suspend to RAM - sleep mode - issue with Linux Mint 20.3

After an upgrade to Linux Mint 20.3 from 19.3, the Macbook was showing a garbled screen when waking up from sleep - i.e. suspend to RAM had some issue, probably with the graphics card. The suspend would also take 1 to 3 minutes to complete, with the fan being on for that time with a blank screen. Ctrl+Option+Fn+F2 was allowing a text-mode terminal to be opened, and syslog showed "Buffer eviction failed" before the suspend was taking effect.

 

After waking up, the display driver nouveau would complain of invalid op-code.

At first, I thought it might have something to do with the two displays being detected on the Macbook as mentioned on this post,
https://hnsws.blogspot.com/2021/03/linux-mint-workspace-size.html
since I had mirrored displays instead of disabling one display. But even after disabling one display, the same issue continued. 

Googling found that this is a known issue, 213617 – Suspend to ram (STR) fails with nouveau driver ([TTM] Buffer eviction failed)

The workaround was, as that thread suggested, adding the kernel parameter  init_on_alloc=0 on boot. Since I use refind to boot, in my case, the adding of the kernel parameter was done by editing the /boot/refind_linux.conf as in my previous post,
https://hnsws.blogspot.com/2021/08/verbose-display-while-booting-with.html

After doing that, I could check the parameters passed to the kernel in various ways as listed here,
https://www.cyberciti.biz/faq/display-view-linux-kernel-parameters-for-booted/

like 

dmesg | grep "Command line"

[    0.000000] Command line: \\boot\vmlinuz-5.4.0-113-generic root=UUID=65c50557-my-disk-uuid-c7b5d84509d2 ro init_on_alloc=0 initrd=boot\initrd.img-5.4.0-113-generic

And now suspend to RAM works.