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From: Peter Ujfalusi <peter.ujfalusi@nokia.com>
To: alsa-devel@alsa-project.org
Cc: ext Mark Brown <broonie@opensource.wolfsonmicro.com>,
	"lrg@slimlogic.co.uk" <lrg@slimlogic.co.uk>
Subject: Re: [PATCH 1/2] ASoC: tlv320dac33: Revisit the FIFO Mode1 handling
Date: Wed, 28 Jul 2010 08:08:31 +0300	[thread overview]
Message-ID: <201007280808.54390.peter.ujfalusi@nokia.com> (raw)
In-Reply-To: <20100727163243.GA18884@opensource.wolfsonmicro.com>

On Tuesday 27 July 2010 19:32:44 ext Mark Brown wrote:
> I did notice that the default changes from 20ms:
> > -#define LATENCY_TIME_MS		20
> > 
> > +	if (!dac33->mode1_i2c_latency)
> > +		dac33->mode1_i2c_latency = 10000; /* 10ms */
> 
> to 10ms with the new code but that shouldn't be a problem.

Correct.
The LATENCY_TIME_MS was used for two things:
 alarm threshold = LATENCY_TIME_MS / 2
 nSample lower limit = LATENCY_TIME_MS

The new default (10ms) comes from the old alarm threshold time.

There is no real need to limit the nSample for higher value, it is safe to use 
the same time constraint for alarm threshold and nSample lower limit.
The important thing is actually the alarm threshold value here: we need to have 
enough time to handle the interrupt, schedule the work, and write to nSample 
registers (via i2c) within certain amount of time.
Probably naming the mode1_i2c_latency differently, like mode1_latency would be 
better.

Probably it would be better if I resend the series with this change?

Thanks,
Péter

  reply	other threads:[~2010-07-28  5:09 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-07-27  6:46 [PATCH 0/2] ASoC: tlv320dac33: FIFO mode updates Peter Ujfalusi
2010-07-27  6:46 ` [PATCH 1/2] ASoC: tlv320dac33: Revisit the FIFO Mode1 handling Peter Ujfalusi
2010-07-27 16:32   ` Mark Brown
2010-07-28  5:08     ` Peter Ujfalusi [this message]
2010-07-27  6:46 ` [PATCH 2/2] ASoC: tlv320dac33: Add support for automatic FIFO configuration Peter Ujfalusi
2010-07-27 16:33   ` Mark Brown

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