ALSA: hda - Restrict PCM parameters per ELD information over HDMI

When a device is plugged over HDMI, it passes some information in ELD
including the supported PCM parameters like formats, rates, channels.
This patch adds the check to PCM open callback of HDMI streams so that
only valid parameters the device supports are used.

When no device is plugged, the parameters the codec supports are used;
it's mostly all parameters the hardware can work.  This is for apps
that are started before device plugging and do probing (e.g. a sound
daemon), so that at least, probing would work even before the device
plugging.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 49 insertions, 0 deletions

diff --git a/sound/pci/hda/hda_eld.c b/sound/pci/hda/hda_eld.c
index d8da18a9e98b..803b298f7411 100644
--- a/sound/pci/hda/hda_eld.c
+++ b/sound/pci/hda/hda_eld.c
@@ -596,4 +596,53 @@ void snd_hda_eld_proc_free(struct hda_codec *codec, struct hdmi_eld *eld)
 }
 EXPORT_SYMBOL_HDA(snd_hda_eld_proc_free);
 
+/* update PCM info based on ELD */
+void hdmi_eld_update_pcm_info(struct hdmi_eld *eld, struct hda_pcm_stream *pcm,
+                              struct hda_pcm_stream *codec_pars)
+{
+        int i;
+
+        pcm->rates = 0;
+        pcm->formats = 0;
+        pcm->maxbps = 0;
+        pcm->channels_min = -1;
+        pcm->channels_max = 0;
+        for (i = 0; i < eld->sad_count; i++) {
+                struct cea_sad *a = &eld->sad[i];
+                pcm->rates |= a->rates;
+                if (a->channels < pcm->channels_min)
+                        pcm->channels_min = a->channels;
+                if (a->channels > pcm->channels_max)
+                        pcm->channels_max = a->channels;
+                if (a->format == AUDIO_CODING_TYPE_LPCM) {
+                        if (a->sample_bits & AC_SUPPCM_BITS_16) {
+                                pcm->formats |= SNDRV_PCM_FMTBIT_S16_LE;
+                                if (pcm->maxbps < 16)
+                                        pcm->maxbps = 16;
+                        }
+                        if (a->sample_bits & AC_SUPPCM_BITS_20) {
+                                pcm->formats |= SNDRV_PCM_FMTBIT_S32_LE;
+                                if (pcm->maxbps < 20)
+                                        pcm->maxbps = 20;
+                        }
+                        if (a->sample_bits & AC_SUPPCM_BITS_24) {
+                                pcm->formats |= SNDRV_PCM_FMTBIT_S32_LE;
+                                if (pcm->maxbps < 24)
+                                        pcm->maxbps = 24;
+                        }
+                }
+        }
+
+        if (!codec_pars)
+                return;
+
+        /* restrict the parameters by the values the codec provides */
+        pcm->rates &= codec_pars->rates;
+        pcm->formats &= codec_pars->formats;
+        pcm->channels_min = max(pcm->channels_min, codec_pars->channels_min);
+        pcm->channels_max = min(pcm->channels_max, codec_pars->channels_max);
+        pcm->maxbps = min(pcm->maxbps, codec_pars->maxbps);
+}
+EXPORT_SYMBOL_HDA(hdmi_eld_update_pcm_info);
+
 #endif /* CONFIG_PROC_FS */