoring snd_kctl_jack_new to
> > support embedded kctl
> > 
> > At Wed, 22 Apr 2015 14:03:48 +0800,
> > Jie Yang wrote:
> > >
> > > Move available index get part into snd_kctl_jack_new(), also add kctl
> > > name regenerating func to remove redundant " Jack" which is passed in
> > > wrongly in some cases.
> > 
> > The subject doesn't match with this description well.
>  
> How about changing them as below:
> 
> ALSA: Jack: handle jack embedded kcontrol creating within ctljack
> 
> In ctljack.c, add function get_available_index() to allocate
> index for new kcontrol, and jack_kctl_name_gen() to remove
> redundant " Jack" which is passed in wrongly in some cases.
> 
> > 
> > 
> > > Signed-off-by: Jie Yang <yang.jie@intel.com>
> > > ---
> > >  include/sound/control.h  |  2 +-
> > >  sound/core/ctljack.c     | 39 +++++++++++++++++++++++++++++++++++-
> > ---
> > >  sound/core/jack.c        |  2 +-
> > >  sound/pci/hda/hda_jack.c |  2 +-
> > >  4 files changed, 38 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/include/sound/control.h b/include/sound/control.h index
> > > 75f3054..58751a0 100644
> > > --- a/include/sound/control.h
> > > +++ b/include/sound/control.h
> > > @@ -252,7 +252,7 @@ void snd_ctl_sync_vmaster(struct snd_kcontrol
> > *kctl, bool hook_only);
> > >   * Helper functions for jack-detection controls
> > >   */
> > >  struct snd_kcontrol *
> > > -snd_kctl_jack_new(const char *name, int idx, void *private_data);
> > > +snd_kctl_jack_new(const char *name, struct snd_card *card);
> > >  void snd_kctl_jack_report(struct snd_card *card,
> > >  			  struct snd_kcontrol *kctl, bool status);
> > >
> > > diff --git a/sound/core/ctljack.c b/sound/core/ctljack.c index
> > > e4b38fb..b631996 100644
> > > --- a/sound/core/ctljack.c
> > > +++ b/sound/core/ctljack.c
> > > @@ -31,15 +31,46 @@ static struct snd_kcontrol_new jack_detect_kctl = {
> > >  	.get = jack_detect_kctl_get,
> > >  };
> > >
> > > +static int get_available_index(struct snd_card *card, const char
> > > +*name) {
> > > +	struct snd_ctl_elem_id sid;
> > > +
> > > +	memset(&sid, 0, sizeof(sid));
> > > +
> > > +	sid.index = 0;
> > > +	sid.iface = SNDRV_CTL_ELEM_IFACE_CARD;
> > > +	strlcpy(sid.name, name, sizeof(sid.name));
> > > +
> > > +	while (snd_ctl_find_id(card, &sid))
> > > +		sid.index++;
> > > +
> > > +	return sid.index;
> > > +}
> > > +
> > > +static void jack_kctl_name_gen(char *name, const char *src_name, int
> > > +size) {
> > > +	size_t count = strlen(src_name);
> > > +	bool need_cat = true;
> > > +
> > > +	/* remove redundant " Jack" from src_name */
> > > +	if (count >= 5)
> > > +		need_cat = strncmp(&src_name[count - 5], " Jack", 5) ? true :
> > > +false;
> > > +
> > > +	snprintf(name, size, need_cat ? "%s Jack" : "%s", src_name);
> > > +
> > > +}
> > > +
> > >  struct snd_kcontrol *
> > > -snd_kctl_jack_new(const char *name, int idx, void *private_data)
> > > +snd_kctl_jack_new(const char *name, struct snd_card *card)
> > >  {
> > >  	struct snd_kcontrol *kctl;
> > > -	kctl = snd_ctl_new1(&jack_detect_kctl, private_data);
> > > +
> > > +	kctl = snd_ctl_new1(&jack_detect_kctl, card);
> > 
> > Why changing the private data?  Did it really work...?
>  
> After this refactoring series, only jack.c:snd_jack_kctl_new() will call this
> snd_kctl_jack_new() with struct snd_card * passed in, so I changed it
> here, to make it easier for reading.
> 
> Here struct snd_card * will be cast to void * in snd_ctl_new1().
> 
> Actually, I can keep it as before, then struct snd_card * will be cast to
> void * in snd_kctl_jack_new().
> 
> Seems no big difference with these two method? If you like, I can change
> It back.

You break the bisectionability in your series.

Try to build and test at *each* commit whether it works as expected.
Since snd_kctl_jack_new() is still called from hda_jack.c at this
commit, it'll certainly crash when the jack is actually handled.
Or, maybe it's even before that -- it may result in double jacks.

Especially test with several kconfigs to build (with and without
CONFIG_SND_HDA_INPUT_JACK and CONFIG_SND_JACK), and test with the
actual HD-audio driver.

Keeping things working isn't an easy task, but it's often worthwhile.
Once when you have done, you have idea how to manage a patch series.


Takashi