projects/linux·blob master · refs

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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
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 table
50 */
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 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
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}