Re: [RFC PATCH 4/4] ALSA - hda: add DP MST support

[Takashi Iwai <tiwai@suse.de>]

On Mon, 07 Mar 2016 15:57:46 +0100,
libin.yang@linux.intel.com wrote:
> 
> From: Libin Yang <libin.yang@linux.intel.com>
> 
> This patch adds the DP MST support in hdmi audio driver.
> ---
>  sound/pci/hda/hda_codec.c  |   3 +
>  sound/pci/hda/patch_hdmi.c | 167 +++++++++++++++++++++++++++++++--------------
>  2 files changed, 120 insertions(+), 50 deletions(-)
> 
> diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
> index 1a42c51..7244f87 100644
> --- a/sound/pci/hda/hda_codec.c
> +++ b/sound/pci/hda/hda_codec.c
> @@ -589,6 +589,9 @@ static int read_pin_defaults(struct hda_codec *codec)
>  		pin->nid = nid;
>  		pin->cfg = snd_hda_codec_read(codec, nid, 0,
>  					      AC_VERB_GET_CONFIG_DEFAULT, 0);
> +		/* all device entries are the same widget control so far
> +		 * fixme: if any codec is different, need fix here
> +		 */
>  		pin->ctrl = snd_hda_codec_read(codec, nid, 0,
>  					       AC_VERB_GET_PIN_WIDGET_CONTROL,
>  					       0);
> diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c
> index 11be04a..26f5efd 100644
> --- a/sound/pci/hda/patch_hdmi.c
> +++ b/sound/pci/hda/patch_hdmi.c
> @@ -144,7 +144,9 @@ struct hdmi_spec {
>  	struct snd_array cvts; /* struct hdmi_spec_per_cvt */
>  	hda_nid_t cvt_nids[4]; /* only for haswell fix */
>  
> -	int num_pins;
> +	int num_pins; /* number of pins (including device entries) */
> +	int num_nids; /* number of pin nids*/
> +	int dev_num;

These new definitions are unclear to me.  Please give a bit more
detailed comments there.  e.g. what actually means "including device
entries"?  You can give some example there.  I suppose num_nids is the
actual number of pins, right?  Also what is dev_num?  It's not an
index, right? 


thanks,

Takashi