amdgpu_afmt.c revision 1.1 
1/*	$NetBSD: amdgpu_afmt.c,v 1.1 2018/08/27 01:34:43 riastradh Exp $	*/
2
3/*
4 * Copyright 2008 Advanced Micro Devices, Inc.
5 * Copyright 2008 Red Hat Inc.
6 * Copyright 2009 Christian König.
7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a
9 * copy of this software and associated documentation files (the "Software"),
10 * to deal in the Software without restriction, including without limitation
11 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
12 * and/or sell copies of the Software, and to permit persons to whom the
13 * Software is furnished to do so, subject to the following conditions:
14 *
15 * The above copyright notice and this permission notice shall be included in
16 * all copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
21 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
22 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
23 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
24 * OTHER DEALINGS IN THE SOFTWARE.
25 *
26 * Authors: Christian König
27 */
28#include <sys/cdefs.h>
29__KERNEL_RCSID(0, "$NetBSD: amdgpu_afmt.c,v 1.1 2018/08/27 01:34:43 riastradh Exp $");
30
31#include <linux/hdmi.h>
32#include <linux/gcd.h>
33#include <drm/drmP.h>
34#include <drm/amdgpu_drm.h>
35#include "amdgpu.h"
36
37static const struct amdgpu_afmt_acr amdgpu_afmt_predefined_acr[] = {
38    /*	     32kHz	  44.1kHz	48kHz    */
39    /* Clock      N     CTS      N     CTS      N     CTS */
40    {  25175,  4096,  25175, 28224, 125875,  6144,  25175 }, /*  25,20/1.001 MHz */
41    {  25200,  4096,  25200,  6272,  28000,  6144,  25200 }, /*  25.20       MHz */
42    {  27000,  4096,  27000,  6272,  30000,  6144,  27000 }, /*  27.00       MHz */
43    {  27027,  4096,  27027,  6272,  30030,  6144,  27027 }, /*  27.00*1.001 MHz */
44    {  54000,  4096,  54000,  6272,  60000,  6144,  54000 }, /*  54.00       MHz */
45    {  54054,  4096,  54054,  6272,  60060,  6144,  54054 }, /*  54.00*1.001 MHz */
46    {  74176,  4096,  74176,  5733,  75335,  6144,  74176 }, /*  74.25/1.001 MHz */
47    {  74250,  4096,  74250,  6272,  82500,  6144,  74250 }, /*  74.25       MHz */
48    { 148352,  4096, 148352,  5733, 150670,  6144, 148352 }, /* 148.50/1.001 MHz */
49    { 148500,  4096, 148500,  6272, 165000,  6144, 148500 }, /* 148.50       MHz */
50};
51
52
53/*
54 * calculate CTS and N values if they are not found in the table
55 */
56static void amdgpu_afmt_calc_cts(uint32_t clock, int *CTS, int *N, int freq)
57{
58	int n, cts;
59	unsigned long div, mul;
60
61	/* Safe, but overly large values */
62	n = 128 * freq;
63	cts = clock * 1000;
64
65	/* Smallest valid fraction */
66	div = gcd(n, cts);
67
68	n /= div;
69	cts /= div;
70
71	/*
72	 * The optimal N is 128*freq/1000. Calculate the closest larger
73	 * value that doesn't truncate any bits.
74	 */
75	mul = ((128*freq/1000) + (n-1))/n;
76
77	n *= mul;
78	cts *= mul;
79
80	/* Check that we are in spec (not always possible) */
81	if (n < (128*freq/1500))
82		printk(KERN_WARNING "Calculated ACR N value is too small. You may experience audio problems.\n");
83	if (n > (128*freq/300))
84		printk(KERN_WARNING "Calculated ACR N value is too large. You may experience audio problems.\n");
85
86	*N = n;
87	*CTS = cts;
88
89	DRM_DEBUG("Calculated ACR timing N=%d CTS=%d for frequency %d\n",
90		  *N, *CTS, freq);
91}
92
93struct amdgpu_afmt_acr amdgpu_afmt_acr(uint32_t clock)
94{
95	struct amdgpu_afmt_acr res;
96	u8 i;
97
98	/* Precalculated values for common clocks */
99	for (i = 0; i < ARRAY_SIZE(amdgpu_afmt_predefined_acr); i++) {
100		if (amdgpu_afmt_predefined_acr[i].clock == clock)
101			return amdgpu_afmt_predefined_acr[i];
102	}
103
104	/* And odd clocks get manually calculated */
105	amdgpu_afmt_calc_cts(clock, &res.cts_32khz, &res.n_32khz, 32000);
106	amdgpu_afmt_calc_cts(clock, &res.cts_44_1khz, &res.n_44_1khz, 44100);
107	amdgpu_afmt_calc_cts(clock, &res.cts_48khz, &res.n_48khz, 48000);
108
109	return res;
110}
111