Re: [PATCH 9/9] drm/i915: swizzling support for snb/ivb

From: Eric Anholt <eric@anholt.net>
To: intel-gfx <intel-gfx@lists.freedesktop.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Subject: Re: [PATCH 9/9] drm/i915: swizzling support for snb/ivb
Date: Fri, 11 Nov 2011 08:50:30 -0800	[thread overview]
Message-ID: <87sjluob6x.fsf@eliezer.anholt.net> (raw)
In-Reply-To: <1320931087-1557-10-git-send-email-daniel.vetter@ffwll.ch>

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On Thu, 10 Nov 2011 14:18:07 +0100, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> We have to do this manually. Somebody had a Great Idea.
> 
> Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

People playing with this when not strictly required is scary to me.
Manually swizzling was a world of hurt.  I got to play with things like
"when the management engine is enabled, it carves out the top N MB of
one of the dimms, and the corresponding N MB of the other dimm doesn't
get swizzled, and you lose".

> diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c b/drivers/gpu/drm/i915/i915_gem_tiling.c
> index 861223b..af0a2fc 100644
> --- a/drivers/gpu/drm/i915/i915_gem_tiling.c
> +++ b/drivers/gpu/drm/i915/i915_gem_tiling.c
> @@ -93,8 +93,20 @@ i915_gem_detect_bit_6_swizzle(struct drm_device *dev)
>  	uint32_t swizzle_y = I915_BIT_6_SWIZZLE_UNKNOWN;
>  
>  	if (INTEL_INFO(dev)->gen >= 6) {
> -		swizzle_x = I915_BIT_6_SWIZZLE_NONE;
> -		swizzle_y = I915_BIT_6_SWIZZLE_NONE;
> +		uint32_t dimm_c0, dimm_c1;
> +		dimm_c0 = I915_READ(MAD_DIMM_C0);
> +		dimm_c1 = I915_READ(MAD_DIMM_C1);
> +		dimm_c0 &= MAD_DIMM_A_SIZE_MASK | MAD_DIMM_A_SIZE_MASK;
> +		dimm_c1 &= MAD_DIMM_A_SIZE_MASK | MAD_DIMM_A_SIZE_MASK;
> +		/* Enable swizzling when the channels are populated with
> +		 * identically sized dimms. */
> +		if (dimm_c0 == dimm_c1) {
> +			swizzle_x = I915_BIT_6_SWIZZLE_9_10;
> +			swizzle_y = I915_BIT_6_SWIZZLE_9;
> +		} else {
> +			swizzle_x = I915_BIT_6_SWIZZLE_NONE;
> +			swizzle_y = I915_BIT_6_SWIZZLE_NONE;
> +		}
>  	} else if (IS_GEN5(dev)) {
>  		/* On Ironlake whatever DRAM config, GPU always do
>  		 * same swizzling setup.
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 0a0b6b1..a62fa95 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -327,6 +327,8 @@
>  #define ARB_MODE		0x04030
>  #define   ARB_MODE_SWIZZLE_SNB	(1<<4)
>  #define   ARB_MODE_SWIZZLE_IVB	(1<<5)
> +#define   ARB_MODE_ENABLE(x)	GFX_MODE_ENABLE(x)
> +#define   ARB_MODE_DISABLE(x)	GFX_MODE_DISABLE(x)
>  #define RENDER_HWS_PGA_GEN7	(0x04080)
>  #define BSD_HWS_PGA_GEN7	(0x04180)
>  #define BLT_HWS_PGA_GEN7	(0x04280)

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