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 <ykk@rock-chips.com> Reviewed-on: https://chromium-review.googlesource.com/315424 Reviewed-by: Douglas Anderson <dianders@chromium.org>
This commit is contained in:
Yakir Yang
Huang, Tao
@@ -53,6 +53,62 @@ enum hdmi_datamap {
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YCbCr422_12B = 0x12,
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};
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/*
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* Unless otherwise noted, entries in this table are 100% optimization.
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* Values can be obtained from hdmi_compute_n() but that function is
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* slow so we pre-compute values we expect to see.
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*
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* All 32k and 48k values are expected to be the same (due to the way
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* the math works) for any rate that's an exact kHz.
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*/
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static const struct dw_hdmi_audio_tmds_n common_tmds_n_table[] = {
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{ .tmds = 25175000, .n_32k = 4096, .n_44k1 = 12854, .n_48k = 6144, },
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{ .tmds = 25200000, .n_32k = 4096, .n_44k1 = 5656, .n_48k = 6144, },
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{ .tmds = 27000000, .n_32k = 4096, .n_44k1 = 5488, .n_48k = 6144, },
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{ .tmds = 28320000, .n_32k = 4096, .n_44k1 = 5586, .n_48k = 6144, },
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{ .tmds = 30240000, .n_32k = 4096, .n_44k1 = 5642, .n_48k = 6144, },
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{ .tmds = 31500000, .n_32k = 4096, .n_44k1 = 5600, .n_48k = 6144, },
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{ .tmds = 32000000, .n_32k = 4096, .n_44k1 = 5733, .n_48k = 6144, },
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{ .tmds = 33750000, .n_32k = 4096, .n_44k1 = 6272, .n_48k = 6144, },
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{ .tmds = 36000000, .n_32k = 4096, .n_44k1 = 5684, .n_48k = 6144, },
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{ .tmds = 40000000, .n_32k = 4096, .n_44k1 = 5733, .n_48k = 6144, },
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{ .tmds = 49500000, .n_32k = 4096, .n_44k1 = 5488, .n_48k = 6144, },
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{ .tmds = 50000000, .n_32k = 4096, .n_44k1 = 5292, .n_48k = 6144, },
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{ .tmds = 54000000, .n_32k = 4096, .n_44k1 = 5684, .n_48k = 6144, },
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{ .tmds = 65000000, .n_32k = 4096, .n_44k1 = 7056, .n_48k = 6144, },
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{ .tmds = 68250000, .n_32k = 4096, .n_44k1 = 5376, .n_48k = 6144, },
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{ .tmds = 71000000, .n_32k = 4096, .n_44k1 = 7056, .n_48k = 6144, },
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{ .tmds = 72000000, .n_32k = 4096, .n_44k1 = 5635, .n_48k = 6144, },
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{ .tmds = 73250000, .n_32k = 4096, .n_44k1 = 14112, .n_48k = 6144, },
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{ .tmds = 74250000, .n_32k = 4096, .n_44k1 = 6272, .n_48k = 6144, },
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{ .tmds = 75000000, .n_32k = 4096, .n_44k1 = 5880, .n_48k = 6144, },
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{ .tmds = 78750000, .n_32k = 4096, .n_44k1 = 5600, .n_48k = 6144, },
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{ .tmds = 78800000, .n_32k = 4096, .n_44k1 = 5292, .n_48k = 6144, },
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{ .tmds = 79500000, .n_32k = 4096, .n_44k1 = 4704, .n_48k = 6144, },
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{ .tmds = 83500000, .n_32k = 4096, .n_44k1 = 7056, .n_48k = 6144, },
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{ .tmds = 85500000, .n_32k = 4096, .n_44k1 = 5488, .n_48k = 6144, },
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{ .tmds = 88750000, .n_32k = 4096, .n_44k1 = 14112, .n_48k = 6144, },
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{ .tmds = 97750000, .n_32k = 4096, .n_44k1 = 14112, .n_48k = 6144, },
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{ .tmds = 101000000, .n_32k = 4096, .n_44k1 = 7056, .n_48k = 6144, },
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{ .tmds = 106500000, .n_32k = 4096, .n_44k1 = 4704, .n_48k = 6144, },
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{ .tmds = 108000000, .n_32k = 4096, .n_44k1 = 5684, .n_48k = 6144, },
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{ .tmds = 115500000, .n_32k = 4096, .n_44k1 = 5712, .n_48k = 6144, },
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{ .tmds = 119000000, .n_32k = 4096, .n_44k1 = 5544, .n_48k = 6144, },
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{ .tmds = 135000000, .n_32k = 4096, .n_44k1 = 5488, .n_48k = 6144, },
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{ .tmds = 146250000, .n_32k = 4096, .n_44k1 = 6272, .n_48k = 6144, },
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{ .tmds = 148500000, .n_32k = 4096, .n_44k1 = 5488, .n_48k = 6144, },
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{ .tmds = 154000000, .n_32k = 4096, .n_44k1 = 5544, .n_48k = 6144, },
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{ .tmds = 162000000, .n_32k = 4096, .n_44k1 = 5684, .n_48k = 6144, },
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/* For 297 MHz+ HDMI spec have some other rule for setting N */
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{ .tmds = 297000000, .n_32k = 3073, .n_44k1 = 4704, .n_48k = 5120, },
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{ .tmds = 594000000, .n_32k = 3073, .n_44k1 = 9408, .n_48k = 10240, },
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/* End of table */
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{ .tmds = 0, .n_32k = 0, .n_44k1 = 0, .n_48k = 0, },
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};
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static const u16 csc_coeff_default[3][4] = {
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{ 0x2000, 0x0000, 0x0000, 0x0000 },
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{ 0x0000, 0x2000, 0x0000, 0x0000 },
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@@ -217,60 +273,117 @@ static void hdmi_set_cts_n(struct dw_hdmi *hdmi, unsigned int cts,
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hdmi_writeb(hdmi, n & 0xff, HDMI_AUD_N1);
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}
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static unsigned int hdmi_compute_n(unsigned int freq, unsigned long pixel_clk)
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static int hdmi_match_tmds_n_table(struct dw_hdmi *hdmi,
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unsigned long pixel_clk,
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unsigned long freq)
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{
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unsigned int n = (128 * freq) / 1000;
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unsigned int mult = 1;
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const struct dw_hdmi_plat_data *plat_data = hdmi->plat_data;
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const struct dw_hdmi_audio_tmds_n *tmds_n = NULL;
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int i;
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while (freq > 48000) {
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mult *= 2;
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freq /= 2;
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if (plat_data->tmds_n_table) {
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for (i = 0; plat_data->tmds_n_table[i].tmds != 0; i++) {
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if (pixel_clk == plat_data->tmds_n_table[i].tmds) {
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tmds_n = &plat_data->tmds_n_table[i];
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break;
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}
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}
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}
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if (tmds_n == NULL) {
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for (i = 0; common_tmds_n_table[i].tmds != 0; i++) {
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if (pixel_clk == common_tmds_n_table[i].tmds) {
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tmds_n = &common_tmds_n_table[i];
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break;
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}
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}
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}
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if (tmds_n == NULL)
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return -ENOENT;
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switch (freq) {
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case 32000:
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if (pixel_clk == 25175000)
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n = 4576;
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else if (pixel_clk == 27027000)
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n = 4096;
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else if (pixel_clk == 74176000 || pixel_clk == 148352000)
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n = 11648;
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else
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n = 4096;
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n *= mult;
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break;
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return tmds_n->n_32k;
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case 44100:
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if (pixel_clk == 25175000)
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n = 7007;
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else if (pixel_clk == 74176000)
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n = 17836;
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else if (pixel_clk == 148352000)
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n = 8918;
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else
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n = 6272;
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n *= mult;
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break;
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case 88200:
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case 176400:
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return (freq / 44100) * tmds_n->n_44k1;
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case 48000:
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if (pixel_clk == 25175000)
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n = 6864;
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else if (pixel_clk == 27027000)
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n = 6144;
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else if (pixel_clk == 74176000)
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n = 11648;
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else if (pixel_clk == 148352000)
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n = 5824;
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else
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n = 6144;
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n *= mult;
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break;
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case 96000:
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case 192000:
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return (freq / 48000) * tmds_n->n_48k;
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default:
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break;
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return -ENOENT;
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}
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}
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static u64 hdmi_audio_math_diff(unsigned int freq, unsigned int n,
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unsigned int pixel_clk)
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{
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u64 final, diff;
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u64 cts;
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final = (u64)pixel_clk * n;
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cts = final;
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do_div(cts, 128 * freq);
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diff = final - (u64)cts * (128 * freq);
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return diff;
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}
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static unsigned int hdmi_compute_n(struct dw_hdmi *hdmi,
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unsigned long pixel_clk,
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unsigned long freq)
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{
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unsigned int min_n = DIV_ROUND_UP((128 * freq), 1500);
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unsigned int max_n = (128 * freq) / 300;
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unsigned int ideal_n = (128 * freq) / 1000;
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unsigned int best_n_distance = ideal_n;
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unsigned int best_n = 0;
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u64 best_diff = U64_MAX;
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int n;
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/* If the ideal N could satisfy the audio math, then just take it */
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if (hdmi_audio_math_diff(freq, ideal_n, pixel_clk) == 0)
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return ideal_n;
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for (n = min_n; n <= max_n; n++) {
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u64 diff = hdmi_audio_math_diff(freq, n, pixel_clk);
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if (diff < best_diff || (diff == best_diff &&
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abs(n - ideal_n) < best_n_distance)) {
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best_n = n;
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best_diff = diff;
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best_n_distance = abs(best_n - ideal_n);
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}
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/*
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* The best N already satisfy the audio math, and also be
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* the closest value to ideal N, so just cut the loop.
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*/
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if ((best_diff == 0) && (abs(n - ideal_n) > best_n_distance))
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break;
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}
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return n;
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return best_n;
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}
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static unsigned int hdmi_find_n(struct dw_hdmi *hdmi, unsigned long pixel_clk,
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unsigned long sample_rate)
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{
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int n;
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n = hdmi_match_tmds_n_table(hdmi, pixel_clk, sample_rate);
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if (n > 0)
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return n;
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dev_warn(hdmi->dev, "Rate %lu missing; compute N dynamically\n",
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pixel_clk);
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return hdmi_compute_n(hdmi, pixel_clk, sample_rate);
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}
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static void hdmi_set_clk_regenerator(struct dw_hdmi *hdmi,
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@@ -280,7 +393,7 @@ static void hdmi_set_clk_regenerator(struct dw_hdmi *hdmi,
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unsigned int n, cts;
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u64 tmp;
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n = hdmi_compute_n(sample_rate, pixel_clk);
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n = hdmi_find_n(hdmi, pixel_clk, sample_rate);
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/*
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* Compute the CTS value from the N value. Note that CTS and N
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@@ -28,6 +28,13 @@ enum dw_hdmi_devtype {
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RK3399_HDMI,
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};
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struct dw_hdmi_audio_tmds_n {
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unsigned long tmds;
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unsigned int n_32k;
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unsigned int n_44k1;
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unsigned int n_48k;
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};
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struct dw_hdmi_mpll_config {
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unsigned long mpixelclock;
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struct {
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@@ -50,6 +57,7 @@ struct dw_hdmi_phy_config {
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struct dw_hdmi_plat_data {
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enum dw_hdmi_devtype dev_type;
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const struct dw_hdmi_audio_tmds_n *tmds_n_table;
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const struct dw_hdmi_mpll_config *mpll_cfg;
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const struct dw_hdmi_curr_ctrl *cur_ctr;
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const struct dw_hdmi_phy_config *phy_config;
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