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

[Daniel Vetter]

On Tue, Jun 10, 2014 at 7:27 PM, Jesse Barnes <jbarnes at 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.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch