linux-kernel - Re: [RFC]PM_QOS api update to use handles 5/5 (pcm updates)

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Date:	Mon, 30 Nov 2009 10:06:31 +0100
From:	Takashi Iwai <tiwai@...e.de>
To:	640E9920 <640e9920@...il.com>
Cc:	linux-pm@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	perex@...ex.cz
Subject: Re: [RFC]PM_QOS api update to use handles 5/5 (pcm updates)

At Sun, 29 Nov 2009 17:10:46 -0800,
640E9920 wrote:
> 
> diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
> index ab73edf..e52eeec 100644
> --- a/sound/core/pcm_native.c
> +++ b/sound/core/pcm_native.c
> @@ -447,11 +447,12 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
>  	snd_pcm_timer_resolution_change(substream);
>  	runtime->status->state = SNDRV_PCM_STATE_SETUP;
>  
> -	pm_qos_remove_requirement(PM_QOS_CPU_DMA_LATENCY,
> -				substream->latency_id);
> +	if (substream->latency_pm_qos_req)
> +		pm_qos_remove_request(substream->latency_pm_qos_req);
> +

Since pm_qos_add_request() below isn't called always,
substream->latency_pm_qos_req needs the NULL re-initialization after
removal, I guess.  The PCM hw_params and hw_free callbacks can be
called multiple times, and invalid pointers may be passed.

>  	if ((usecs = period_to_usecs(runtime)) >= 0)
> -		pm_qos_add_requirement(PM_QOS_CPU_DMA_LATENCY,
> -					substream->latency_id, usecs);
> +		substream->latency_pm_qos_req = pm_qos_add_request(
> +					PM_QOS_CPU_DMA_LATENCY, usecs);
>  	return 0;
>   _error:
>  	/* hardware might be unuseable from this time,
> @@ -506,8 +507,7 @@ static int snd_pcm_hw_free(struct snd_pcm_substream *substream)
>  	if (substream->ops->hw_free)
>  		result = substream->ops->hw_free(substream);
>  	runtime->status->state = SNDRV_PCM_STATE_OPEN;
> -	pm_qos_remove_requirement(PM_QOS_CPU_DMA_LATENCY,
> -		substream->latency_id);
> +	pm_qos_remove_request(substream->latency_pm_qos_req);
>  	return result;

Ditto.


thanks,

Takashi
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