2017 MBP Sleep Issues with USB-C Monitor / Hub

[ferrarr]

Please explain how you power the MBP? Wall outlet -> USBC charger brick -> USBC cord -> then what (hub, LG display). If the USBC cord directly into the MBP works properly with a separate USBC cord to the display, then the issue is the hub within the monitor.

 

[howardc64]

Wall AC -> USB-C Monitor with build-in USB HUB <-> MBP

USB-C monitor provides both charging power and video connection to MBP with single USB-C cable. Ideal setup since M1 MBP has only 2x USB-C ports. If using HDMI, both M1 MBP's USB-C port is used (1 for USB-C -> HDMI, 1 for USB-C charger)

Samsung LS27A600UUNXGO (USB-C monitor with AC/DC adapter built-in) has the problem (MBP sleeps, monitor goes to standby, later MBP charging sound chimes, monitor wakes up, black screen with USB-C no video msg, monitor goes to standby, repeat after a min or two) This behavior seems well documented in multiple posts with Samsung USB-C monitor. Seems firmware (no updates) related.

Dell S2718D (USB-C monitor with external AC/DC adapter) doesn't have this problem. Monitor seems to not shutoff USB-C charging power to MBP during standby.

 

[ferrarr]

But if it works properly with the USBC power adapter AND the USBC to display cable, then the issue is in the hub, and not the Mac or macOS. That's something you should test. Or try using a higher powered power brick to run everything.

 

[howardc64]

But if it works properly with the USBC power adapter AND the USBC to display cable, then the issue is in the hub, and not the Mac or macOS. That's something you should test. Or try using a higher powered power brick to run everything.

yes, clearly problem is with Samsung USB-C monitor. Not MBP or macOS related. USB-C charger + USB-C to HDMI to monitor works fine. Monitor has built-in AC/DC so can't change to higher amp brick. From googling online, seems common problem with Samsung USB-C monitors and USB-C MBs

 

[howardc64]

Here is a detail macOS event analysis with this issue. It can be argued its a macOS problem and/or Samsung monitor problem. But they are basically not cooperating.

Samsung monitor is cycling USB-C charging which wakes up macOS (darkwake) and this kicks off the monitor screen wake, no USB-C video signal, monitor to standby and repeat...

MacBook Pro M1 wakes due to USB-C chargin… - Apple Community

PCs works properly with Samsung USB-C monitors.
macOS works properly with DELL USB-C monitors.

So either Samsung firmware and/or Apple macOS updates to properly coordinate. Meanwhile, only work around is to turn monitor off when macOS goes to sleep. Not quite so user friendly (multiple buttons and multiple presses to turn off)

 

[howardc64]

Found a solution that might work for some cases. Turn sleep off when display off and connected to external power supply. Seems not so bad on M1s as it converges towards iPhone/iPad.

Re: Monitor won't stay off in sleep mode - Page 8 - Samsung Community - 2508160