[Intel-gfx] [RFC 4/4] drm/i915/display: Initialize and compute HDMI Audio source cap

[Mitul Golani]

Initialize the audio capabilities for HDMI by setting them to their
maximum supported values and then call a function to compute these
capabilities into SADs. The audio capabilities for HDMI include
parameters such as supported frequency and channel configurations.
By computing these capabilities into SADs, we can determine which
audio formats are supported.

Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani at intel.com>
---
 drivers/gpu/drm/i915/display/intel_hdmi.c | 37 +++++++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_hdmi.h |  1 +
 2 files changed, 38 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_hdmi.c b/drivers/gpu/drm/i915/display/intel_hdmi.c
index aa822ee5fbda..c71110a1a44a 100644
--- a/drivers/gpu/drm/i915/display/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/display/intel_hdmi.c
@@ -2277,6 +2277,40 @@ bool intel_hdmi_compute_has_hdmi_sink(struct intel_encoder *encoder,
 		!intel_hdmi_is_cloned(crtc_state);
 }
 
+static unsigned int calc_audio_bw(int channel, int frequency)
+{
+	int bits_per_sample = 32;
+	unsigned int bandwidth = channel * frequency * bits_per_sample;
+	return bandwidth;
+}
+
+void
+intel_hdmi_audio_compute_config(struct intel_crtc_state *pipe_config)
+{
+	struct drm_display_mode *adjusted_mode = &pipe_config->hw.adjusted_mode;
+	int num_of_channel, aud_rates[7] = {192000, 176000, 96000, 88000, 48000, 44100, 32000};
+	unsigned int audio_req_bandwidth, available_blank_bandwidth, vblank, hblank;
+
+	hblank = adjusted_mode->htotal - adjusted_mode->hdisplay;
+	vblank = adjusted_mode->vtotal - adjusted_mode->vdisplay;
+	available_blank_bandwidth = hblank * vblank *
+				    drm_mode_vrefresh(adjusted_mode) * pipe_config->pipe_bpp;
+	for (num_of_channel = 8; num_of_channel > 0; num_of_channel--) {
+		for (int index = 0; index < 7; index++) {
+			audio_req_bandwidth = calc_audio_bw(num_of_channel,
+							    aud_rates[index]);
+			if (audio_req_bandwidth < available_blank_bandwidth) {
+				pipe_config->audio_config.max_frequency = aud_rates[index];
+				pipe_config->audio_config.max_channel = num_of_channel;
+				return;
+			}
+		}
+	}
+
+	pipe_config->audio_config.max_frequency = 0;
+	pipe_config->audio_config.max_channel = 0;
+}
+
 int intel_hdmi_compute_config(struct intel_encoder *encoder,
 			      struct intel_crtc_state *pipe_config,
 			      struct drm_connector_state *conn_state)
@@ -2344,6 +2378,7 @@ int intel_hdmi_compute_config(struct intel_encoder *encoder,
 			pipe_config->hdmi_high_tmds_clock_ratio = true;
 		}
 	}
+	intel_hdmi_audio_compute_config(pipe_config);
 
 	intel_hdmi_compute_gcp_infoframe(encoder, pipe_config,
 					 conn_state);
@@ -2368,6 +2403,8 @@ int intel_hdmi_compute_config(struct intel_encoder *encoder,
 		return -EINVAL;
 	}
 
+	intel_audio_compute_eld(pipe_config);
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/i915/display/intel_hdmi.h b/drivers/gpu/drm/i915/display/intel_hdmi.h
index 6b39df38d57a..6df303daf348 100644
--- a/drivers/gpu/drm/i915/display/intel_hdmi.h
+++ b/drivers/gpu/drm/i915/display/intel_hdmi.h
@@ -27,6 +27,7 @@ void intel_hdmi_init_connector(struct intel_digital_port *dig_port,
 bool intel_hdmi_compute_has_hdmi_sink(struct intel_encoder *encoder,
 				      const struct intel_crtc_state *crtc_state,
 				      const struct drm_connector_state *conn_state);
+void intel_hdmi_audio_compute_config(struct intel_crtc_state *pipe_config);
 int intel_hdmi_compute_config(struct intel_encoder *encoder,
 			      struct intel_crtc_state *pipe_config,
 			      struct drm_connector_state *conn_state);
-- 
2.25.1