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Commit a5666824 authored by Anssi Hannula's avatar Anssi Hannula Committed by Takashi Iwai
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ALSA: hda - hdmi: Skip out-of-range latency values in AMD ELD generator 



The ATI/AMD video/audio latencies are specified in apparent HDMI VSDB
format. In this format values above 251 are not valid (or stream
component is not supported - 255), but no checking is performed since
this was not mentioned in the AMD HDA verbs specification.

Check that the latencies are valid before using them, and add a comment
describing the formats.

Signed-off-by: default avatarAnssi Hannula <anssi.hannula@iki.fi>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 13122e6e

sound/pci/hda/hda_eld.c

+19 −4
Original line number Diff line number Diff line
@@ -768,13 +768,28 @@ int snd_hdmi_get_eld_ati(struct hda_codec *codec, hda_nid_t nid, 
		return -EINVAL;

	}



	/*

	 * HDMI VSDB latency format:

	 * separately for both audio and video:

	 *  0          field not valid or unknown latency

	 *  [1..251]   msecs = (x-1)*2  (max 500ms with x = 251 = 0xfb)

	 *  255        audio/video not supported

	 *

	 * HDA latency format:

	 * single value indicating video latency relative to audio:

	 *  0          unknown or 0ms

	 *  [1..250]   msecs = x*2  (max 500ms with x = 250 = 0xfa)

	 *  [251..255] reserved

	 */

	aud_synch = snd_hda_codec_read(codec, nid, 0, ATI_VERB_GET_AUDIO_VIDEO_DELAY, 0);

	if ((aud_synch & ATI_DELAY_VIDEO_LATENCY) && (aud_synch & ATI_DELAY_AUDIO_LATENCY)) {

		int video_latency = (aud_synch & ATI_DELAY_VIDEO_LATENCY) - 1;

		int audio_latency = ((aud_synch & ATI_DELAY_AUDIO_LATENCY) >> 8) - 1;

		int video_latency_hdmi = (aud_synch & ATI_DELAY_VIDEO_LATENCY);

		int audio_latency_hdmi = (aud_synch & ATI_DELAY_AUDIO_LATENCY) >> 8;



		if (video_latency > audio_latency)

			buf[6] = min(video_latency - audio_latency, 0xfa);

		if (video_latency_hdmi <= 0xfb && audio_latency_hdmi <= 0xfb &&

		    video_latency_hdmi > audio_latency_hdmi)

			buf[6] = video_latency_hdmi - audio_latency_hdmi;

		/* else unknown/invalid or 0ms or video ahead of audio, so use zero */

	}



	/* Baseline length */