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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 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 | printk(KERN_WARNING "Calculated ACR N value is too small. You may experience audio problems.\n"); | |
78 | if (n > (128*freq/300)) | |
79 | printk(KERN_WARNING "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 | } |