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 a 7 * copy of this software and associated documentation files (the "Software"), 8 * to deal in the Software without restriction, including without limitation 9 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 10 * and/or sell copies of the Software, and to permit persons to whom the 11 * Software is furnished to do so, subject to the following conditions: 12 * 13 * The above copyright notice and this permission notice shall be included in 14 * all copies or substantial portions of the Software. 15 * 16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 19 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR 20 * 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 OR 22 * OTHER DEALINGS IN THE SOFTWARE. 23 * 24 * Authors: Christian König 25 */ 26 #include <linux/hdmi.h> 27 #include <linux/gcd.h> 28 #include <drm/drmP.h> 29 #include <drm/amdgpu_drm.h> 30 #include "amdgpu.h" 31 32 static 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 table 50 */ 51 static 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 larger 68 * 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 88 struct 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); 103 104 return res; 105 } 106