In mga_drm.h comments indicate that only DSTORG and TEXORG is validated.
I think bit 15 (memreset) of MACCESS should be checked as
"The memreset field must always be set to '0' except under specific conditions
which occur during the reset sequence."
Seems like something which should not be accessible to normal users.
ajax at nwnk dot net,
Do you still experience this issue with newer soft?
Please check the status of your issue.
Freedesktop's Bugzilla instance is EOLed and open bugs are about to be migrated to http://gitlab.freedesktop.org.
To avoid migrating out of date bugs, I am now closing all the bugs that did not see any activity in the past year. If the issue is still happening, please create a new bug in the relevant project at https://gitlab.freedesktop.org/drm (use misc by default).
Sorry about the noise!