07:57 <lynxeye> mntirc: Actually I know what this is: it's a corner case where swiotlb kicks in unexpectedly and interferes with coherence of the shared TS buffer. I bet you are unable to reproduce this issue when limiting the system RAM to 3GB.

07:58 <lynxeye> Might also explain some of the issues you are seeing on i.MX8MQ...

08:17 <mntirc> lynxeye: oh wow ok! wouldn't have thought in that direction. is the TS buffer in CMA?

08:27 <lynxeye> As the TS buffer is smaller than a page in a lot of cases, it is mostly allocated outside CMA.

08:39 <mntirc> ah!