[Bug 16055] Blank screen with Radeon 9600 / RV350

[bugzilla-daemon at freedesktop.org]

http://bugs.freedesktop.org/show_bug.cgi?id=16055





--- Comment #16 from Alex Deucher <agd5f at yahoo.com>  2009-09-01 10:13:02 PST ---
(In reply to comment #14)

> i2c write: 0xe, 0x0
> (EE) RADEON(0): Unable to write to DVO Slave 112.
> i2c write: 0x8, 0x39
> (EE) RADEON(0): Unable to write to DVO Slave 112.
> i2c write: 0x9, 0x38
> (EE) RADEON(0): Unable to write to DVO Slave 112.
> i2c write: 0xa, 0x90
> (EE) RADEON(0): Unable to write to DVO Slave 112.
> i2c write: 0xc, 0x89
> (EE) RADEON(0): Unable to write to DVO Slave 112.
> i2c write: 0x33, 0x0
> (EE) RADEON(0): Unable to write to DVO Slave 112.
> i2c write: 0xd, 0x0
> (EE) RADEON(0): Unable to write to DVO Slave 112.
> 
> Might these messages be related to what I'm seeing, or should I look elsewhere?

The driver isn't able to communicate with the tmds controller which is probably
the problem.  Accessing the external tmds only seems to work on some cards
using the hw i2c controller rather than bit-banging the gpios directly.

> if (IS_R300_VARIANT) {
>   ...
> #if 0
>   if (mode->Clock > 165000)
>      save->fp2_gen_cntl |= R300_FP2_DVO_DUAL_CHANNEL_EN;
> #endif
> }
> 
> Is there an explanation for why those lines are commented out? It sounds like
> that bit might be exactly what I need. But, again, I'd like to get 1280x800
> working before working on 2560x1600.)
> 

You might need them, it depends on how the tmds controller is connected to the
DVO port. There are 3 possible combinations:
SDR single channel (data rate 165 Mhz, port width 12 bits)
DDR single channel (data rate 330 Mhz, port width 12 bits)
SDR dual   channel (data rate 330 Mhz, port width 24 bits)

Relevant bits in FP2_GEN_CNTL:
R200_FP2_DVO_RATE_SEL_SDR selects SDR or DDR
R300_FP2_DVO_DUAL_CHANNEL_EN selects DVO channels

In your case, I'd try DDR single channel or SDR dual channel.


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