[PATCH 3/3] drm/i915/display: Configure and initialize HDMI audio capabilities
Mitul Golani
mitulkumar.ajitkumar.golani at intel.com
Wed Sep 6 15:52:51 UTC 2023
Initialize the source audio capabilities in the `intel_crtc_state`
structure, setting them to their maximum supported values for
`max_channel` and `max_rate`. This initialization enables the
calculation of audio source capabilities concerning the available
mode bandwidth. These capabilities encompass parameters such as
supported rate and channel configurations.
Additionally, introduce a wrapper function for computing
Short Audio Descriptors (SADs). The wrapper function incorporates
logic for determining supported rates and channels according to the
capabilities of the audio source. It returns a set of SADs that are
compatible with the audio source's capabilities.
--v1:
- Refactor `max_channel` and `max_rate` to this commit as they are
being initialized here.
- Remove the call for `intel_audio_compute_eld` to avoid any regression
while merging. Instead, call it in a different commit when it is defined.
- Use `int` instead of `unsigned int` for `max_channel` and
`max_frequency`.
- Update commit message and header.
--v2:
- Use signed instead of unsigned variables.
- Avoid using magic numbers and give them proper names.
--v3:
- Move defines to intel_audio.c.
- Use consistent naming convention for rate and channel.
- Declare `num_of_channel` and `aud_rate` separately.
- Declare the index value outside of the for loop.
- Move Bandwidth calculation to intel_Audio.c as it is common for both
DP and HDMI. Also use `static`.
--v10:
- Merged patch 2 and 3 to deduplicate function calls.
- Instead of using Calibrate and calculated functions separately,
removed code duplication and merged functions. [Nikula, Jani]
- Remove magic value for SAD Channel mask. [Nikula, Jani]
- Corrected rate values based on HDMI Spec [Nikula, Jani]
- Update drm function to extract SAD from ELD [Nikula, Jani]
Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani at intel.com>
---
drivers/gpu/drm/i915/display/intel_audio.c | 126 ++++++++++++++++++
.../drm/i915/display/intel_display_types.h | 6 +
2 files changed, 132 insertions(+)
diff --git a/drivers/gpu/drm/i915/display/intel_audio.c b/drivers/gpu/drm/i915/display/intel_audio.c
index 94342da8c515..38438ef9c649 100644
--- a/drivers/gpu/drm/i915/display/intel_audio.c
+++ b/drivers/gpu/drm/i915/display/intel_audio.c
@@ -64,6 +64,11 @@
* struct &i915_audio_component_audio_ops @audio_ops is called from i915 driver.
*/
+#define AUDIO_SAMPLE_CONTAINER_SIZE 32
+#define MAX_CHANNEL_COUNT 8
+#define ELD_SAD_CHANNELS_MASK 0x7
+#define NUM_SAMPLE_FREQUENCIES 7
+
struct intel_audio_funcs {
void (*audio_codec_enable)(struct intel_encoder *encoder,
const struct intel_crtc_state *crtc_state,
@@ -770,6 +775,124 @@ void intel_audio_sdp_split_update(const struct intel_crtc_state *crtc_state)
crtc_state->sdp_split_enable ? AUD_ENABLE_SDP_SPLIT : 0);
}
+static int sad_to_channels(const u8 *sad)
+{
+ return 1 + (sad[0] & ELD_SAD_CHANNELS_MASK);
+}
+
+static void calculate_max_rate_and_channel(struct intel_crtc_state *pipe_config,
+ int channel_count, int *rate,
+ int available_blank_bandwidth)
+{
+ int index;
+
+ for (index = 0; index < NUM_SAMPLE_FREQUENCIES; index++) {
+ int audio_req_bandwidth = channel_count *
+ rate[index] * AUDIO_SAMPLE_CONTAINER_SIZE;
+
+ if (audio_req_bandwidth < available_blank_bandwidth) {
+ pipe_config->audio.max_rate = rate[index];
+ pipe_config->audio.max_channel_count = channel_count;
+ return;
+ }
+ }
+}
+
+static void calc_and_calibrate_audio_config_params(struct intel_crtc_state *pipe_config,
+ int channel, int *rate,
+ bool calibration_required)
+{
+ struct drm_display_mode *adjusted_mode = &pipe_config->hw.adjusted_mode;
+ int 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;
+
+ /*
+ * Expected calibration of channels and respective rates,
+ * based on MAX_CHANNEL_COUNT. First calculate channel and
+ * rate based on maximum that source can compute, later
+ * with respect to sink's maximum channel capacity, calibrate
+ * supported rates.
+ */
+ if (calibration_required) {
+ calculate_max_rate_and_channel(pipe_config, channel,
+ rate, available_blank_bandwidth);
+ } else {
+ for (int channel_count = channel; channel_count > 0; channel_count--) {
+ calculate_max_rate_and_channel(pipe_config, channel_count,
+ rate, available_blank_bandwidth);
+
+ // Check if a suitable configuration is found and exit the loop
+ if (pipe_config->audio.max_rate != 0)
+ break;
+ }
+ }
+}
+
+static int get_supported_freq_mask(struct intel_crtc_state *crtc_state, int *rate)
+{
+ int mask = 0, index;
+
+ for (index = NUM_SAMPLE_FREQUENCIES - 1; index >= 0; index--) {
+ if (rate[index] > crtc_state->audio.max_rate)
+ break;
+ mask |= 1 << index;
+ }
+
+ return mask;
+}
+
+static int intel_audio_compute_eld(struct intel_crtc_state *crtc_state)
+{
+ struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev);
+ //Audio Sample Frequency Based on DP 2.1 spec Table 2-112
+ int rate[NUM_SAMPLE_FREQUENCIES] = {192000, 176400, 96000, 88200, 48000, 44100, 32000};
+ u8 *eld, *sad;
+ int index, mask = 0;
+
+ eld = crtc_state->eld;
+ if (!eld)
+ return -EINVAL;
+
+ sad = drm_extract_sad_from_eld(eld);
+ if (!sad)
+ return -ENODATA;
+
+ calc_and_calibrate_audio_config_params(crtc_state, MAX_CHANNEL_COUNT,
+ rate, false);
+
+ mask = get_supported_freq_mask(crtc_state, rate);
+ for (index = 0; index < drm_eld_sad_count(eld); index++, sad += 3) {
+ /*
+ * Respect source restricitions. Limit capabilities to a subset that is
+ * supported both by the source and the sink.
+ */
+ if (sad_to_channels(sad) >= crtc_state->audio.max_channel_count) {
+ sad[0] &= ~ELD_SAD_CHANNELS_MASK;
+ sad[0] |= crtc_state->audio.max_channel_count - 1;
+ drm_dbg_kms(&i915->drm, "Channel count is limited to %d\n",
+ crtc_state->audio.max_channel_count - 1);
+ } else {
+ /*
+ * calibrate rate when, sink supported channel
+ * count is slight less than max supported
+ * channel count.
+ */
+ calc_and_calibrate_audio_config_params(crtc_state,
+ sad_to_channels(sad), rate,
+ true);
+ mask = get_supported_freq_mask(crtc_state, rate);
+ }
+
+ sad[1] &= mask;
+ }
+
+ return 0;
+}
+
bool intel_audio_compute_config(struct intel_encoder *encoder,
struct intel_crtc_state *crtc_state,
struct drm_connector_state *conn_state)
@@ -791,6 +914,9 @@ bool intel_audio_compute_config(struct intel_encoder *encoder,
crtc_state->eld[6] = drm_av_sync_delay(connector, adjusted_mode) / 2;
+ if (intel_audio_compute_eld(crtc_state))
+ return false;
+
return true;
}
diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index 539bca0fdebb..652d5f610188 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -1131,6 +1131,12 @@ struct intel_crtc_state {
struct {
bool has_audio;
+
+ /* Audio rate in Hz */
+ int max_rate;
+
+ /* Number of audio channels */
+ int max_channel_count;
} audio;
/*
--
2.25.1
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