linux-kernel - Re: [PATCH] ALSA: hda: cs35l56: Perform firmware download in the background

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Date: Thu, 02 May 2024 12:25:51 +0200
From: Takashi Iwai <tiwai@...e.de>
To: Simon Trimmer <simont@...nsource.cirrus.com>
Cc: 'Richard Fitzgerald'
	<rf@...nsource.cirrus.com>,
	<tiwai@...e.com>,
	<linux-sound@...r.kernel.org>,
	<alsa-devel@...a-project.org>,
	<linux-kernel@...r.kernel.org>,
	<patches@...nsource.cirrus.com>
Subject: Re: [PATCH] ALSA: hda: cs35l56: Perform firmware download in the background

On Thu, 02 May 2024 12:17:48 +0200,
Simon Trimmer wrote:
> 
> > -----Original Message-----
> > From: Takashi Iwai <tiwai@...e.de>
> > Sent: Thursday, May 2, 2024 10:53 AM
> > To: Richard Fitzgerald <rf@...nsource.cirrus.com>
> > Cc: Simon Trimmer <simont@...nsource.cirrus.com>; tiwai@...e.com; linux-
> > sound@...r.kernel.org; alsa-devel@...a-project.org; linux-
> > kernel@...r.kernel.org; patches@...nsource.cirrus.com
> > Subject: Re: [PATCH] ALSA: hda: cs35l56: Perform firmware download in the
> > background
> > 
> > On Thu, 02 May 2024 11:21:36 +0200,
> > Richard Fitzgerald wrote:
> > >
> > > On 02/05/2024 08:34, Takashi Iwai wrote:
> > > > On Wed, 01 May 2024 13:17:55 +0200,
> > > > Simon Trimmer wrote:
> > > >> @@ -964,6 +1011,14 @@ int cs35l56_hda_common_probe(struct
> > cs35l56_hda *cs35l56, int hid, int id)
> > > >>   	mutex_init(&cs35l56->base.irq_lock);
> > > >>   	dev_set_drvdata(cs35l56->base.dev, cs35l56);
> > > >>   +	cs35l56->dsp_wq =
> > > >> create_singlethread_workqueue("cs35l56-dsp");
> > > >> +	if (!cs35l56->dsp_wq) {
> > > >> +		ret = -ENOMEM;
> > > >> +		goto err;
> > > >> +	}
> > > >
> > > > Do we really need a dedicated workqueue?  In most usages, simple
> > > > schedule_work*() works fine and is recommended.
> > > >
> > >
> > > On a slow I2C bus with 4 amps this work could take over 2 seconds.
> > > That seems too long to be blocking a global system queue. We use a
> > > dedicated queue in the ASoC driver.
> > >
> > > Also if we queue work on an ordered (single-threaded) system queue the
> > > firmware won't be downloaded to multiple amps in parallel, so we don't
> > > get the best use of the available bus bandwidth.
> > 
> > OK, that sounds like a sensible argument.
> > 
> > But the patch has no call of a queue destructor.  Won't it leak
> > resources?
> 
> Oops that's a good spot - I missed that and will send a v2

If you submit a newer version, it'd be appreciated to explain about
the workqueue usage in the patch description, too.


thanks,

Takashi