drivers/gpu/drm/udl/udl_edid.c

   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
  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
  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
  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 }