[Intel-gfx] [PATCH 2/2] drm/i915/dp: check eDP display control capability registers

[Daniel Vetter]

On Mon, Nov 18, 2013 at 5:31 PM, Thierry Reding
<thierry.reding at gmail.com> wrote:
>> Note that there's already a bit of abstraction for i2c over dp aux, but
>> imo that's at the wrong level. At least reading through i915, gma500 and
>> radeon code there's a lot more we could share with just a dp aux helper
>> library (which then implements useful stuff on top of it).
>
> I have some difficulty envisioning how the helper code can work without
> some sort of driver-specific ops implementation. Currently the helpers
> only use a snapshot of the DPCD to extract information. Eventually we'll
> be bound to modify the DPCD, so some method of writing it back (or a
> subset of it) will be needed. Otherwise the scope of the helper library
> will be somewhat limited.
>
> Once we have the callbacks, the current helpers could be reworked to not
> use a buffer, but rather an "AUX channel object" and access the
> registers directly. If there are concerns about performance, it could
> possibly be implemented as a sort of cache, too. That would make it fast
> to query the status. I don't think it'll be worth the added complexity,
> though.

Oh, my idea is that the dp aux driver callback would at the level of
the intel_dp_aux_ch function in i915/intel_dp.c (gma500 and radeon
have something very similar). That alone would allow us to share a
considerable amount of code. Should have been a bit clearer, I've
discussed this in a bit more detail with Alex many moons ago ...
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch