[alsa-devel] [PATCH v3 1/1] ALSA: hda - bug fix for invalid connection list of Haswell HDMI codec pins

[David Henningsson]

On 12/18/2012 10:59 PM, mengdong.lin at intel.com wrote:
> From: Mengdong Lin <mengdong.lin at intel.com>
>
> Haswell HDMI codec pins may report invalid connection list entries, which
> will cause failure to play audio via HDMI or Display Port.
>
> So this patch adds fixup for Haswell to workaround this hardware issue:
> enable DP1.2 mode and override the pins' connection list entries with proper
> value.
>
> Signed-off-by: Mengdong Lin <mengdong.lin at intel.com>
> Signed-off-by: Xingchao Wang <xingchao.wang at intel.com>
>
> diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c
> index 71555cc..59abe73 100644
> --- a/sound/pci/hda/patch_hdmi.c
> +++ b/sound/pci/hda/patch_hdmi.c
> @@ -1687,6 +1687,30 @@ static const struct hda_codec_ops generic_hdmi_patch_ops = {
>   	.unsol_event		= hdmi_unsol_event,
>   };
>
> +static void intel_haswell_fixup_connect_list(struct hda_codec *codec)
> +{
> +	unsigned int vendor_param;
> +	hda_nid_t list[3] = {0x2, 0x3, 0x4};
> +
> +	vendor_param = snd_hda_codec_read(codec, 0x08, 0, 0xf81, 0);
> +	if (vendor_param == -1 || vendor_param & 0x02)
> +		return;
> +
> +	/* enable DP1.2 mode */
> +	vendor_param |= 0x02;
> +	snd_hda_codec_read(codec, 0x08, 0, 0x781, vendor_param);

Hi,

When trying to get Haswell HDMI audio working, I discovered that this 
verb when executed can get pins to change state from D0 to D3.

As the fixup is executed after hda_call_codec_resume this means that the 
pins will remain in D3. I'm not entirely sure of this, but I think we 
have no runtime power transitions if we are on AC power, so this could 
potentially be for a very long time.

> +	/* override 3 pins connection list */
> +	snd_hda_override_conn_list(codec, 0x05, 3, list);
> +	snd_hda_override_conn_list(codec, 0x06, 3, list);
> +	snd_hda_override_conn_list(codec, 0x07, 3, list);

So before the DP 1.2 verb is executed, the connections are
just 5 -> 2, 6 -> 3, 7 -> 4, but afterwards, every pin node can connect 
to every cvt node, and connection select verbs must change as a result?


-- 
David Henningsson, Canonical Ltd.
https://launchpad.net/~diwic