[PATCH RFC 4/4] ALSA: x86: Use common CEA channel allocations
From: Cássio Gabriel
Date: Fri Jun 12 2026 - 00:54:54 EST
Replace the Intel HDMI LPE copy of the CEA allocation table and selector
with the common PCM ELD helpers. Preserve the driver's existing limits:
only ELD speaker bits 0 through 6 participate, only CA values through
0x1f are considered, and an incompatible ELD does not use HDA's fallback.
Select SND_PCM_ELD for the new helper dependency.
Signed-off-by: Cássio Gabriel <cassiogabrielcontato@xxxxxxxxx>
---
sound/x86/Kconfig | 1 +
sound/x86/intel_hdmi_audio.c | 158 ++++++-------------------------------------
sound/x86/intel_hdmi_audio.h | 9 ---
3 files changed, 20 insertions(+), 148 deletions(-)
diff --git a/sound/x86/Kconfig b/sound/x86/Kconfig
index 4ffcc5e623c2..a990989a12b9 100644
--- a/sound/x86/Kconfig
+++ b/sound/x86/Kconfig
@@ -12,6 +12,7 @@ config HDMI_LPE_AUDIO
tristate "HDMI audio without HDAudio on Intel Atom platforms"
depends on DRM_I915
select SND_PCM
+ select SND_PCM_ELD
help
Choose this option to support HDMI LPE Audio mode
diff --git a/sound/x86/intel_hdmi_audio.c b/sound/x86/intel_hdmi_audio.c
index 91dfcf47e979..4ea29c3ea6c5 100644
--- a/sound/x86/intel_hdmi_audio.c
+++ b/sound/x86/intel_hdmi_audio.c
@@ -26,6 +26,7 @@
#include <sound/core.h>
#include <sound/asoundef.h>
#include <sound/pcm.h>
+#include <sound/pcm_drm_eld.h>
#include <sound/pcm_params.h>
#include <sound/initval.h>
#include <sound/control.h>
@@ -57,72 +58,6 @@ module_param(single_port, bool, 0444);
MODULE_PARM_DESC(single_port,
"Single-port mode (for compatibility)");
-/*
- * ELD SA bits in the CEA Speaker Allocation data block
- */
-static const int eld_speaker_allocation_bits[] = {
- [0] = FL | FR,
- [1] = LFE,
- [2] = FC,
- [3] = RL | RR,
- [4] = RC,
- [5] = FLC | FRC,
- [6] = RLC | RRC,
- /* the following are not defined in ELD yet */
- [7] = 0,
-};
-
-/*
- * This is an ordered list!
- *
- * The preceding ones have better chances to be selected by
- * hdmi_channel_allocation().
- */
-static struct cea_channel_speaker_allocation channel_allocations[] = {
-/* channel: 7 6 5 4 3 2 1 0 */
-{ .ca_index = 0x00, .speakers = { 0, 0, 0, 0, 0, 0, FR, FL } },
- /* 2.1 */
-{ .ca_index = 0x01, .speakers = { 0, 0, 0, 0, 0, LFE, FR, FL } },
- /* Dolby Surround */
-{ .ca_index = 0x02, .speakers = { 0, 0, 0, 0, FC, 0, FR, FL } },
- /* surround40 */
-{ .ca_index = 0x08, .speakers = { 0, 0, RR, RL, 0, 0, FR, FL } },
- /* surround41 */
-{ .ca_index = 0x09, .speakers = { 0, 0, RR, RL, 0, LFE, FR, FL } },
- /* surround50 */
-{ .ca_index = 0x0a, .speakers = { 0, 0, RR, RL, FC, 0, FR, FL } },
- /* surround51 */
-{ .ca_index = 0x0b, .speakers = { 0, 0, RR, RL, FC, LFE, FR, FL } },
- /* 6.1 */
-{ .ca_index = 0x0f, .speakers = { 0, RC, RR, RL, FC, LFE, FR, FL } },
- /* surround71 */
-{ .ca_index = 0x13, .speakers = { RRC, RLC, RR, RL, FC, LFE, FR, FL } },
-
-{ .ca_index = 0x03, .speakers = { 0, 0, 0, 0, FC, LFE, FR, FL } },
-{ .ca_index = 0x04, .speakers = { 0, 0, 0, RC, 0, 0, FR, FL } },
-{ .ca_index = 0x05, .speakers = { 0, 0, 0, RC, 0, LFE, FR, FL } },
-{ .ca_index = 0x06, .speakers = { 0, 0, 0, RC, FC, 0, FR, FL } },
-{ .ca_index = 0x07, .speakers = { 0, 0, 0, RC, FC, LFE, FR, FL } },
-{ .ca_index = 0x0c, .speakers = { 0, RC, RR, RL, 0, 0, FR, FL } },
-{ .ca_index = 0x0d, .speakers = { 0, RC, RR, RL, 0, LFE, FR, FL } },
-{ .ca_index = 0x0e, .speakers = { 0, RC, RR, RL, FC, 0, FR, FL } },
-{ .ca_index = 0x10, .speakers = { RRC, RLC, RR, RL, 0, 0, FR, FL } },
-{ .ca_index = 0x11, .speakers = { RRC, RLC, RR, RL, 0, LFE, FR, FL } },
-{ .ca_index = 0x12, .speakers = { RRC, RLC, RR, RL, FC, 0, FR, FL } },
-{ .ca_index = 0x14, .speakers = { FRC, FLC, 0, 0, 0, 0, FR, FL } },
-{ .ca_index = 0x15, .speakers = { FRC, FLC, 0, 0, 0, LFE, FR, FL } },
-{ .ca_index = 0x16, .speakers = { FRC, FLC, 0, 0, FC, 0, FR, FL } },
-{ .ca_index = 0x17, .speakers = { FRC, FLC, 0, 0, FC, LFE, FR, FL } },
-{ .ca_index = 0x18, .speakers = { FRC, FLC, 0, RC, 0, 0, FR, FL } },
-{ .ca_index = 0x19, .speakers = { FRC, FLC, 0, RC, 0, LFE, FR, FL } },
-{ .ca_index = 0x1a, .speakers = { FRC, FLC, 0, RC, FC, 0, FR, FL } },
-{ .ca_index = 0x1b, .speakers = { FRC, FLC, 0, RC, FC, LFE, FR, FL } },
-{ .ca_index = 0x1c, .speakers = { FRC, FLC, RR, RL, 0, 0, FR, FL } },
-{ .ca_index = 0x1d, .speakers = { FRC, FLC, RR, RL, 0, LFE, FR, FL } },
-{ .ca_index = 0x1e, .speakers = { FRC, FLC, RR, RL, FC, 0, FR, FL } },
-{ .ca_index = 0x1f, .speakers = { FRC, FLC, RR, RL, FC, LFE, FR, FL } },
-};
-
static const struct channel_map_table map_tables[] = {
{ SNDRV_CHMAP_FL, 0x00, FL },
{ SNDRV_CHMAP_FR, 0x01, FR },
@@ -384,68 +319,13 @@ static int had_init_audio_ctrl(struct snd_pcm_substream *substream,
return 0;
}
-/*
- * Compute derived values in channel_allocations[].
- */
-static void init_channel_allocations(void)
-{
- int i, j;
- struct cea_channel_speaker_allocation *p;
-
- for (i = 0; i < ARRAY_SIZE(channel_allocations); i++) {
- p = channel_allocations + i;
- p->channels = 0;
- p->spk_mask = 0;
- for (j = 0; j < ARRAY_SIZE(p->speakers); j++)
- if (p->speakers[j]) {
- p->channels++;
- p->spk_mask |= p->speakers[j];
- }
- }
-}
-
-/*
- * The transformation takes two steps:
- *
- * eld->spk_alloc => (eld_speaker_allocation_bits[]) => spk_mask
- * spk_mask => (channel_allocations[]) => ai->CA
- *
- * TODO: it could select the wrong CA from multiple candidates.
- */
static int had_channel_allocation(struct snd_intelhad *intelhaddata,
int channels)
{
- int i;
- int ca = 0;
- int spk_mask = 0;
-
- /*
- * CA defaults to 0 for basic stereo audio
- */
- if (channels <= 2)
- return 0;
-
- /*
- * expand ELD's speaker allocation mask
- *
- * ELD tells the speaker mask in a compact(paired) form,
- * expand ELD's notions to match the ones used by Audio InfoFrame.
- */
-
- for (i = 0; i < ARRAY_SIZE(eld_speaker_allocation_bits); i++) {
- if (intelhaddata->eld[DRM_ELD_SPEAKER] & (1 << i))
- spk_mask |= eld_speaker_allocation_bits[i];
- }
+ int ca;
- /* search for the first working match in the CA table */
- for (i = 0; i < ARRAY_SIZE(channel_allocations); i++) {
- if (channels == channel_allocations[i].channels &&
- (spk_mask & channel_allocations[i].spk_mask) ==
- channel_allocations[i].spk_mask) {
- ca = channel_allocations[i].ca_index;
- break;
- }
- }
+ ca = snd_cea_channel_allocation(intelhaddata->eld[DRM_ELD_SPEAKER] & 0x7f,
+ channels, 0x1f, false);
dev_dbg(intelhaddata->dev, "select CA 0x%x for %d\n", ca, channels);
@@ -487,7 +367,7 @@ static void had_build_channel_allocation_map(struct snd_intelhad *intelhaddata)
/*
* Sink may support more than 8 channels, if eld_high has more than
* one bit set. SOC supports max 8 channels.
- * Refer eld_speaker_allocation_bits, for sink speaker allocation
+ * Refer the CEA ELD speaker allocation mapping for sink allocation.
*/
/* if 0x2F < eld < 0x4F fall back to 0x2f, else fall back to 0x4F */
@@ -505,24 +385,25 @@ static void had_build_channel_allocation_map(struct snd_intelhad *intelhaddata)
}
}
- for (i = 0; i < ARRAY_SIZE(eld_speaker_allocation_bits); i++) {
- if (intelhaddata->eld[DRM_ELD_SPEAKER] & (1 << i))
- spk_mask |= eld_speaker_allocation_bits[i];
- }
+ spk_mask = snd_cea_spk_mask_from_alloc(intelhaddata->eld[DRM_ELD_SPEAKER] &
+ 0x7f);
- for (i = 0; i < ARRAY_SIZE(channel_allocations); i++) {
- if (spk_mask == channel_allocations[i].spk_mask) {
- for (c = 0; c < channel_allocations[i].channels; c++) {
- chmap->map[c] = spk_to_chmap(
- channel_allocations[i].speakers[
- (MAX_SPEAKERS - 1) - c]);
- }
- chmap->channels = channel_allocations[i].channels;
+ for (i = 0; i < snd_cea_channel_allocations_count; i++) {
+ const struct snd_cea_channel_speaker_allocation *ca;
+
+ ca = &snd_cea_channel_allocations[i];
+ if (ca->ca_index > 0x1f)
+ continue;
+ if (spk_mask == ca->spk_mask) {
+ for (c = 0; c < ca->channels; c++)
+ chmap->map[c] =
+ spk_to_chmap(ca->speakers[MAX_SPEAKERS - 1 - c]);
+ chmap->channels = ca->channels;
intelhaddata->chmap->chmap = chmap;
break;
}
}
- if (i >= ARRAY_SIZE(channel_allocations))
+ if (i >= snd_cea_channel_allocations_count)
kfree(chmap);
}
@@ -1723,7 +1604,6 @@ static int __hdmi_lpe_audio_probe(struct platform_device *pdev)
if (ret)
return ret;
- init_channel_allocations();
card_ctx->num_pipes = pdata->num_pipes;
card_ctx->num_ports = single_port ? 1 : pdata->num_ports;
diff --git a/sound/x86/intel_hdmi_audio.h b/sound/x86/intel_hdmi_audio.h
index 88bf9ef2c491..21cec605a879 100644
--- a/sound/x86/intel_hdmi_audio.h
+++ b/sound/x86/intel_hdmi_audio.h
@@ -44,15 +44,6 @@ enum cea_speaker_placement {
LFE = (1 << 10), /* Low Frequency Effect */
};
-struct cea_channel_speaker_allocation {
- int ca_index;
- int speakers[8];
-
- /* derived values, just for convenience */
- int channels;
- int spk_mask;
-};
-
struct channel_map_table {
unsigned char map; /* ALSA API channel map position */
unsigned char cea_slot; /* CEA slot value */
--
2.54.0