[Bug 86202] Intel/VLV: EDID readout on DP port (with DP display connected) gives random results

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=86202

--- Comment #7 from Egbert Eich <eich at pdx.freedesktop.org> ---

> 
> Ugh. That patch really shouldn't fix EDID reads. But I guess it's possible
> this is another one of those broken monitors that return garbage to AUX
> reads while waking up, and the locking makes the operation slow enoguh that
> the monitor falls back asleep between messages :( Either that or we have
> some nasty bug in our aux code somewhere that causes this. Is it a HP ZR24w?
> 

The monitor is a DELL 2212HM in fact.
I agree, this should not happen even it I2C read out is slowed down
considerably.

> If the problem is widespread and the aux code is not at fault, I'm thinking
> we may want to pursue the idea of waking up the sink around AUX transfers. I
> did think about doing that at some point. The main complication is making
> sure the sink doesn't get turned off when it should remain on. So maybe a
> ref count is needed, or maybe we have enough locking in place to make sure
> we can just return the sink to the same power state where we found it.

Right. Maybe you have seen the discussion Daniel and I had on the intel-gfx at .
I had a really simplistic approach but Daniel was afraid that this will not
scale when adding more DP AUX transfers.
So implementing this the proper way is actually on my TODO. I didn't get to it,
yet.

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