drivers/gpu/drm/amd/display/dc/dce/dce_audio.c

Source file repositories/reference/linux-study-clean/drivers/gpu/drm/amd/display/dc/dce/dce_audio.c

File Facts

System
Linux kernel
Corpus path
drivers/gpu/drm/amd/display/dc/dce/dce_audio.c
Extension
.c
Size
36884 bytes
Lines
1257
Domain
Driver Families
Bucket
drivers/gpu
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct dp_audio_layout_config {
	uint8_t layouts_per_sample_denom;
	uint8_t symbols_per_layout;
	uint8_t max_layouts_per_audio_sdp;
};

static void get_audio_layout_config(
	uint32_t channel_count,
	enum dp_link_encoding encoding,
	struct dp_audio_layout_config *output)
{
	/* Assuming L-PCM audio. Current implementation uses max 1 layout per SDP,
	 * with each layout being the same size (8ch layout).
	 */
	if (encoding == DP_8b_10b_ENCODING) {
		if (channel_count == 2) {
			output->layouts_per_sample_denom = 4;
			output->symbols_per_layout = 40;
			output->max_layouts_per_audio_sdp = 1;
		} else if (channel_count == 8 || channel_count == 6) {
			output->layouts_per_sample_denom = 1;
			output->symbols_per_layout = 40;
			output->max_layouts_per_audio_sdp = 1;
		}
	} else if (encoding == DP_128b_132b_ENCODING) {
		if (channel_count == 2) {
			output->layouts_per_sample_denom = 4;
			output->symbols_per_layout = 10;
			output->max_layouts_per_audio_sdp = 1;
		} else if (channel_count == 8 || channel_count == 6) {
			output->layouts_per_sample_denom = 1;
			output->symbols_per_layout = 10;
			output->max_layouts_per_audio_sdp = 1;
		}
	}
}

static uint32_t get_av_stream_map_lane_count(
	enum dp_link_encoding encoding,
	enum dc_lane_count lane_count,
	bool is_mst)
{
	uint32_t av_stream_map_lane_count = 0;

	if (encoding == DP_8b_10b_ENCODING) {
		if (!is_mst)
			av_stream_map_lane_count = lane_count;
		else
			av_stream_map_lane_count = 4;
	} else if (encoding == DP_128b_132b_ENCODING) {
		av_stream_map_lane_count = 4;
	}

	ASSERT(av_stream_map_lane_count != 0);

	return av_stream_map_lane_count;
}

static uint32_t get_audio_sdp_overhead(
	enum dp_link_encoding encoding,
	enum dc_lane_count lane_count,
	bool is_mst)
{
	uint32_t audio_sdp_overhead = 0;

	if (encoding == DP_8b_10b_ENCODING) {
		if (is_mst)
			audio_sdp_overhead = 16; /* 4 * 2 + 8 */
		else
			audio_sdp_overhead = lane_count * 2 + 8;
	} else if (encoding == DP_128b_132b_ENCODING) {
		audio_sdp_overhead = 10; /* 4 x 2.5 */
	}

	ASSERT(audio_sdp_overhead != 0);

	return audio_sdp_overhead;
}

static uint32_t calculate_required_audio_bw_in_symbols(
	const struct audio_crtc_info *crtc_info,
	const struct dp_audio_layout_config *layout_config,
	uint32_t channel_count,
	uint32_t sample_rate_hz,
	uint32_t av_stream_map_lane_count,
	uint32_t audio_sdp_overhead)
{
	(void)channel_count;
	/* DP spec recommends between 1.05 to 1.1 safety margin to prevent sample under-run */
	struct fixed31_32 audio_sdp_margin = dc_fixpt_from_fraction(110, 100);

Annotation

Implementation Notes