From: Yakir Yang Date: Wed, 2 Dec 2015 09:50:56 +0000 (+0800) Subject: CHROMIUM: drm: bridge/dw_hdmi: improved the hdmi audio N/CTS cacluate math X-Git-Tag: firefly_0821_release~2129 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=d46288cf0b5fa5313bf373d0fa4cee6a05310fc4;p=firefly-linux-kernel-4.4.55.git CHROMIUM: drm: bridge/dw_hdmi: improved the hdmi audio N/CTS cacluate math The original math would bring some inaccurate to N/CTS that would caused those magic number won't fit the HDMI 1.4 Spec request: 128 * SampleRate = Tmds * N / CTS; So this time we try to improved to math of N that would find the minimal inaccurate with the HDMI 1.4 Spec. Change-Id: Ied3cde3c352d955ae6f15d5e7fb172e92316c2a5 Signed-off-by: Yakir Yang Reviewed-on: https://chromium-review.googlesource.com/315424 Reviewed-by: Douglas Anderson --- diff --git a/drivers/gpu/drm/bridge/dw-hdmi.c b/drivers/gpu/drm/bridge/dw-hdmi.c index 641d94725970..c28eb33adf1c 100644 --- a/drivers/gpu/drm/bridge/dw-hdmi.c +++ b/drivers/gpu/drm/bridge/dw-hdmi.c @@ -53,6 +53,62 @@ enum hdmi_datamap { YCbCr422_12B = 0x12, }; +/* + * Unless otherwise noted, entries in this table are 100% optimization. + * Values can be obtained from hdmi_compute_n() but that function is + * slow so we pre-compute values we expect to see. + * + * All 32k and 48k values are expected to be the same (due to the way + * the math works) for any rate that's an exact kHz. + */ +static const struct dw_hdmi_audio_tmds_n common_tmds_n_table[] = { + { .tmds = 25175000, .n_32k = 4096, .n_44k1 = 12854, .n_48k = 6144, }, + { .tmds = 25200000, .n_32k = 4096, .n_44k1 = 5656, .n_48k = 6144, }, + { .tmds = 27000000, .n_32k = 4096, .n_44k1 = 5488, .n_48k = 6144, }, + { .tmds = 28320000, .n_32k = 4096, .n_44k1 = 5586, .n_48k = 6144, }, + { .tmds = 30240000, .n_32k = 4096, .n_44k1 = 5642, .n_48k = 6144, }, + { .tmds = 31500000, .n_32k = 4096, .n_44k1 = 5600, .n_48k = 6144, }, + { .tmds = 32000000, .n_32k = 4096, .n_44k1 = 5733, .n_48k = 6144, }, + { .tmds = 33750000, .n_32k = 4096, .n_44k1 = 6272, .n_48k = 6144, }, + { .tmds = 36000000, .n_32k = 4096, .n_44k1 = 5684, .n_48k = 6144, }, + { .tmds = 40000000, .n_32k = 4096, .n_44k1 = 5733, .n_48k = 6144, }, + { .tmds = 49500000, .n_32k = 4096, .n_44k1 = 5488, .n_48k = 6144, }, + { .tmds = 50000000, .n_32k = 4096, .n_44k1 = 5292, .n_48k = 6144, }, + { .tmds = 54000000, .n_32k = 4096, .n_44k1 = 5684, .n_48k = 6144, }, + { .tmds = 65000000, .n_32k = 4096, .n_44k1 = 7056, .n_48k = 6144, }, + { .tmds = 68250000, .n_32k = 4096, .n_44k1 = 5376, .n_48k = 6144, }, + { .tmds = 71000000, .n_32k = 4096, .n_44k1 = 7056, .n_48k = 6144, }, + { .tmds = 72000000, .n_32k = 4096, .n_44k1 = 5635, .n_48k = 6144, }, + { .tmds = 73250000, .n_32k = 4096, .n_44k1 = 14112, .n_48k = 6144, }, + { .tmds = 74250000, .n_32k = 4096, .n_44k1 = 6272, .n_48k = 6144, }, + { .tmds = 75000000, .n_32k = 4096, .n_44k1 = 5880, .n_48k = 6144, }, + { .tmds = 78750000, .n_32k = 4096, .n_44k1 = 5600, .n_48k = 6144, }, + { .tmds = 78800000, .n_32k = 4096, .n_44k1 = 5292, .n_48k = 6144, }, + { .tmds = 79500000, .n_32k = 4096, .n_44k1 = 4704, .n_48k = 6144, }, + { .tmds = 83500000, .n_32k = 4096, .n_44k1 = 7056, .n_48k = 6144, }, + { .tmds = 85500000, .n_32k = 4096, .n_44k1 = 5488, .n_48k = 6144, }, + { .tmds = 88750000, .n_32k = 4096, .n_44k1 = 14112, .n_48k = 6144, }, + { .tmds = 97750000, .n_32k = 4096, .n_44k1 = 14112, .n_48k = 6144, }, + { .tmds = 101000000, .n_32k = 4096, .n_44k1 = 7056, .n_48k = 6144, }, + { .tmds = 106500000, .n_32k = 4096, .n_44k1 = 4704, .n_48k = 6144, }, + { .tmds = 108000000, .n_32k = 4096, .n_44k1 = 5684, .n_48k = 6144, }, + { .tmds = 115500000, .n_32k = 4096, .n_44k1 = 5712, .n_48k = 6144, }, + { .tmds = 119000000, .n_32k = 4096, .n_44k1 = 5544, .n_48k = 6144, }, + { .tmds = 135000000, .n_32k = 4096, .n_44k1 = 5488, .n_48k = 6144, }, + { .tmds = 146250000, .n_32k = 4096, .n_44k1 = 6272, .n_48k = 6144, }, + { .tmds = 148500000, .n_32k = 4096, .n_44k1 = 5488, .n_48k = 6144, }, + { .tmds = 154000000, .n_32k = 4096, .n_44k1 = 5544, .n_48k = 6144, }, + { .tmds = 162000000, .n_32k = 4096, .n_44k1 = 5684, .n_48k = 6144, }, + + /* For 297 MHz+ HDMI spec have some other rule for setting N */ + { .tmds = 297000000, .n_32k = 3073, .n_44k1 = 4704, .n_48k = 5120, }, + { .tmds = 594000000, .n_32k = 3073, .n_44k1 = 9408, .n_48k = 10240, }, + + /* End of table */ + { .tmds = 0, .n_32k = 0, .n_44k1 = 0, .n_48k = 0, }, +}; + + static const u16 csc_coeff_default[3][4] = { { 0x2000, 0x0000, 0x0000, 0x0000 }, { 0x0000, 0x2000, 0x0000, 0x0000 }, @@ -217,60 +273,117 @@ static void hdmi_set_cts_n(struct dw_hdmi *hdmi, unsigned int cts, hdmi_writeb(hdmi, n & 0xff, HDMI_AUD_N1); } -static unsigned int hdmi_compute_n(unsigned int freq, unsigned long pixel_clk) +static int hdmi_match_tmds_n_table(struct dw_hdmi *hdmi, + unsigned long pixel_clk, + unsigned long freq) { - unsigned int n = (128 * freq) / 1000; - unsigned int mult = 1; + const struct dw_hdmi_plat_data *plat_data = hdmi->plat_data; + const struct dw_hdmi_audio_tmds_n *tmds_n = NULL; + int i; - while (freq > 48000) { - mult *= 2; - freq /= 2; + if (plat_data->tmds_n_table) { + for (i = 0; plat_data->tmds_n_table[i].tmds != 0; i++) { + if (pixel_clk == plat_data->tmds_n_table[i].tmds) { + tmds_n = &plat_data->tmds_n_table[i]; + break; + } + } } + if (tmds_n == NULL) { + for (i = 0; common_tmds_n_table[i].tmds != 0; i++) { + if (pixel_clk == common_tmds_n_table[i].tmds) { + tmds_n = &common_tmds_n_table[i]; + break; + } + } + } + + if (tmds_n == NULL) + return -ENOENT; + switch (freq) { case 32000: - if (pixel_clk == 25175000) - n = 4576; - else if (pixel_clk == 27027000) - n = 4096; - else if (pixel_clk == 74176000 || pixel_clk == 148352000) - n = 11648; - else - n = 4096; - n *= mult; - break; - + return tmds_n->n_32k; case 44100: - if (pixel_clk == 25175000) - n = 7007; - else if (pixel_clk == 74176000) - n = 17836; - else if (pixel_clk == 148352000) - n = 8918; - else - n = 6272; - n *= mult; - break; - + case 88200: + case 176400: + return (freq / 44100) * tmds_n->n_44k1; case 48000: - if (pixel_clk == 25175000) - n = 6864; - else if (pixel_clk == 27027000) - n = 6144; - else if (pixel_clk == 74176000) - n = 11648; - else if (pixel_clk == 148352000) - n = 5824; - else - n = 6144; - n *= mult; - break; - + case 96000: + case 192000: + return (freq / 48000) * tmds_n->n_48k; default: - break; + return -ENOENT; + } +} + +static u64 hdmi_audio_math_diff(unsigned int freq, unsigned int n, + unsigned int pixel_clk) +{ + u64 final, diff; + u64 cts; + + final = (u64)pixel_clk * n; + + cts = final; + do_div(cts, 128 * freq); + + diff = final - (u64)cts * (128 * freq); + + return diff; +} + +static unsigned int hdmi_compute_n(struct dw_hdmi *hdmi, + unsigned long pixel_clk, + unsigned long freq) +{ + unsigned int min_n = DIV_ROUND_UP((128 * freq), 1500); + unsigned int max_n = (128 * freq) / 300; + unsigned int ideal_n = (128 * freq) / 1000; + unsigned int best_n_distance = ideal_n; + unsigned int best_n = 0; + u64 best_diff = U64_MAX; + int n; + + /* If the ideal N could satisfy the audio math, then just take it */ + if (hdmi_audio_math_diff(freq, ideal_n, pixel_clk) == 0) + return ideal_n; + + for (n = min_n; n <= max_n; n++) { + u64 diff = hdmi_audio_math_diff(freq, n, pixel_clk); + + if (diff < best_diff || (diff == best_diff && + abs(n - ideal_n) < best_n_distance)) { + best_n = n; + best_diff = diff; + best_n_distance = abs(best_n - ideal_n); + } + + /* + * The best N already satisfy the audio math, and also be + * the closest value to ideal N, so just cut the loop. + */ + if ((best_diff == 0) && (abs(n - ideal_n) > best_n_distance)) + break; } - return n; + return best_n; +} + +static unsigned int hdmi_find_n(struct dw_hdmi *hdmi, unsigned long pixel_clk, + unsigned long sample_rate) +{ + int n; + + n = hdmi_match_tmds_n_table(hdmi, pixel_clk, sample_rate); + if (n > 0) + return n; + + dev_warn(hdmi->dev, "Rate %lu missing; compute N dynamically\n", + pixel_clk); + + return hdmi_compute_n(hdmi, pixel_clk, sample_rate); } static void hdmi_set_clk_regenerator(struct dw_hdmi *hdmi, @@ -280,7 +393,7 @@ static void hdmi_set_clk_regenerator(struct dw_hdmi *hdmi, unsigned int n, cts; u64 tmp; - n = hdmi_compute_n(sample_rate, pixel_clk); + n = hdmi_find_n(hdmi, pixel_clk, sample_rate); /* * Compute the CTS value from the N value. Note that CTS and N diff --git a/include/drm/bridge/dw_hdmi.h b/include/drm/bridge/dw_hdmi.h index 26c06d5be23d..2fb760eb9797 100644 --- a/include/drm/bridge/dw_hdmi.h +++ b/include/drm/bridge/dw_hdmi.h @@ -28,6 +28,13 @@ enum dw_hdmi_devtype { RK3399_HDMI, }; +struct dw_hdmi_audio_tmds_n { + unsigned long tmds; + unsigned int n_32k; + unsigned int n_44k1; + unsigned int n_48k; +}; + struct dw_hdmi_mpll_config { unsigned long mpixelclock; struct { @@ -50,6 +57,7 @@ struct dw_hdmi_phy_config { struct dw_hdmi_plat_data { enum dw_hdmi_devtype dev_type; + const struct dw_hdmi_audio_tmds_n *tmds_n_table; const struct dw_hdmi_mpll_config *mpll_cfg; const struct dw_hdmi_curr_ctrl *cur_ctr; const struct dw_hdmi_phy_config *phy_config;