Created attachment 17967 [details] [review]
the patch (against 6.8.0) which fixes the issue.

Since the version of 6.7.191, the switch from X to VT console (Ctrl-Alt-Fn) takes up to 6 seconds (instead of 1 seconds before).

The monitor is "Flatron795FT Plus" (some old CRT display),
the card is "ATI Technologies Inc Radeon RV100 QY [Radeon 7000/VE]",
it is dual-head card, but only one port is in use.

The console image appears fast as before (about 1 sec delay), but without "the final flip somewhere in monitor". Such a flip occurs only after 5-6 seconds, and during this period of time the console shivers.


Fortunately, I casually managed to find the solution. It looks strange, but the reason seems to be the uncommenting one of the previously commented out "usleep(100000);" delays...


Consider src/radeon_driver.c:RADEONRestore() : there is a fragment:

#if 1
    /* Temp fix to "solve" VT switch problems.  When switching VTs on
     * some systems, the console can either hang or the fonts can be
     * corrupted.  This hack solves the problem 99% of the time.  A
     * correct fix is being worked on.
     */
    usleep(100000);
#endif

In the versions before 6.7.x it was disabled (was "#if 0"), but now enabled.

When I change it back to "#if 0", the issue disappears. Additionally, I have experienced a little, and have found that on my system "usleep(80000)" is still OK, but usleep with >= 90000 causes the issue.


I can perform any additional tests, logs etc. if needed.