On Mon, 10 Dec 2018 21:52:05 +0100, Pierre-Louis Bossart wrote: > > > On 12/9/18 3:33 AM, Takashi Iwai wrote: > > The current HD-audio code manages the DRM audio power via too complex > > redirections, and this seems even still unbalanced in a corner case as > > Intel DRM CI has been intermittently reporting. This patch is a big > > surgery for addressing the complexity and the possible unbalance. > > > > Basically the patch changes the display PM in the following ways: > > > > - Both HD-audio controller and codec drivers call a single helper, > > snd_hdac_display_power(). (Formerly, the display power control from > > a codec was done indirectly via link_power bus ops.) > > > > - snd_hdac_display_power() receives the codec address index. For > > turning on/off from the controller, pass HDA_CODEC_IDX_CONTROLLER. > > The need for this virtual index==16 isn't fully clear to me, > especially if you use the bitfields instead of reference counts. > > Isn't there a risk of the controller setting the bit16 to zero, but > you still have bit4 on (assuming the idx is 4). If you use this > virtual index, it should override the actual physical bits when > set/cleared. This is the index for a controller, i.e. we'd need bits for the max number of codecs + 1. Actually we do support only up to 8 codecs (HDA_MAX_CODECS), so it should be 8, instead of 16, too. I'll update to be HDA_MAX_CODECS. > Or is this meant to actually implement a preemption mechanism, where > the display power remains on for as long as the controller wishes, > regardless of what the patch_hdmi and hdac_hdmi code requests? Right. That's the mechanism at the initial phase, we need the display power on while probing the codec, i.e. before identifying the codec ID. > Also don't we already have the HDMI codec address already after the > probe, so couldn't we provide the address directly? The resume seemed requiring the controller to take the display power at first, so the same mechanism is used. thanks, Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
