Add helper functions to compute HDMI CTS and N parameters. Implementation is based on HDMI 1.4b specification.
Signed-off-by: Arnaud Pouliquen arnaud.pouliquen@st.com Acked-by: Benjamin Gaignard benjamin.gaignard@linaro.org Acked-by: Vincent ABRIOU vincent.abriou@st.com --- drivers/video/hdmi.c | 208 +++++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/hdmi.h | 24 ++++++ 2 files changed, 232 insertions(+)
diff --git a/drivers/video/hdmi.c b/drivers/video/hdmi.c index 1626892..5d124ef 100644 --- a/drivers/video/hdmi.c +++ b/drivers/video/hdmi.c @@ -1242,3 +1242,211 @@ int hdmi_infoframe_unpack(union hdmi_infoframe *frame, void *buffer) return ret; } EXPORT_SYMBOL(hdmi_infoframe_unpack); + +/* + * audio clock regeneration (acr) parameters + * N and CTS computation are based on HDMI specification 1.4b + */ +enum hdmi_audio_rate { + HDMI_AUDIO_N_CTS_32KHZ, + HDMI_AUDIO_N_CTS_44_1KHZ, + HDMI_AUDIO_N_CTS_48KHZ, +}; + +struct hdmi_audio_acr { + unsigned int tmds_clk; + struct hdmi_audio_n_cts n_cts; +}; + +static const struct hdmi_audio_acr hdmi_audio_standard_acr[3][13] = { + [HDMI_AUDIO_N_CTS_32KHZ] = { + /* N and CTS values for 32 kHz rate*/ + { 25174825, { 4576, 28125, 0 } }, /* 25.20/1.001 MHz */ + { 25200000, { 4096, 25200, 0 } }, /* 25.20 MHz */ + { 27000000, { 4096, 27000, 0 } }, /* 27.00 MHz */ + { 27027000, { 4096, 27027, 0 } }, /* 27.00*1.001 MHz */ + { 54000000, { 4096, 54000, 0 } }, /* 54.00 MHz */ + { 54054000, { 4096, 54054, 0 } }, /* 54.00*1.001 MHz */ + { 74175824, { 11648, 210937, 50 } }, /* 74.25/1.001 MHz */ + { 74250000, { 4096, 74250, 0 } }, /* 74.25 MHz */ + { 148351648, { 11648, 421875, 0 } }, /* 148.50/1.001 MHz */ + { 148500000, { 4096, 148500, 0 } }, /* 148.50 MHz */ + { 296703296, { 5824, 421875, 0 } }, /* 297/1.001 MHz (truncated)*/ + { 296703297, { 5824, 421875, 0 } }, /* 297/1.001 MHz (rounded)*/ + { 297000000, { 3072, 222750, 0 } }, /* 297 MHz */ + }, + [HDMI_AUDIO_N_CTS_44_1KHZ] = { + /* N and CTS values for 44.1 kHz, 88.2 kHz and 176.4 kHz rates*/ + { 25174825, { 7007, 31250, 0 } }, /* 25.20/1.001 MHz */ + { 25200000, { 6272, 28000, 0 } }, /* 25.20 MHz */ + { 27000000, { 6272, 30000, 0 } }, /* 27.00 MHz */ + { 27027000, { 6272, 30030, 0 } }, /* 27.00*1.001 MHz */ + { 54000000, { 6272, 60000, 0 } }, /* 54.00 MHz */ + { 54054000, { 6272, 60060, 0 } }, /* 54.00*1.001 MHz */ + { 74175824, { 17836, 234375, 0 } }, /* 74.25/1.001 MHz */ + { 74250000, { 6272, 82500, 0 } }, /* 74.25 MHz */ + { 148351648, { 8918, 234375, 0 } }, /* 148.50/1.001 MHz */ + { 148500000, { 6272, 165000, 0 } }, /* 148.50 MHz */ + { 296703296, { 4459, 234375, 0 } }, /* 297/1.001 MHz (truncated) */ + { 296703297, { 4459, 234375, 0 } }, /* 297/1.001 MHz (rounded) */ + { 297000000, { 4704, 247500, 0 } }, /* 297 MHz */ + }, + [HDMI_AUDIO_N_CTS_48KHZ] = { + /* N and CTS values for 48 kHz, 96 kHz and 192 kHz rates*/ + { 25174825, { 6864, 28125, 0 } }, /* 25.20/1.001 MHz */ + { 25200000, { 6144, 25200, 0 } }, /* 25.20 MHz */ + { 27000000, { 6144, 27000, 0 } }, /* 27.00 MHz */ + { 27027000, { 6144, 27027, 0 } }, /* 27.00*1.001 MHz */ + { 54000000, { 6144, 54000, 0 } }, /* 54.00 MHz */ + { 54054000, { 6144, 54054, 0 } }, /* 54.00*1.001 MHz */ + { 74175824, { 11648, 140625, 0 } }, /* 74.25/1.001 MHz */ + { 74250000, { 6144, 74250, 0 } }, /* 74.25 MHz */ + { 148351648, { 5824, 140625, 0 } }, /* 148.50/1.001 MHz */ + { 148500000, { 6144, 148500, 0 } }, /* 148.50 MHz */ + { 296703296, { 5824, 281250, 0 } }, /* 297/1.001 MHz (truncated) */ + { 296703297, { 5824, 281250, 0 } }, /* 297/1.001 MHz (rounded) */ + { 297000000, { 5120, 247500, 0 } }, /* 297 MHz */ + } +}; + +/** + * hdmi_audio_get_coherent_n_cts() - compute N and CTS parameters for coherent + * clocks. Coherent clock means that audio and TMDS clocks have the same + * source (no drifts between clocks). + * + * @audio_fs: audio frame clock frequency in Hz + * @tmds_clk: HDMI TMDS clock frequency in Hz + * @n_cts: N and CTS parameter returned to user + * + * Values computed are based on table described in HDMI specification 1.4b + * + * Returns 0 on success or a negative error code on failure. + */ +int hdmi_audio_get_coherent_n_cts(unsigned int audio_fs, + unsigned int tmds_clk, + struct hdmi_audio_n_cts *n_cts) +{ + int audio_freq_id, i; + int rate_coeff = 1; + u64 val, min; + const struct hdmi_audio_acr *acr_table; + const struct hdmi_audio_n_cts *predef_n_cts = NULL; + + switch (audio_fs) { + case 32000: + audio_freq_id = HDMI_AUDIO_N_CTS_32KHZ; + n_cts->n = 4096; + break; + case 44100: + audio_freq_id = HDMI_AUDIO_N_CTS_44_1KHZ; + n_cts->n = 6272; + break; + case 48000: + audio_freq_id = HDMI_AUDIO_N_CTS_48KHZ; + n_cts->n = 6144; + break; + case 88200: + audio_freq_id = HDMI_AUDIO_N_CTS_44_1KHZ; + rate_coeff = 2; + n_cts->n = 6272 * 2; + break; + case 96000: + audio_freq_id = HDMI_AUDIO_N_CTS_48KHZ; + rate_coeff = 2; + n_cts->n = 6144 * 2; + break; + case 176400: + audio_freq_id = HDMI_AUDIO_N_CTS_44_1KHZ; + rate_coeff = 4; + n_cts->n = 6272 * 4; + break; + case 192000: + audio_freq_id = HDMI_AUDIO_N_CTS_48KHZ; + rate_coeff = 4; + n_cts->n = 6144 * 4; + break; + default: + return -EINVAL; + } + + acr_table = hdmi_audio_standard_acr[audio_freq_id]; + for (i = 0; i < ARRAY_SIZE(hdmi_audio_standard_acr[0]); i++) { + if (tmds_clk == acr_table[i].tmds_clk) { + predef_n_cts = &acr_table[i].n_cts; + n_cts->n = predef_n_cts->n * rate_coeff; + n_cts->cts = predef_n_cts->cts; + n_cts->cts_1_ratio = predef_n_cts->cts_1_ratio; + return 0; + } + } + + /* + * Pre-defined frequency not found. Compute CTS using formula: + * CTS = (Ftdms_clk * N) / (128 * audio_fs) + */ + val = (u64)tmds_clk * n_cts->n; + n_cts->cts = div64_u64(val, 128UL * audio_fs); + + n_cts->cts_1_ratio = 0; + min = (u64)n_cts->cts * 128UL * audio_fs; + if (min < val) { + /* + * Non-accurate value for CTS + * compute ratio, needed by user to alternate in ACR + * between CTS and CTS + 1 value. + */ + n_cts->cts_1_ratio = ((u32)(val - min)) * 100 / + (128 * audio_fs); + } + + return 0; +} +EXPORT_SYMBOL(hdmi_audio_get_coherent_n_cts); + +/** + * hdmi_audio_get_non_coherent_n() - get N parameter for non-coherent + * clocks. None-coherent clocks means that audio and TMDS clocks have not the + * same source (drifts between clocks). In this case assumption is that CTS is + * automatically calculated by hardware. + * + * @audio_fs: audio frame clock frequency in Hz + * + * Values computed are based on table described in HDMI specification 1.4b + * + * Returns n value. + */ +int hdmi_audio_get_non_coherent_n(unsigned int audio_fs) +{ + unsigned int n; + + switch (audio_fs) { + case 32000: + n = 4096; + break; + case 44100: + n = 6272; + break; + case 48000: + n = 6144; + break; + case 88200: + n = 6272 * 2; + break; + case 96000: + n = 6144 * 2; + break; + case 176400: + n = 6272 * 4; + break; + case 192000: + n = 6144 * 4; + break; + default: + /* Not pre-defined, recommended value: 128 * fs / 1000 */ + n = (audio_fs * 128) / 1000; + } + + return n; +} +EXPORT_SYMBOL(hdmi_audio_get_non_coherent_n); + diff --git a/include/linux/hdmi.h b/include/linux/hdmi.h index e974420..088d09f8 100644 --- a/include/linux/hdmi.h +++ b/include/linux/hdmi.h @@ -333,4 +333,28 @@ int hdmi_infoframe_unpack(union hdmi_infoframe *frame, void *buffer); void hdmi_infoframe_log(const char *level, struct device *dev, union hdmi_infoframe *frame);
+/** + * struct hdmi_audio_n_cts - n and cts parameter for ACR packets + * @n: N parameter + * @cts: CTS parameter + * @cts_1_ratio: ratio from 0 to 99 to alternate "CTS" and "CTS + 1" values + * ratio = 0: CTS parameter is accurate, no need to alternate with "CTS + 1" + * value + * ratio = x: Need to alternate with ACR "CTS + 1" value x percent of the time + * to generate accurate audio clock + * as exemple: if cts_1_ratio = 30: to have an accurate value, user + * should transfer CTS value 70% of the time and (CTS+1) value 30% of the time + */ +struct hdmi_audio_n_cts { + unsigned int n; + unsigned int cts; + unsigned int cts_1_ratio; +}; + +int hdmi_audio_get_coherent_n_cts(unsigned int audio_fs, + unsigned int tmds_clk, + struct hdmi_audio_n_cts *n_cts); + +int hdmi_audio_get_non_coherent_n(unsigned int audio_fs); + #endif /* _DRM_HDMI_H */