81 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2 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 11static 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 52err_drm_dev_exit:53 drm_dev_exit(idx);54err_kfree:55 kfree(read_buff);56 return ret;57}58 59bool 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 been70 * connected. We consider anything else a connection.71 */72 return !mem_is_zero(hdr, sizeof(hdr));73}74 75const 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