Re: [PATCH 2/5] drm/i915: preserve swizzle settings if necessary v3

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Tue, 10 Jun 2014 21:33:27 +0200
Daniel Vetter <daniel@ffwll.ch> wrote:

> On Tue, Jun 10, 2014 at 7:27 PM, Jesse Barnes <jbarnes@virtuousgeek.org> wrote:
> > Yes, that's what I do below... I even added it to the changelog:
> > http://patchwork.freedesktop.org/patch/27223/
> >
> > Did you miss the later hunk in intel_display.c?
> >
> > What we try to do here is enable swizzling if possible, which we can do
> > if no inherited fbs are tiled.
> >
> > So I think I've done exactly what you repeated above, and documented
> > it.  So you're going to need to repeat it with different words so I can
> > understand, if I'm still missing something.
> 
> In swizzle_detect:
> 
> ...
> 
> if (GEN6+) {
> 	if (preserve_bios_swizzle) {
> 		if (I915_READ(DISP_ARB_CTL) & DISP_TILE_SURFACE_SWIZZLING) {
> 			swizzle_x = I915_BIT_6_SWIZZLE_9_10;
> 			...
> 		} else {
> 			swizzle_x = I915_BIT_6_SWIZZLE_NONE;
> 			...
> 		}
> 	} else {
> 		/* existing/old logic to decide about swizzling */
> 	}
> }
> 
> ...
> 
> Plus no shortcut in i915_gem_init_swizzling. Personally I'd also just use
> a small helper function to compute preserve_bios_swizzle instead of
> storing it in dev_priv (since we will only use it at exactly one place),
> but that's a pure style preference.

Doesn't this amount to the same thing?  I.e. we enable it if possible,
otherwise just report it as unswizzled?  So you're just wanting a style
change here?

-- 
Jesse Barnes, Intel Open Source Technology Center