| commit | 0de009c900e7ebd21097797f723a40813e953879 | |
| author | Chris Wilson <chris@chris-wilson.co.uk> | |
| Tue, 5 Apr 2011 15:04:39 +0000 (5 16:04 +0100) | ||
| committer | Keith Packard <keithp@keithp.com> | |
| Tue, 5 Apr 2011 16:05:34 +0000 (5 09:05 -0700) | ||
| tree | 48a314a677088da01022e7f3ff119353cc55c861 | treesnapshot (tar.gz zip) |
| parent | 7f58aabc369014fda3a4a33604ba0a1b63b941ac | commitdiff |
drm/i915/crt: Remove 0xa0 probe for VGA
This is a moral revert of 6ec3d0c0e9c0c605696e91048eebaca7b0c36695.
Following the fix to reset the GMBUS controller after a NAK, we finally
utilize the 0xa0 probe for a CRT connection. And discover that the code
is broken. Shock.
There are a number of issues, but following a key insight from Dave
Airlie, that 0xA0 is an invalid address on a 7-bit bus (though not if we
were to enable 10-bit addressing), and would look like the EDID port
0x50, it is possible to see where the confusion starts.
In short, a write to 0xA0 is accepted by the GMBUS controller which we
interpreted as meaning the existence of a connection (a slave on the
other end of the wire ACKing the write). That was false.
During testing with a broken GMBUS implementation, which never reset an
earlier NAK, this test always reported a NAK and so we proceeded on to
the next test.
Reported-and-tested-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=35904
Reported-and-tested-by: Riccardo Magliocchetti <riccardo.magliocchetti@gmail.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=32612
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Dave Airlie <airlied@linux.ie>
Signed-off-by: Keith Packard <keithp@keithp.com>
This is a moral revert of 6ec3d0c0e9c0c605696e91048eebaca7b0c36695.
Following the fix to reset the GMBUS controller after a NAK, we finally
utilize the 0xa0 probe for a CRT connection. And discover that the code
is broken. Shock.
There are a number of issues, but following a key insight from Dave
Airlie, that 0xA0 is an invalid address on a 7-bit bus (though not if we
were to enable 10-bit addressing), and would look like the EDID port
0x50, it is possible to see where the confusion starts.
In short, a write to 0xA0 is accepted by the GMBUS controller which we
interpreted as meaning the existence of a connection (a slave on the
other end of the wire ACKing the write). That was false.
During testing with a broken GMBUS implementation, which never reset an
earlier NAK, this test always reported a NAK and so we proceeded on to
the next test.
Reported-and-tested-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=35904
Reported-and-tested-by: Riccardo Magliocchetti <riccardo.magliocchetti@gmail.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=32612
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Dave Airlie <airlied@linux.ie>
Signed-off-by: Keith Packard <keithp@keithp.com>
| drivers/gpu/drm/i915/intel_crt.c | diffblobblamehistory |