Re: [PATCH] ALSA: hda: runtime PM is always active

[Sameer Pujar]

On 1/25/2019 12:13 AM, Takashi Iwai wrote:
> On Thu, 24 Jan 2019 19:15:12 +0100,
> Sameer Pujar wrote:
> > On 1/24/2019 9:34 PM, Takashi Iwai wrote:
> > > On Thu, 24 Jan 2019 16:57:11 +0100,
> > > Sameer Pujar wrote:
> > > > The runtime PM count is incremented and set to active during hda codec
> > > > device init, but it is decremented and set to suspend during exit only.
> > > > Hence the runtime PM status is always active and hda device cannot be
> > > > put to runtime suspend. Keeping device usage active for entire period,
> > > > though nothing really happening on the device, seems unnecessary.
> > > >
> > > > This patch avoides incrementing runtime PM usage count of the device.
> > > >
> > > > Signed-off-by: Sameer Pujar <spujar@xxxxxxxxxx>
> > > > Reviewed-by: Ravindra Lokhande <rlokhande@xxxxxxxxxx>
> > > > Reviewed-by: Mohan Kumar D <mkumard@xxxxxxxxxx>
> > > This breaks the existing things, I'm afraid.
> > > Did you really test and verify the behavior...?
> > >
> > > The runtime PM refcount is decremented at snd_hda_codec_register(),
> > > and that's the place to let runtime suspend of the codec really
> > > effective.  (It's not about the controller, though.)
> > It worked fine at my end. I could put the device to runtime suspend
> > and resume it back multiple times.
> > Since you are suggesting it could break things, let me rework on the
> > patch and dig up a little more to
> > see if there is better way to fix this.
> Well, I don't see what you want to "fix".  Do you see any bug?
I was expecting the device to be runtime suspended, once probe is 
finished, until I playback something on it.
But it appears that rutntime PM is always active and runtime PM suspend 
callback never happens.
> thanks,
>
> Takashi
>
> > Thanks,
> > Sameer.
> >
> > > thanks,
> > >
> > > Takashi
> > >
> > >
> > > > ---
> > > >    sound/hda/hdac_device.c | 6 ------
> > > >    1 file changed, 6 deletions(-)
> > > >
> > > > diff --git a/sound/hda/hdac_device.c b/sound/hda/hdac_device.c
> > > > index 95b073e..72aa342 100644
> > > > --- a/sound/hda/hdac_device.c
> > > > +++ b/sound/hda/hdac_device.c
> > > > @@ -31,9 +31,6 @@ static void default_release(struct device *dev)
> > > >     *
> > > >     * Returns zero for success or a negative error code.
> > > >     *
> > > > - * This function increments the runtime PM counter and marks it active.
> > > > - * The caller needs to turn it off appropriately later.
> > > > - *
> > > >     * The caller needs to set the device's release op properly by itself.
> > > >     */
> > > >    int snd_hdac_device_init(struct hdac_device *codec, struct hdac_bus *bus,
> > > > @@ -55,8 +52,6 @@ int snd_hdac_device_init(struct hdac_device *codec, struct hdac_bus *bus,
> > > >    	codec->bus = bus;
> > > >    	codec->addr = addr;
> > > >    	codec->type = HDA_DEV_CORE;
> > > > -	pm_runtime_set_active(&codec->dev);
> > > > -	pm_runtime_get_noresume(&codec->dev);
> > > >    	atomic_set(&codec->in_pm, 0);
> > > >      	err = snd_hdac_bus_add_device(bus, codec);
> > > > @@ -123,7 +118,6 @@ EXPORT_SYMBOL_GPL(snd_hdac_device_init);
> > > >     */
> > > >    void snd_hdac_device_exit(struct hdac_device *codec)
> > > >    {
> > > > -	pm_runtime_put_noidle(&codec->dev);
> > > >    	snd_hdac_bus_remove_device(codec->bus, codec);
> > > >    	kfree(codec->vendor_name);
> > > >    	kfree(codec->chip_name);
> > > > --
> > > > 2.7.4