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 #include <drm/drm_print.h> 8 9 #include "udl_drv.h" 10 #include "udl_edid.h" 11 12 static int udl_read_edid_block(void *data, u8 *buf, unsigned int block, size_t len) 13 { 14 struct udl_device *udl = data; 15 struct drm_device *dev = &udl->drm; 16 struct usb_device *udev = udl_to_usb_device(udl); 17 u8 *read_buff; 18 int idx, ret; 19 size_t i; 20 21 read_buff = kmalloc(2, GFP_KERNEL); 22 if (!read_buff) 23 return -ENOMEM; 24 25 if (!drm_dev_enter(dev, &idx)) { 26 ret = -ENODEV; 27 goto err_kfree; 28 } 29 30 for (i = 0; i < len; i++) { 31 int bval = (i + block * EDID_LENGTH) << 8; 32 33 ret = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0), 34 0x02, (0x80 | (0x02 << 5)), bval, 35 0xA1, read_buff, 2, USB_CTRL_GET_TIMEOUT); 36 if (ret < 0) { 37 drm_err(dev, "Read EDID byte %zu failed err %x\n", i, ret); 38 goto err_drm_dev_exit; 39 } else if (ret < 1) { 40 ret = -EIO; 41 drm_err(dev, "Read EDID byte %zu failed\n", i); 42 goto err_drm_dev_exit; 43 } 44 45 buf[i] = read_buff[1]; 46 } 47 48 drm_dev_exit(idx); 49 kfree(read_buff); 50 51 return 0; 52 53 err_drm_dev_exit: 54 drm_dev_exit(idx); 55 err_kfree: 56 kfree(read_buff); 57 return ret; 58 } 59 60 bool udl_probe_edid(struct udl_device *udl) 61 { 62 u8 hdr[8]; 63 int ret; 64 65 ret = udl_read_edid_block(udl, hdr, 0, sizeof(hdr)); 66 if (ret) 67 return false; 68 69 /* 70 * The adapter sends all-zeros if no monitor has been 71 * connected. We consider anything else a connection. 72 */ 73 return !mem_is_zero(hdr, sizeof(hdr)); 74 } 75 76 const struct drm_edid *udl_edid_read(struct drm_connector *connector) 77 { 78 struct udl_device *udl = to_udl(connector->dev); 79 80 return drm_edid_read_custom(connector, udl_read_edid_block, udl); 81 } 82