At Fri, 29 Nov 2013 02:41:26 +0000, Lin, Mengdong wrote:
-----Original Message----- From: Takashi Iwai [mailto:tiwai@suse.de] Sent: Thursday, November 28, 2013 11:20 PM To: Lin, Mengdong Cc: alsa-devel@alsa-project.org Subject: Re: HD-Audio: can msleep in hda_set_power_state() to D3 be optional?
At Thu, 28 Nov 2013 15:07:48 +0000, Lin, Mengdong wrote:
Hi Takashi,
In hda_set_power_state(), there is a mandatory sleep up to 100ms
before setting state to D3.
/* this delay seems necessary to avoid click noise at power-down */ if (power_state == AC_PWRST_D3) { msleep(codec->epss ? 10 : 100); ... Could this
be optional for specific codecs?
flags = HDA_RW_NO_RESPONSE_FALLBACK; }Some codecs implement their own sleep in patch_ops.suspend() to
avoid the noise.
So is it okay to add a codec flag to decide whether the sleep is necessary
here?
Rather add an integer value to indicate the codec delay, e.g. codec->d3_delay. If it's zero, we can take the default delay (10 or 100) as of now.
How to set the integer value if a codec doesn't need sleep here? To set a very small value or "-1"?
Or make default -1, and >= 0 for explicit delay set by a codec driver. It doesn't matter which way. My point is that it's better to be a value than a boolean flag.
Takashi