[Intel-gfx] [PATCH 5/9] drm/i915: CPT/PPT pch dp transcoder workaround

[Paulo Zanoni]

Hi

2012/10/29 Daniel Vetter <daniel at ffwll.ch>:
> On Mon, Oct 29, 2012 at 6:02 PM, Paulo Zanoni <przanoni at gmail.com> wrote:
>> The description of the chicken bit used in the workaround even says that:
>> "Workaround: Enable the override prior to enabling the transcoder.
>> Disable the override after disabling the transcoder".
>>
>> That's why I said we should implement the workaround in
>> intel_enable_transcoder and intel_disable_transcoder: it matches the
>> register description and also matches what I understood from our mode
>> set sequence.
>
> I think that's what my code does, we set it before/after we enable the
> w/a. The difference between my code and your suggestion is that you
> either have to enable this w/a unconditionally, whereas I think we
> should only do this if we will use the dp transcoder on the pch, not
> in general.
>
> I agree that if we decide that this should be done in general, it's
> better done together with the other pch enable/disable stuff.

LPT does not have DP and it still requires the workaround. Check HSW
doc "Sequence for CRT port", step 26 on enable path (inside "enable
transcoder") and step 11 on disable path (inside "disable
transcoder").

> -Daniel
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch



-- 
Paulo Zanoni