1 // SPDX-License-Identifier: GPL-2.0-only
2
3 #include <linux/string.h>
4
5 #include <drm/drm_drv.h>
6 #include <drm/drm_edid.h>
7
8 #include "udl_drv.h"
9 #include "udl_edid.h"
10
udl_read_edid_block(void * data,u8 * buf,unsigned int block,size_t len)11 static int udl_read_edid_block(void *data, u8 *buf, unsigned int block, size_t len)
12 {
13 struct udl_device *udl = data;
14 struct drm_device *dev = &udl->drm;
15 struct usb_device *udev = udl_to_usb_device(udl);
16 u8 *read_buff;
17 int idx, ret;
18 size_t i;
19
20 read_buff = kmalloc(2, GFP_KERNEL);
21 if (!read_buff)
22 return -ENOMEM;
23
24 if (!drm_dev_enter(dev, &idx)) {
25 ret = -ENODEV;
26 goto err_kfree;
27 }
28
29 for (i = 0; i < len; i++) {
30 int bval = (i + block * EDID_LENGTH) << 8;
31
32 ret = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
33 0x02, (0x80 | (0x02 << 5)), bval,
34 0xA1, read_buff, 2, USB_CTRL_GET_TIMEOUT);
35 if (ret < 0) {
36 drm_err(dev, "Read EDID byte %zu failed err %x\n", i, ret);
37 goto err_drm_dev_exit;
38 } else if (ret < 1) {
39 ret = -EIO;
40 drm_err(dev, "Read EDID byte %zu failed\n", i);
41 goto err_drm_dev_exit;
42 }
43
44 buf[i] = read_buff[1];
45 }
46
47 drm_dev_exit(idx);
48 kfree(read_buff);
49
50 return 0;
51
52 err_drm_dev_exit:
53 drm_dev_exit(idx);
54 err_kfree:
55 kfree(read_buff);
56 return ret;
57 }
58
udl_probe_edid(struct udl_device * udl)59 bool udl_probe_edid(struct udl_device *udl)
60 {
61 u8 hdr[8];
62 int ret;
63
64 ret = udl_read_edid_block(udl, hdr, 0, sizeof(hdr));
65 if (ret)
66 return false;
67
68 /*
69 * The adapter sends all-zeros if no monitor has been
70 * connected. We consider anything else a connection.
71 */
72 return !mem_is_zero(hdr, sizeof(hdr));
73 }
74
udl_edid_read(struct drm_connector * connector)75 const struct drm_edid *udl_edid_read(struct drm_connector *connector)
76 {
77 struct udl_device *udl = to_udl(connector->dev);
78
79 return drm_edid_read_custom(connector, udl_read_edid_block, udl);
80 }
81