[Bug 18564] DVI display detected, but won't turn on (tried latest git)

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=18564

--- Comment #26 from Tyson Whitehead <twhitehead at gmail.com> 2010-10-31 11:41:54 PDT ---
Created an attachment (id=39925)
 View: https://bugs.freedesktop.org/attachment.cgi?id=39925
 Review: https://bugs.freedesktop.org/review?bug=18564&attachment=39925

Diff of 2.6.32 and 2.6.36 constant registers

Result of diffing the output of

- booting up debian kernel 2.6.36 (where it doesn't works) with display
attached,
- doing 100 dumps of the registers between 0x6000-0x8000 after Xorg starts,
- filtering out any registers that do not remain constant

and

- booting up debian kernel 2.6.32 (where it works) with display attached,
- doing 100 dumps of the registers between 0x6000-0x8000 after Xorg starts,
- filtering out any registers that do not remain constant

attached.

I looked the variable ones up in AMDs register guide, and the only non-memory
region register differences seem to be all centered on TMDSA.  They are (not
working vs working)

7880 - 10001000 vs 10001001 (TMDSA_ENABLE off vs on)
7894 - 02000000 vs 00000000 (TMDSA_TEMPORAL_DITHER_RESET on vs off)
78dc - 00000000 vs 00000001 (TMDSA_DSYNSEL off vs on)
7904 - 00000000 vs 00001f00
(TMDSA_{TX1_ENABLE,LNKC1EN,LNKD10EN,LNKD11EN,LNKD12EN} off vs on)
7910 - 00000032 vs 00000031 (TMDSA_PPL_{ENABLE,RESET} off and on vs on and off)

I then booted up under 2.6.36 (the newer not working kernel) and checked that

- writing the 2.6.32 values out to these registers turns on my display,
- writing any of 7880, 7904 and 7910 back to their 2.6.36 values turns it off
again, and
- writing either 7894 or 78dc back to their 2.6.36 values has no effect.

Cheers!  -Tyson

-- 
Configure bugmail: https://bugs.freedesktop.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.