[Intel-gfx] [PATCH] drm/i915: make user mode sync polarity setting explicit

[Chris Wilson]

On Tue, Jul 30, 2013 at 01:36:32PM +0300, Imre Deak wrote:
> Userspace can pass a mode with an unspecified vsync/hsync polarity
> setting. All encoders in the Intel driver take this to mean a negative
> polarity setting. The HW readout/state checker code on the other hand
> needs these flags to be explicitly set, otherwise the state checker will
> WARN about the mismatch.
> 
> Get rid of the WARN by making the polarity setting explicit in the
> adjusted mode flags based on the requested mode flags. This will keep
> the existing behavior otherwise.
> 
> Note that we could guess from the other timing parameters whether the
> user wanted a VESA or other standard mode and set the polarity
> accordingly. This is what the NV driver does
> (drivers/gpu/drm/nouveau/dispnv04/crtc.c), but I think that's not very
> exact and would change the existing behavior of the Intel driver.

Right, don't guess. If the user wanted the standard mode, then the flags
would have been taken from the standard modeline.
 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=65442

You can add a tested-by here for qa.
 
> Signed-off-by: Imre Deak <imre.deak at intel.com>
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre