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

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Date: Thu, 2 May 2024 11:17:48 +0100
From: Simon Trimmer <simont@...nsource.cirrus.com>
To: 'Takashi Iwai' <tiwai@...e.de>,
        'Richard Fitzgerald'
	<rf@...nsource.cirrus.com>
CC: <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

> -----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

Cheers,
-Simon