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 | |
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(a: n, b: 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, CTS: &res.cts_32khz, N: &res.n_32khz, freq: 32000); |
101 | amdgpu_afmt_calc_cts(clock, CTS: &res.cts_44_1khz, N: &res.n_44_1khz, freq: 44100); |
102 | amdgpu_afmt_calc_cts(clock, CTS: &res.cts_48khz, N: &res.n_48khz, freq: 48000); |
103 | |
104 | return res; |
105 | } |
106 | |