1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 drm_edid_load.c: use a built-in EDID data set or load it via the firmware
4 interface
5
6 Copyright (C) 2012 Carsten Emde <C.Emde@osadl.org>
7
8*/
9
10#include <linux/firmware.h>
11#include <linux/module.h>
12#include <linux/platform_device.h>
13
14#include <drm/drm_connector.h>
15#include <drm/drm_drv.h>
16#include <drm/drm_edid.h>
17#include <drm/drm_print.h>
18
19#include "drm_crtc_internal.h"
20
21static char edid_firmware[PATH_MAX];
22module_param_string(edid_firmware, edid_firmware, sizeof(edid_firmware), 0644);
23MODULE_PARM_DESC(edid_firmware,
24 "Do not probe monitor, use specified EDID blob from /lib/firmware instead.");
25
26static const struct drm_edid *edid_load(struct drm_connector *connector, const char *name)
27{
28 const struct firmware *fw = NULL;
29 const struct drm_edid *drm_edid;
30 int err;
31
32 err = request_firmware(fw: &fw, name, device: connector->dev->dev);
33 if (err) {
34 drm_err(connector->dev,
35 "[CONNECTOR:%d:%s] Requesting EDID firmware \"%s\" failed (err=%d)\n",
36 connector->base.id, connector->name,
37 name, err);
38 return ERR_PTR(error: err);
39 }
40
41 drm_dbg_kms(connector->dev, "[CONNECTOR:%d:%s] Loaded external firmware EDID \"%s\"\n",
42 connector->base.id, connector->name, name);
43
44 drm_edid = drm_edid_alloc(edid: fw->data, size: fw->size);
45 if (!drm_edid_valid(drm_edid)) {
46 drm_err(connector->dev, "Invalid firmware EDID \"%s\"\n", name);
47 drm_edid_free(drm_edid);
48 drm_edid = ERR_PTR(error: -EINVAL);
49 }
50
51 release_firmware(fw);
52
53 return drm_edid;
54}
55
56const struct drm_edid *drm_edid_load_firmware(struct drm_connector *connector)
57{
58 char *edidname, *last, *colon, *fwstr, *edidstr, *fallback = NULL;
59 const struct drm_edid *drm_edid;
60
61 if (edid_firmware[0] == '\0')
62 return ERR_PTR(error: -ENOENT);
63
64 /*
65 * If there are multiple edid files specified and separated
66 * by commas, search through the list looking for one that
67 * matches the connector.
68 *
69 * If there's one or more that doesn't specify a connector, keep
70 * the last one found one as a fallback.
71 */
72 fwstr = kstrdup(s: edid_firmware, GFP_KERNEL);
73 if (!fwstr)
74 return ERR_PTR(error: -ENOMEM);
75 edidstr = fwstr;
76
77 while ((edidname = strsep(&edidstr, ","))) {
78 colon = strchr(edidname, ':');
79 if (colon != NULL) {
80 if (strncmp(connector->name, edidname, colon - edidname))
81 continue;
82 edidname = colon + 1;
83 break;
84 }
85
86 if (*edidname != '\0') /* corner case: multiple ',' */
87 fallback = edidname;
88 }
89
90 if (!edidname) {
91 if (!fallback) {
92 kfree(objp: fwstr);
93 return ERR_PTR(error: -ENOENT);
94 }
95 edidname = fallback;
96 }
97
98 last = edidname + strlen(edidname) - 1;
99 if (*last == '\n')
100 *last = '\0';
101
102 drm_edid = edid_load(connector, name: edidname);
103
104 kfree(objp: fwstr);
105
106 return drm_edid;
107}
108

source code of linux/drivers/gpu/drm/drm_edid_load.c