[Bug 16890] New: Too long switch to console since 6.7.x

[bugzilla-daemon at freedesktop.org]

http://bugs.freedesktop.org/show_bug.cgi?id=16890

           Summary: Too long switch to console since 6.7.x
           Product: xorg
           Version: 7.3
          Platform: x86 (IA32)
        OS/Version: Linux (All)
            Status: NEW
          Keywords: patch
          Severity: normal
          Priority: medium
         Component: Driver/Radeon
        AssignedTo: xorg-driver-ati at lists.x.org
        ReportedBy: dmitry at butskoy.name
         QAContact: xorg-team at lists.x.org


Created an attachment (id=17967)
 --> (http://bugs.freedesktop.org/attachment.cgi?id=17967)
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.


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