On Tue, Jan 06, 2015 at 10:07:58PM -0800, Keith Packard wrote:
- PGP Signed by an unknown key
Linus Torvalds torvalds@linux-foundation.org writes:
it looks like the beginning is the same, but then it just turns to all ones at a random point (even *within* a byte).
Looks like the EDID ROM is dropping off the i2c bus in the middle of the transfer. Wonder if it's being 'clever' if things go too slowly at some point, or if there's a bug in the DDC code that's in use.
FWIW, I've seen that exact symptom on some monitors when the +5V pin on the DVI or HDMI cable from the GPU isn't enabled (or isn't providing enough current). Some monitors power the i2c/edid/DDC logic from that +5V either exclusively or when in the DPMS off state, and the i2c chip will just stop responding after a few cycles if not provided sufficient power.
- Robert