[alsa-devel] [PATCH 1/5] ASoC: wm8731: rework power management
nicolas.ferre at atmel.com
Thu Jun 30 17:04:02 CEST 2011
Le 30/06/2011 15:57, Nicolas Ferre :
> Le 29/06/2011 19:11, Mark Brown :
>> On Wed, Jun 29, 2011 at 08:00:15PM +0200, Nicolas Ferre wrote:
>> Don't mix multiple changes into a single patch! There's no perceptible
>> code overlap between these so I don't understand why you've merged them,
>> it just makes review harder and the changelog less descriptive.
>>> - preserve crystal oscillator across suspend/resume sequence:
>>> enabled by default, it should be kept enabled on resume.
>> This isn't what your code does...
>>> snd_soc_write(codec, WM8731_ACTIVE, 0x0);
>>> - snd_soc_write(codec, WM8731_PWR, 0xffff);
>>> + /* standby: keep crystal oscillator enabled */
>>> + snd_soc_write(codec, WM8731_PWR, 0x00df);
>> This doesn't keep the crystal oscillator enabled, this forces it on in
>> suspend (and without looking at the datasheet it also changes way more
>> than the one register bit I'd expect to be changed). If the system
>> isn't using the oscillator then that's not good.
>> I'd expect to see a change to using snd_soc_update_bits() based on your
>> description, or more likely something more involved.
> First of all, I experienced issues while not having OSC enabled during suspend/resume cycle. Am I right supposing that, if using oscillator to clock the codec, I have to keep it running during a suspend/resume cycle?
> Is something like this sounds like an acceptable option or we need something more sophisticated?
> @@ -481,7 +481,10 @@ static int wm8731_set_bias_level(struct snd_soc_codec *codec,
> case SND_SOC_BIAS_OFF:
> snd_soc_write(codec, WM8731_ACTIVE, 0x0);
> - snd_soc_write(codec, WM8731_PWR, 0xffff);
> + reg = 0xdf;
> + if (wm8731->sysclk_type == WM8731_SYSCLK_XTAL)
Actually it is: if... != WM8731_SYSCLK_XTAL
> + reg |= 1 << 0x5;
> + snd_soc_update_bits(codec, WM8731_PWR, 0x00ff, reg);
And maybe here a simple snd_soc_write() is sufficient...
> And, yes, there is only 8 bits dedicated to power down control in this register.
> Best regards,
More information about the Alsa-devel