[Intel-gfx] Breaking suspend/resume by the Pipe A quirk

[Thomas Richter]

Am 02.06.2014 10:27, schrieb Daniel Vetter:
>
>
> Can you go right ahead and please submit this as a patch?

Certainly, but I would prefer to get more information on this. Even 
though the R31 *also* works without the pipe A quirk, I am not sure it 
does work on all other hardware configurations.

There is, however, an important difference between the R31 and the 
S6010: The R31 uses two independent display pipes for the generating the 
display, LVDS for the internal and VGA for the external display. As a 
result, frame rates and resolutions can be different between the two 
outputs.

The S6010, however, seems to use a single pipe design, with the internal 
display connected via DVI (not LVDS!) and the external by VGA. This has 
the unfortunate side effect that I cannot set the resolutions of 
internal and external display independently. Any attempt to modify the 
external resolution while using the internal screen results in an "no 
crtc found for output VGA1" when using xrandr. (Not quite sure what this 
means, but I believe that the VGA output is simply a duplicate of the 
DVI output, and the two are probably connected through a bios-switchable 
bridge chip).

Thus, I would *prefer* to be conservative and only disable the pipe_A 
quirk only in situations where there is a single display pipe (as in the 
S6010) and, just to be on the safe side, keep it enabled in dual-pipe 
(as in R31) configurations.

Now I wonder how I could possibly distinguish between the two. Could you 
please provide some pointers?

Greetings,
	Thomas