[PATCH 2/2] drm/i915/audio: Populate ELD Port_ID

[Kai Vehmanen]

i915 never fills in the ELD Port_ID field, so it is always zero, and
the ELDs of identical monitors connected to different outputs are
byte-identical. Userspace then cannot tell which HDMI/DP PCM belongs to
which DRM connector without toggling the connector audio property.

Use drm_eld_set_port_id() when computing the audio config, so the value
reaches the audio driver through every path: the audio component
get_eld() callback, the hardware ELD buffer, SDVO and LPE audio.

The value is fixed for the lifetime of the connector, so it does not
cause extra audio re-enables when the ELD is compared across commits,
and state readout stays consistent because it is copied from the
programmed ELD.

Link: https://gitlab.freedesktop.org/drm/i915/kernel/-/work_items/16693
Signed-off-by: Kai Vehmanen <kai.vehmanen@xxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/i915/display/intel_audio.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_audio.c b/drivers/gpu/drm/i915/display/intel_audio.c
index 32f8c5e55319..3277e67748ee 100644
--- a/drivers/gpu/drm/i915/display/intel_audio.c
+++ b/drivers/gpu/drm/i915/display/intel_audio.c
@@ -881,6 +881,8 @@ bool intel_audio_compute_config(struct intel_encoder *encoder,
 	crtc_state->eld[6] = drm_av_sync_delay(connector, adjusted_mode) / 2;
 	mutex_unlock(&connector->eld_mutex);
 
+	drm_eld_set_port_id(crtc_state->eld, connector);
+
 	return true;
 }
 
-- 
2.43.0