# ddcutil probe --bus 7 VCP (aka MCCS) version for display is undetected or less than 2.0. Interpretation may not be accurate. EDID version: 1.4 Mfg id: APP, model: iMac, sn: ... How display reports unsupported feature: Capabilities for display on bus /dev/i2c-7 Scanning all VCP feature codes for display Display_Handle[i2c-7: fd=3] VCP code 0x02 (New control value ): Maximum retries exceeded VCP code 0x03 (Soft controls ): Maximum retries exceeded VCP code 0x07 (Unknown feature ): Maximum retries exceeded VCP code 0x09 (Unknown feature ): Maximum retries exceeded VCP code 0x0b (Color temperature increment ): Maximum retries exceeded VCP code 0x0c (Color temperature request ): Maximum retries exceeded VCP code 0x0d (Unknown feature ): Maximum retries exceeded VCP code 0x0e (Clock ): Maximum retries exceeded VCP code 0x0f (Unknown feature ): Maximum retries exceeded VCP code 0x10 (Brightness ): Maximum retries exceeded VCP code 0x11 (Flesh tone enhancement ): Maximum retries exceeded VCP code 0x12 (Contrast ): Maximum retries exceeded VCP code 0x13 (Backlight control ): Maximum retries exceeded VCP code 0x14 (Select color preset ): Maximum retries exceeded VCP code 0x15 (Unknown feature ): Maximum retries exceeded VCP code 0x16 (Video gain: Red ): Maximum retries exceeded VCP code 0x17 (User color vision compensation): Maximum retries exceeded VCP code 0x18 (Video gain: Green ): Maximum retries exceeded VCP code 0x19 (Unknown feature ): Maximum retries exceeded VCP code 0x1a (Video gain: Blue ): Maximum retries exceeded VCP code 0x1b (Unknown feature ): Maximum retries exceeded VCP code 0x1c (Focus ): Maximum retries exceeded VCP code 0x1d (Unknown feature ): Maximum retries exceeded VCP code 0x1e (Auto setup ): Maximum retries exceeded VCP code 0x1f (Auto color setup ): Maximum retries exceeded VCP code 0x20 (Horizontal Position ): Maximum retries exceeded VCP code 0x21 (Unknown feature ): Maximum retries exceeded VCP code 0x22 (Horizontal Size ): Maximum retries exceeded VCP code 0x23 (Unknown feature ): Maximum retries exceeded VCP code 0x24 (Horizontal Pincushion ): Maximum retries exceeded VCP code 0x25 (Unknown feature ): Maximum retries exceeded VCP code 0x26 (Horizontal Pincushion Balance ): Maximum retries exceeded VCP code 0x27 (Unknown feature ): Maximum retries exceeded VCP code 0x28 (Horizontal Convergence ): Maximum retries exceeded VCP code 0x29 (Horizontal Convergence M/G ): Maximum retries exceeded VCP code 0x2a (Horizontal Linearity ): Maximum retries exceeded VCP code 0x2b (Unknown feature ): Maximum retries exceeded VCP code 0x2c (Horizontal Linearity Balance ): Maximum retries exceeded VCP code 0x2d (Unknown feature ): Maximum retries exceeded VCP code 0x2e (Gray scale expansion ): Maximum retries exceeded VCP code 0x2f (Unknown feature ): Maximum retries exceeded VCP code 0x30 (Vertical Position ): Maximum retries exceeded VCP code 0x31 (Unknown feature ): Maximum retries exceeded VCP code 0x32 (Vertical Size ): Maximum retries exceeded VCP code 0x33 (Unknown feature ): Maximum retries exceeded VCP code 0x34 (Vertical Pincushion ): Maximum retries exceeded VCP code 0x35 (Unknown feature ): Maximum retries exceeded VCP code 0x36 (Vertical Pincushion Balance ): Maximum retries exceeded VCP code 0x37 (Unknown feature ): Maximum retries exceeded VCP code 0x38 (Vertical Convergence ): Maximum retries exceeded VCP code 0x39 (Vertical Convergence M/G ): Maximum retries exceeded VCP code 0x3a (Vertical Linearity ): Maximum retries exceeded VCP code 0x3b (Unknown feature ): Maximum retries exceeded VCP code 0x3c (Vertical Linearity Balance ): Maximum retries exceeded VCP code 0x3d (Unknown feature ): Maximum retries exceeded VCP code 0x3e (Clock phase ): Maximum retries exceeded VCP code 0x3f (Unknown feature ): Maximum retries exceeded VCP code 0x40 (Key Balance ): Maximum retries exceeded VCP code 0x41 (Vertical Parallelogram ): Maximum retries exceeded VCP code 0x42 (Horizontal Trapezoid ): Maximum retries exceeded VCP code 0x43 (Vertical Trapezoid ): Maximum retries exceeded VCP code 0x44 (Tilt (rotation) ): Maximum retries exceeded VCP code 0x45 (Unknown feature ): Maximum retries exceeded VCP code 0x46 (Top Corner ): Maximum retries exceeded VCP code 0x47 (Unknown feature ): Maximum retries exceeded VCP code 0x48 (Top Corner Balance ): Maximum retries exceeded VCP code 0x49 (Unknown feature ): Maximum retries exceeded VCP code 0x4a (Bottom Corner ): Maximum retries exceeded VCP code 0x4b (Unknown feature ): Maximum retries exceeded VCP code 0x4c (Bottom Corner Balance ): Maximum retries exceeded VCP code 0x4d (Unknown feature ): Maximum retries exceeded VCP code 0x4e (Unknown feature ): Maximum retries exceeded VCP code 0x4f (Unknown feature ): Maximum retries exceeded VCP code 0x50 (Unknown feature ): Maximum retries exceeded VCP code 0x51 (Unknown feature ): Maximum retries exceeded VCP code 0x52 (Active control ): Maximum retries exceeded VCP code 0x53 (Unknown feature ): Maximum retries exceeded VCP code 0x54 (Performance Preservation ): Maximum retries exceeded VCP code 0x55 (Unknown feature ): Maximum retries exceeded VCP code 0x56 (Horizontal Moire ): Maximum retries exceeded VCP code 0x57 (Unknown feature ): Maximum retries exceeded VCP code 0x58 (Vertical Moire ): Maximum retries exceeded VCP code 0x59 (6 axis saturation: Red ): Maximum retries exceeded VCP code 0x5a (6 axis saturation: Yellow ): Maximum retries exceeded VCP code 0x5b (6 axis saturation: Green ): Maximum retries exceeded VCP code 0x5c (6 axis saturation: Cyan ): Maximum retries exceeded VCP code 0x5d (6 axis saturation: Blue ): Maximum retries exceeded VCP code 0x5e (6 axis saturation: Magenta ): Maximum retries exceeded VCP code 0x5f (Unknown feature ): Maximum retries exceeded VCP code 0x60 (Input Source ): Maximum retries exceeded VCP code 0x61 (Unknown feature ): Maximum retries exceeded VCP code 0x62 (Audio speaker volume ): Maximum retries exceeded VCP code 0x63 (Speaker Select ): Maximum retries exceeded VCP code 0x64 (Audio: Microphone Volume ): Maximum retries exceeded VCP code 0x65 (Unknown feature ): Maximum retries exceeded VCP code 0x66 (Ambient light sensor ): Maximum retries exceeded VCP code 0x67 (Unknown feature ): Maximum retries exceeded VCP code 0x68 (Unknown feature ): Maximum retries exceeded VCP code 0x69 (Unknown feature ): Maximum retries exceeded VCP code 0x6a (Unknown feature ): Maximum retries exceeded VCP code 0x6b (Backlight Level: White ): Maximum retries exceeded VCP code 0x6c (Video black level: Red ): Maximum retries exceeded VCP code 0x6d (Backlight Level: Red ): Maximum retries exceeded VCP code 0x6e (Video black level: Green ): Maximum retries exceeded VCP code 0x6f (Backlight Level: Green ): Maximum retries exceeded VCP code 0x70 (Video black level: Blue ): Maximum retries exceeded VCP code 0x71 (Backlight Level: Blue ): Maximum retries exceeded VCP code 0x72 (Gamma ): Maximum retries exceeded VCP code 0x73 (LUT Size ): Maximum retries exceeded VCP code 0x74 (Single point LUT operation ): Maximum retries exceeded VCP code 0x75 (Block LUT operation ): Maximum retries exceeded VCP code 0x77 (Unknown feature ): Maximum retries exceeded VCP code 0x78 (EDID operation ): Maximum retries exceeded VCP code 0x79 (Unknown feature ): Maximum retries exceeded VCP code 0x7a (Adjust Focal Plane ): Maximum retries exceeded VCP code 0x7b (Unknown feature ): Maximum retries exceeded VCP code 0x7c (Adjust Zoom ): Maximum retries exceeded VCP code 0x7d (Unknown feature ): Maximum retries exceeded VCP code 0x7e (Trapezoid ): Maximum retries exceeded VCP code 0x7f (Unknown feature ): Maximum retries exceeded VCP code 0x80 (Keystone ): Maximum retries exceeded VCP code 0x81 (Unknown feature ): Maximum retries exceeded VCP code 0x83 (Unknown feature ): Maximum retries exceeded VCP code 0x85 (Unknown feature ): Maximum retries exceeded VCP code 0x86 (Display Scaling ): Maximum retries exceeded VCP code 0x87 (Sharpness ): Maximum retries exceeded VCP code 0x88 (Velocity Scan Modulation ): Maximum retries exceeded VCP code 0x89 (Unknown feature ): Maximum retries exceeded VCP code 0x8a (TV Color Saturation ): Maximum retries exceeded VCP code 0x8c (TV Sharpness ): Maximum retries exceeded VCP code 0x8d (Audio Mute ): Maximum retries exceeded VCP code 0x8e (TV Contrast ): Maximum retries exceeded VCP code 0x8f (Audio Treble ): Maximum retries exceeded VCP code 0x90 (Hue ): Maximum retries exceeded VCP code 0x91 (Audio Bass ): Maximum retries exceeded VCP code 0x92 (TV Black level/Brightness ): Maximum retries exceeded VCP code 0x93 (Audio Balance L/R ): Maximum retries exceeded VCP code 0x94 (Audio Stereo Mode ): Maximum retries exceeded VCP code 0x95 (Window Position(TL_X) ): Maximum retries exceeded VCP code 0x96 (Window Position(TL_Y) ): Maximum retries exceeded VCP code 0x97 (Window Position(BR_X) ): Maximum retries exceeded VCP code 0x98 (Window Position(BR_Y) ): Maximum retries exceeded VCP code 0x99 (Window control on/off ): Maximum retries exceeded VCP code 0x9a (Window background ): Maximum retries exceeded VCP code 0x9b (6 axis hue control: Red ): Maximum retries exceeded VCP code 0x9c (6 axis hue control: Yellow ): Maximum retries exceeded VCP code 0x9d (6 axis hue control: Green ): Maximum retries exceeded VCP code 0x9e (6 axis hue control: Cyan ): Maximum retries exceeded VCP code 0x9f (6 axis hue control: Blue ): Maximum retries exceeded VCP code 0xa0 (6 axis hue control: Magenta ): Maximum retries exceeded VCP code 0xa1 (Unknown feature ): Maximum retries exceeded VCP code 0xa3 (Unknown feature ): Maximum retries exceeded VCP code 0xa4 (Turn the selected window operation on/off): Maximum retries exceeded VCP code 0xa5 (Change the selected window ): Maximum retries exceeded VCP code 0xa6 (Unknown feature ): Maximum retries exceeded VCP code 0xa7 (Unknown feature ): Maximum retries exceeded VCP code 0xa8 (Unknown feature ): Maximum retries exceeded VCP code 0xa9 (Unknown feature ): Maximum retries exceeded VCP code 0xaa (Screen Orientation ): Maximum retries exceeded VCP code 0xab (Unknown feature ): Maximum retries exceeded VCP code 0xac (Horizontal frequency ): Maximum retries exceeded VCP code 0xad (Unknown feature ): Maximum retries exceeded VCP code 0xae (Vertical frequency ): Maximum retries exceeded VCP code 0xaf (Unknown feature ): Maximum retries exceeded VCP code 0xb1 (Unknown feature ): Maximum retries exceeded VCP code 0xb2 (Flat panel sub-pixel layout ): Maximum retries exceeded VCP code 0xb3 (Unknown feature ): Maximum retries exceeded VCP code 0xb4 (Source Timing Mode ): Maximum retries exceeded VCP code 0xb5 (Unknown feature ): Maximum retries exceeded VCP code 0xb6 (Display technology type ): Maximum retries exceeded VCP code 0xb7 (Monitor status ): Maximum retries exceeded VCP code 0xb8 (Packet count ): Maximum retries exceeded VCP code 0xb9 (Monitor X origin ): Maximum retries exceeded VCP code 0xba (Monitor Y origin ): Maximum retries exceeded VCP code 0xbb (Header error count ): Maximum retries exceeded VCP code 0xbc (Body CRC error count ): Maximum retries exceeded VCP code 0xbd (Client ID ): Maximum retries exceeded VCP code 0xbe (Link control ): Maximum retries exceeded VCP code 0xbf (Unknown feature ): Maximum retries exceeded VCP code 0xc0 (Display usage time ): Maximum retries exceeded VCP code 0xc1 (Unknown feature ): Maximum retries exceeded VCP code 0xc2 (Display descriptor length ): Maximum retries exceeded VCP code 0xc3 (Transmit display descriptor ): Maximum retries exceeded VCP code 0xc4 (Enable display of 'display descriptor'): Maximum retries exceeded VCP code 0xc5 (Unknown feature ): Maximum retries exceeded VCP code 0xc6 (Application enable key ): Maximum retries exceeded VCP code 0xc7 (Unknown feature ): Maximum retries exceeded VCP code 0xc8 (Display controller type ): Maximum retries exceeded VCP code 0xc9 (Display firmware level ): Maximum retries exceeded VCP code 0xca (OSD ): Maximum retries exceeded VCP code 0xcb (Unknown feature ): Maximum retries exceeded VCP code 0xcc (OSD Language ): Maximum retries exceeded VCP code 0xcd (Status Indicators ): Maximum retries exceeded VCP code 0xce (Auxiliary display size ): Maximum retries exceeded VCP code 0xd0 (Output select ): Maximum retries exceeded VCP code 0xd1 (Unknown feature ): Maximum retries exceeded VCP code 0xd2 (Asset Tag ): Maximum retries exceeded VCP code 0xd3 (Unknown feature ): Maximum retries exceeded VCP code 0xd4 (Stereo video mode ): Maximum retries exceeded VCP code 0xd5 (Unknown feature ): Maximum retries exceeded VCP code 0xd6 (Power mode ): Maximum retries exceeded VCP code 0xd7 (Auxiliary power output ): Maximum retries exceeded VCP code 0xd8 (Unknown feature ): Maximum retries exceeded VCP code 0xd9 (Unknown feature ): Maximum retries exceeded VCP code 0xda (Scan format ): Maximum retries exceeded VCP code 0xdb (Image Mode ): Maximum retries exceeded VCP code 0xdc (Display Mode ): Maximum retries exceeded VCP code 0xdd (Unknown feature ): Maximum retries exceeded VCP code 0xdf (VCP Version ): Maximum retries exceeded VCP code 0xe0 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xe1 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xe2 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xe3 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xe4 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xe5 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xe6 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xe7 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xe8 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xe9 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xea (Manufacturer Specific ): Maximum retries exceeded VCP code 0xeb (Manufacturer Specific ): Maximum retries exceeded VCP code 0xec (Manufacturer Specific ): Maximum retries exceeded VCP code 0xed (Manufacturer Specific ): Maximum retries exceeded VCP code 0xee (Manufacturer Specific ): Maximum retries exceeded VCP code 0xef (Manufacturer Specific ): Maximum retries exceeded VCP code 0xf0 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xf1 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xf2 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xf3 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xf4 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xf5 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xf6 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xf7 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xf8 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xf9 (Manufacturer Specific ): Maximum retries exceeded VCP code 0xfa (Manufacturer Specific ): Maximum retries exceeded VCP code 0xfb (Manufacturer Specific ): Maximum retries exceeded VCP code 0xfc (Manufacturer Specific ): Maximum retries exceeded VCP code 0xfd (Manufacturer Specific ): Maximum retries exceeded VCP code 0xfe (Manufacturer Specific ): Maximum retries exceeded VCP code 0xff (Manufacturer Specific ): Maximum retries exceeded Unable to read or parse capabilities. Skipping comparison of declared capabilities to observed features Unable to calculate color temperature from VCP features x0B and x0C VCP code 0x14 (Select color preset ): Maximum retries exceeded