From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alan Cox <alan-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org>
Subject: Re: [RFC 4/4] drm: Add NVIDIA Tegra support
Date: Wed, 11 Apr 2012 15:52:37 +0100
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To: Thierry Reding <thierry.reding-RM9K5IK7kjKj5M59NBduVrNAH6kLmebB@public.gmane.org>
Cc: Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>, devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Daniel Vetter <daniel-/w4YWyX8dFk@public.gmane.org>, Colin Cross <ccross-z5hGa2qSFaRBDgjK7y7TUQ@public.gmane.org>, Jon Mayo <jmayo-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
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> Maybe your question is answered by my reply to Alan's comment. The mapping
> is actually done to get a linear view for the display controller which
> doesn't support SG transfers. The kernel and user-space already have virtual
> linear buffers.

The framebuffer currently needs a physically contiguous map for the
console devices. Well you could vmap them but that is pretty hideous on a
32bit platform with 32bit 1080p display plugged into it!

Alan