ALSA: hda/hdmi: expose ELD control

Applications may want to read ELD information to
understand what codecs are supported on the HDMI
receiver and handle the a-v delay for better lip-sync.

ELD information is exposed in a device-specific
IFACE_PCM kcontrol. Tested both with amixer and
PulseAudio; with a corresponding patch passthrough modes
are enabled automagically.

ELD control size is set to zero in case of errors or
wrong configurations. No notifications are implemented
for now, it is expected that jack detection is used to
reconfigure the audio outputs.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 8 insertions, 5 deletions

diff --git a/sound/pci/hda/hda_eld.c b/sound/pci/hda/hda_eld.c
index c34f730f4815..f1c621d2f8e8 100644
--- a/sound/pci/hda/hda_eld.c
+++ b/sound/pci/hda/hda_eld.c
@@ -318,6 +318,11 @@ int snd_hdmi_get_eld(struct hdmi_eld *eld,
 	int size;
 	unsigned char *buf;
 
+	/*
+	 * ELD size is initialized to zero in caller function. If no errors and
+	 * ELD is valid, actual eld_size is assigned in hdmi_update_eld()
+	 */
+
 	if (!eld->eld_valid)
 		return -ENOENT;
 
@@ -327,14 +332,13 @@ int snd_hdmi_get_eld(struct hdmi_eld *eld,
 		snd_printd(KERN_INFO "HDMI: ELD buf size is 0, force 128\n");
 		size = 128;
 	}
-	if (size < ELD_FIXED_BYTES || size > PAGE_SIZE) {
+	if (size < ELD_FIXED_BYTES || size > ELD_MAX_SIZE) {
 		snd_printd(KERN_INFO "HDMI: invalid ELD buf size %d\n", size);
 		return -ERANGE;
 	}
 
-	buf = kmalloc(size, GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
+	/* set ELD buffer */
+	buf = eld->eld_buffer;
 
 	for (i = 0; i < size; i++) {
 		unsigned int val = hdmi_get_eld_data(codec, nid, i);
@@ -356,7 +360,6 @@ int snd_hdmi_get_eld(struct hdmi_eld *eld,
 	ret = hdmi_update_eld(eld, buf, size);
 
 error:
-	kfree(buf);
 	return ret;
 }