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

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Date:   Thu, 24 Jan 2019 17:04:37 +0100
From:   Takashi Iwai <tiwai@...e.de>
To:     "Sameer Pujar" <spujar@...dia.com>
Cc:     <abhijeet.kumar@...el.com>, <perex@...ex.cz>,
        <alsa-devel@...a-project.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ALSA: hda: runtime PM is always active

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@...dia.com>
> Reviewed-by: Ravindra Lokhande <rlokhande@...dia.com>
> Reviewed-by: Mohan Kumar D <mkumard@...dia.com>

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.)


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
> 
>