linux-kernel - Re: [alsa-devel] [PATCH 15/27] ALSA: hda - Use timecounter

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Date:   Fri, 15 Dec 2017 18:10:09 +0100
From:   Takashi Iwai <tiwai@...e.de>
To:     Richard Cochran <richardcochran@...il.com>
Cc:     Sagar Arun Kamble <sagar.a.kamble@...el.com>,
        linux-kernel@...r.kernel.org, alsa-devel@...a-project.org,
        Vinod Koul <vinod.koul@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [alsa-devel] [PATCH 15/27] ALSA: hda - Use timecounter_initialize interface

On Fri, 15 Dec 2017 17:51:25 +0100,
Richard Cochran wrote:
> 
> On Fri, Dec 15, 2017 at 12:10:47PM +0100, Takashi Iwai wrote:
> 
> > > -	struct cyclecounter *cc = &azx_dev->tc.cc;
> 
> > > -	cc->read = azx_cc_read;
> > > -	cc->mask = CLOCKSOURCE_MASK(32);
> 
> > > -	cc->mult = 125; /* saturation after 195 years */
> > > -	cc->shift = 0;
> 
> I want to get away from this mess of open coded structure
> initialization and use a proper functional interface instead.

I agree that a proper functional interface would be better, too.
But not a form like foo(501, 21, 10, 499, 5678).  
In C syntax, you may more easily pass a wrong value than open codes.

> > >  	nsec = 0; /* audio time is elapsed time since trigger */
> > > -	timecounter_init(tc, nsec);
> > > +	timecounter_initialize(tc,
> > > +			       azx_cc_read,
> > > +			       CLOCKSOURCE_MASK(32),
> > > +			       125, /* saturation after 195 years */
> > > +			       0,
> > > +			       nsec);
> > 
> > Hmm, a function with so many arguments is difficult to remember and is
> > often error-prone.  By this transition, it becomes harder to read
> > through.
> 
> Please suggest a better way.

I have no good idea ATM, sorry.

Or can we provide simpler versions for covering some defaults?  At
least reducing the number of arguments would make things easier.


Takashi