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    ALSA: hda - remove unnecessary msleep on power state transitions · dd2b4a7a
    Zhang, Rui 提交于
    This will save ~15ms boot time.
    
    The first 10ms sleep was introduced in commit d2595d86 for (buggy)
    Cxt codecs, so better to limit the sleep to the problem hardware.
    
    For the second 10ms sleep, the HDA spec says:
    
    Power State[1:0]:
    00: Node Power state (D0) is fully on.
    01: Node Power state (D1) allows for (does not require) the lowest possible power consuming state from which it
    can return to the "fully on" state (D0) within 10 ms, excepting analog pass through circuits (e.g., CD analog
    playback) which must remain fully on.
    10: Node Power state (D2) allows for (does not require) the lowest possible power consuming state from which it
    can return to the "fully on" state (D0) within 10 ms. For modems, this is the "wake on ring" power state.
    11: Node Power state (D3) allows for (does not require) lowest possible power consuming state under software
    control. Note that any low power state set by software must retain sufficient operational capability to properly
    respond to subsequent software Power State command.
    
    So 10ms is actually the max wait time. It should be safe to
    remove/reduce it and rely on the loop of 1ms-sleeps.
    
    CC: Marc Boucher <marc@linuxant.com>
    CC: Arjan van de Ven <arjan@linux.intel.com>
    Signed-off-by: NZhang Rui <rui.zhang@intel.com>
    Signed-off-by: NWu Fengguang <fengguang.wu@intel.com>
    Signed-off-by: NTakashi Iwai <tiwai@suse.de>
    dd2b4a7a
hda_codec.c 120.6 KB