Add helper function to compute HDMI CTS and N parameters Implementation is based on HDMI 1.4b specification.
Signed-off-by: Arnaud Pouliquen arnaud.pouliquen@st.com Cc: linux-fbdev@vger.kernel.org Cc: Jean-Christophe Plagniol-Villard plagnioj@jcrosoft.com Cc: Tomi Valkeinen tomi.valkeinen@ti.com --- drivers/video/hdmi.c | 147 +++++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/hdmi.h | 12 +++++ 2 files changed, 159 insertions(+)
diff --git a/drivers/video/hdmi.c b/drivers/video/hdmi.c index 1626892..93e2fdf 100644 --- a/drivers/video/hdmi.c +++ b/drivers/video/hdmi.c @@ -1242,3 +1242,150 @@ 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 audio_rate { + HDMI_AUDIO_N_CTS_32KHZ, + HDMI_AUDIO_N_CTS_44_1KHZ, + HDMI_AUDIO_N_CTS_48KHZ, +}; + +struct hdmi_audio_acr { + unsigned long pixel_clk; + struct hdmi_audio_n_cts n_cts; +}; + +static const struct hdmi_audio_acr hdmi_audio_standard_acr[3][12] = { + { /*32 kHz*/ + { 25175, { 4576, 28125 } }, /* 25,20/1.001 MHz */ + { 25200, { 4096, 25200 } }, /* 25.20 MHz */ + { 27000, { 4096, 27000 } }, /* 27.00 MHz */ + { 27027, { 4096, 27027 } }, /* 27.00*1.001 MHz */ + { 54000, { 4096, 54000 } }, /* 54.00 MHz */ + { 54054, { 4096, 54054 } }, /* 54.00*1.001 MHz */ + { 74176, { 11648, 310938 } }, /* 74.25/1.001 MHz */ + { 74250, { 4096, 74250 } }, /* 74.25 MHz */ + { 148352, { 11648, 421875 } }, /* 148.50/1.001 MHz */ + { 148500, { 4096, 148500 } }, /* 148.50 MHz */ + { 296703, { 5824, 421875 } }, /* 297/1.001 MHz */ + { 297000, { 3072, 222750 } }, /* 297 MHz */ + }, + { /*44.1 kHz, 88.2 kHz 176.4 kHz*/ + { 25175, { 7007, 31250 } }, /* 25,20/1.001 MHz */ + { 25200, { 6272, 28000 } }, /* 25.20 MHz */ + { 27000, { 6272, 30000 } }, /* 27.00 MHz */ + { 27027, { 6272, 30030 } }, /* 27.00*1.001 MHz */ + { 54000, { 6272, 60000 } }, /* 54.00 MHz */ + { 54054, { 6272, 60060 } }, /* 54.00*1.001 MHz */ + { 74176, { 17836, 234375 } }, /* 74.25/1.001 MHz */ + { 74250, { 6272, 82500 } }, /* 74.25 MHz */ + { 148352, { 8918, 234375 } }, /* 148.50/1.001 MHz */ + { 148500, { 6272, 165000 } }, /* 148.50 MHz */ + { 296703, { 4459, 234375 } }, /* 297/1.001 MHz */ + { 297000, { 4704, 247500 } }, /* 297 MHz */ + }, + { /*48 kHz, 96 kHz 192 kHz*/ + { 25175, { 6864, 28125 } }, /* 25,20/1.001 MHz */ + { 25200, { 6144, 25200 } }, /* 25.20 MHz */ + { 27000, { 6144, 27000 } }, /* 27.00 MHz */ + { 27027, { 6144, 27027 } }, /* 27.00*1.001 MHz */ + { 54000, { 6144, 54000 } }, /* 54.00 MHz */ + { 54054, { 6144, 54054 } }, /* 54.00*1.001 MHz */ + { 74176, { 11648, 140625 } }, /* 74.25/1.001 MHz */ + { 74250, { 6144, 74250 } }, /* 74.25 MHz */ + { 148352, { 5824, 140625 } }, /* 148.50/1.001 MHz */ + { 148500, { 6144, 148500 } }, /* 148.50 MHz */ + { 296703, { 5824, 281250 } }, /* 297/1.001 MHz */ + { 297000, { 5120, 247500 } }, /* 297 MHz */ + } +}; + +/** + * hdmi_compute_n_cts() - compute N and CTS parameters + * @audio_fs: audio frame clock frequency in KHz + * @pixel_clk: pixel cloack frequency in kHz + * @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_compute_n_cts(enum hdmi_audio_sample_frequency audio_fs, + unsigned long pixel_clk, + struct hdmi_audio_n_cts *n_cts) +{ + int audio_freq_id, i; + int ratio = 1; + const struct hdmi_audio_acr *acr_table; + const struct hdmi_audio_n_cts *predef_n_cts = NULL; + + switch (audio_fs) { + case HDMI_AUDIO_SAMPLE_FREQUENCY_32000: + audio_freq_id = HDMI_AUDIO_N_CTS_32KHZ; + n_cts->n = 4096; + break; + + case HDMI_AUDIO_SAMPLE_FREQUENCY_44100: + audio_freq_id = HDMI_AUDIO_N_CTS_44_1KHZ; + n_cts->n = 6272; + break; + + case HDMI_AUDIO_SAMPLE_FREQUENCY_48000: + audio_freq_id = HDMI_AUDIO_N_CTS_48KHZ; + n_cts->n = 6144; + break; + + case HDMI_AUDIO_SAMPLE_FREQUENCY_88200: + audio_freq_id = HDMI_AUDIO_N_CTS_44_1KHZ; + ratio = 2; + n_cts->n = 6272 * 2; + break; + + case HDMI_AUDIO_SAMPLE_FREQUENCY_96000: + audio_freq_id = HDMI_AUDIO_N_CTS_48KHZ; + ratio = 2; + n_cts->n = 6144 * 2; + break; + + case HDMI_AUDIO_SAMPLE_FREQUENCY_176400: + audio_freq_id = HDMI_AUDIO_N_CTS_44_1KHZ; + ratio = 2; + n_cts->n = 6272 * 4; + break; + + case HDMI_AUDIO_SAMPLE_FREQUENCY_192000: + audio_freq_id = HDMI_AUDIO_N_CTS_48KHZ; + ratio = 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 (pixel_clk == acr_table[i].pixel_clk) { + predef_n_cts = &acr_table[i].n_cts; + break; + } + } + + if (!predef_n_cts) { + /* + * predefined frequency not found. Compute CTS using formula: + * CTS = (Ftdms_clk * N) / (128* audio_fs) + */ + n_cts->cts = pixel_clk * n_cts->n / (128 * audio_fs); + } else { + n_cts->n = predef_n_cts->n * ratio; + n_cts->cts = predef_n_cts->cts; + } + + return 0; +} +EXPORT_SYMBOL(hdmi_audio_compute_n_cts); + diff --git a/include/linux/hdmi.h b/include/linux/hdmi.h index e974420..95c2b12 100644 --- a/include/linux/hdmi.h +++ b/include/linux/hdmi.h @@ -333,4 +333,16 @@ 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 + */ +struct hdmi_audio_n_cts { + unsigned int n; + unsigned int cts; +}; + +int hdmi_audio_compute_n_cts(enum hdmi_audio_sample_frequency audio_fs, + unsigned long pixel_clk, + struct hdmi_audio_n_cts *n_cts); + #endif /* _DRM_HDMI_H */