diff options
Diffstat (limited to 'drivers/gpu/drm/display/drm_hdmi_helper.c')
| -rw-r--r-- | drivers/gpu/drm/display/drm_hdmi_helper.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/drivers/gpu/drm/display/drm_hdmi_helper.c b/drivers/gpu/drm/display/drm_hdmi_helper.c index 74dd4d01dd9b..855cb02b827d 100644 --- a/drivers/gpu/drm/display/drm_hdmi_helper.c +++ b/drivers/gpu/drm/display/drm_hdmi_helper.c @@ -256,3 +256,171 @@ drm_hdmi_compute_mode_clock(const struct drm_display_mode *mode, return DIV_ROUND_CLOSEST_ULL(clock * bpc, 8); } EXPORT_SYMBOL(drm_hdmi_compute_mode_clock); + +struct drm_hdmi_acr_n_cts_entry { + unsigned int n; + unsigned int cts; +}; + +struct drm_hdmi_acr_data { + unsigned long tmds_clock_khz; + struct drm_hdmi_acr_n_cts_entry n_cts_32k, + n_cts_44k1, + n_cts_48k; +}; + +static const struct drm_hdmi_acr_data hdmi_acr_n_cts[] = { + { + /* "Other" entry */ + .n_cts_32k = { .n = 4096, }, + .n_cts_44k1 = { .n = 6272, }, + .n_cts_48k = { .n = 6144, }, + }, { + .tmds_clock_khz = 25175, + .n_cts_32k = { .n = 4576, .cts = 28125, }, + .n_cts_44k1 = { .n = 7007, .cts = 31250, }, + .n_cts_48k = { .n = 6864, .cts = 28125, }, + }, { + .tmds_clock_khz = 25200, + .n_cts_32k = { .n = 4096, .cts = 25200, }, + .n_cts_44k1 = { .n = 6272, .cts = 28000, }, + .n_cts_48k = { .n = 6144, .cts = 25200, }, + }, { + .tmds_clock_khz = 27000, + .n_cts_32k = { .n = 4096, .cts = 27000, }, + .n_cts_44k1 = { .n = 6272, .cts = 30000, }, + .n_cts_48k = { .n = 6144, .cts = 27000, }, + }, { + .tmds_clock_khz = 27027, + .n_cts_32k = { .n = 4096, .cts = 27027, }, + .n_cts_44k1 = { .n = 6272, .cts = 30030, }, + .n_cts_48k = { .n = 6144, .cts = 27027, }, + }, { + .tmds_clock_khz = 54000, + .n_cts_32k = { .n = 4096, .cts = 54000, }, + .n_cts_44k1 = { .n = 6272, .cts = 60000, }, + .n_cts_48k = { .n = 6144, .cts = 54000, }, + }, { + .tmds_clock_khz = 54054, + .n_cts_32k = { .n = 4096, .cts = 54054, }, + .n_cts_44k1 = { .n = 6272, .cts = 60060, }, + .n_cts_48k = { .n = 6144, .cts = 54054, }, + }, { + .tmds_clock_khz = 74176, + .n_cts_32k = { .n = 11648, .cts = 210937, }, /* and 210938 */ + .n_cts_44k1 = { .n = 17836, .cts = 234375, }, + .n_cts_48k = { .n = 11648, .cts = 140625, }, + }, { + .tmds_clock_khz = 74250, + .n_cts_32k = { .n = 4096, .cts = 74250, }, + .n_cts_44k1 = { .n = 6272, .cts = 82500, }, + .n_cts_48k = { .n = 6144, .cts = 74250, }, + }, { + .tmds_clock_khz = 148352, + .n_cts_32k = { .n = 11648, .cts = 421875, }, + .n_cts_44k1 = { .n = 8918, .cts = 234375, }, + .n_cts_48k = { .n = 5824, .cts = 140625, }, + }, { + .tmds_clock_khz = 148500, + .n_cts_32k = { .n = 4096, .cts = 148500, }, + .n_cts_44k1 = { .n = 6272, .cts = 165000, }, + .n_cts_48k = { .n = 6144, .cts = 148500, }, + }, { + .tmds_clock_khz = 296703, + .n_cts_32k = { .n = 5824, .cts = 421875, }, + .n_cts_44k1 = { .n = 4459, .cts = 234375, }, + .n_cts_48k = { .n = 5824, .cts = 281250, }, + }, { + .tmds_clock_khz = 297000, + .n_cts_32k = { .n = 3072, .cts = 222750, }, + .n_cts_44k1 = { .n = 4704, .cts = 247500, }, + .n_cts_48k = { .n = 5120, .cts = 247500, }, + }, { + .tmds_clock_khz = 593407, + .n_cts_32k = { .n = 5824, .cts = 843750, }, + .n_cts_44k1 = { .n = 8918, .cts = 937500, }, + .n_cts_48k = { .n = 5824, .cts = 562500, }, + }, { + .tmds_clock_khz = 594000, + .n_cts_32k = { .n = 3072, .cts = 445500, }, + .n_cts_44k1 = { .n = 9408, .cts = 990000, }, + .n_cts_48k = { .n = 6144, .cts = 594000, }, + }, +}; + +static int drm_hdmi_acr_find_tmds_entry(unsigned long tmds_clock_khz) +{ + int i; + + /* skip the "other" entry */ + for (i = 1; i < ARRAY_SIZE(hdmi_acr_n_cts); i++) { + if (hdmi_acr_n_cts[i].tmds_clock_khz == tmds_clock_khz) + return i; + } + + return 0; +} + +/** + * drm_hdmi_acr_get_n_cts() - get N and CTS values for Audio Clock Regeneration + * + * @tmds_char_rate: TMDS clock (char rate) as used by the HDMI connector + * @sample_rate: audio sample rate + * @out_n: a pointer to write the N value + * @out_cts: a pointer to write the CTS value + * + * Get the N and CTS values (either by calculating them or by returning data + * from the tables. This follows the HDMI 1.4b Section 7.2 "Audio Sample Clock + * Capture and Regeneration". + * + * Note, @sample_rate corresponds to the Fs value, see sections 7.2.4 - 7.2.6 + * on how to select Fs for non-L-PCM formats. + */ +void +drm_hdmi_acr_get_n_cts(unsigned long long tmds_char_rate, + unsigned int sample_rate, + unsigned int *out_n, + unsigned int *out_cts) +{ + /* be a bit more tolerant, especially for the 1.001 entries */ + unsigned long tmds_clock_khz = DIV_ROUND_CLOSEST_ULL(tmds_char_rate, 1000); + const struct drm_hdmi_acr_n_cts_entry *entry; + unsigned int n, cts, mult; + int tmds_idx; + + tmds_idx = drm_hdmi_acr_find_tmds_entry(tmds_clock_khz); + + /* + * Don't change the order, 192 kHz is divisible by 48k and 32k, but it + * should use 48k entry. + */ + if (sample_rate % 48000 == 0) { + entry = &hdmi_acr_n_cts[tmds_idx].n_cts_48k; + mult = sample_rate / 48000; + } else if (sample_rate % 44100 == 0) { + entry = &hdmi_acr_n_cts[tmds_idx].n_cts_44k1; + mult = sample_rate / 44100; + } else if (sample_rate % 32000 == 0) { + entry = &hdmi_acr_n_cts[tmds_idx].n_cts_32k; + mult = sample_rate / 32000; + } else { + entry = NULL; + } + + if (entry) { + n = entry->n * mult; + cts = entry->cts; + } else { + /* Recommended optimal value, HDMI 1.4b, Section 7.2.1 */ + n = 128 * sample_rate / 1000; + cts = 0; + } + + if (!cts) + cts = DIV_ROUND_CLOSEST_ULL(tmds_char_rate * n, + 128 * sample_rate); + + *out_n = n; + *out_cts = cts; +} +EXPORT_SYMBOL(drm_hdmi_acr_get_n_cts); |