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1/*2 * Copyright 2008 Advanced Micro Devices, Inc.3 * Copyright 2008 Red Hat Inc.4 * Copyright 2009 Christian König.5 *6 * Permission is hereby granted, free of charge, to any person obtaining a7 * copy of this software and associated documentation files (the "Software"),8 * to deal in the Software without restriction, including without limitation9 * the rights to use, copy, modify, merge, publish, distribute, sublicense,10 * and/or sell copies of the Software, and to permit persons to whom the11 * Software is furnished to do so, subject to the following conditions:12 *13 * The above copyright notice and this permission notice shall be included in14 * all copies or substantial portions of the Software.15 *16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL19 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR20 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,21 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR22 * OTHER DEALINGS IN THE SOFTWARE.23 *24 * Authors: Christian König25 */26#include <linux/hdmi.h>27#include <linux/gcd.h>28 29#include <drm/amdgpu_drm.h>30#include "amdgpu.h"31 32static const struct amdgpu_afmt_acr amdgpu_afmt_predefined_acr[] = {33 /* 32kHz 44.1kHz 48kHz */34 /* Clock N CTS N CTS N CTS */35 { 25175, 4096, 25175, 28224, 125875, 6144, 25175 }, /* 25,20/1.001 MHz */36 { 25200, 4096, 25200, 6272, 28000, 6144, 25200 }, /* 25.20 MHz */37 { 27000, 4096, 27000, 6272, 30000, 6144, 27000 }, /* 27.00 MHz */38 { 27027, 4096, 27027, 6272, 30030, 6144, 27027 }, /* 27.00*1.001 MHz */39 { 54000, 4096, 54000, 6272, 60000, 6144, 54000 }, /* 54.00 MHz */40 { 54054, 4096, 54054, 6272, 60060, 6144, 54054 }, /* 54.00*1.001 MHz */41 { 74176, 4096, 74176, 5733, 75335, 6144, 74176 }, /* 74.25/1.001 MHz */42 { 74250, 4096, 74250, 6272, 82500, 6144, 74250 }, /* 74.25 MHz */43 { 148352, 4096, 148352, 5733, 150670, 6144, 148352 }, /* 148.50/1.001 MHz */44 { 148500, 4096, 148500, 6272, 165000, 6144, 148500 }, /* 148.50 MHz */45};46 47 48/*49 * calculate CTS and N values if they are not found in the table50 */51static void amdgpu_afmt_calc_cts(uint32_t clock, int *CTS, int *N, int freq)52{53 int n, cts;54 unsigned long div, mul;55 56 /* Safe, but overly large values */57 n = 128 * freq;58 cts = clock * 1000;59 60 /* Smallest valid fraction */61 div = gcd(n, cts);62 63 n /= div;64 cts /= div;65 66 /*67 * The optimal N is 128*freq/1000. Calculate the closest larger68 * value that doesn't truncate any bits.69 */70 mul = ((128*freq/1000) + (n-1))/n;71 72 n *= mul;73 cts *= mul;74 75 /* Check that we are in spec (not always possible) */76 if (n < (128*freq/1500))77 pr_warn("Calculated ACR N value is too small. You may experience audio problems.\n");78 if (n > (128*freq/300))79 pr_warn("Calculated ACR N value is too large. You may experience audio problems.\n");80 81 *N = n;82 *CTS = cts;83 84 DRM_DEBUG("Calculated ACR timing N=%d CTS=%d for frequency %d\n",85 *N, *CTS, freq);86}87 88struct amdgpu_afmt_acr amdgpu_afmt_acr(uint32_t clock)89{90 struct amdgpu_afmt_acr res;91 u8 i;92 93 /* Precalculated values for common clocks */94 for (i = 0; i < ARRAY_SIZE(amdgpu_afmt_predefined_acr); i++) {95 if (amdgpu_afmt_predefined_acr[i].clock == clock)96 return amdgpu_afmt_predefined_acr[i];97 }98 99 /* And odd clocks get manually calculated */100 amdgpu_afmt_calc_cts(clock, &res.cts_32khz, &res.n_32khz, 32000);101 amdgpu_afmt_calc_cts(clock, &res.cts_44_1khz, &res.n_44_1khz, 44100);102 amdgpu_afmt_calc_cts(clock, &res.cts_48khz, &res.n_48khz, 48000);103 res.clock = clock;104 105 return res;106}107