[Intel-gfx] [PATCH] drm/i915: Delay disabling of VGA memory until vgacon->fbcon handoff is done

[Daniel Vetter]

On Thu, Sep 05, 2013 at 08:40:52PM +0300, ville.syrjala at linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> When transitioning away from vgacon the system tries to save the
> current contents of the VGA memory, so that it can be cleanly handed
> off to fbcon (or whatever comes afterwards).
> 
> The recent change
> 
>  commit 81b5c7bc8de3e6f63419139c2fc91bf81dea8a7d
>  Author: Alex Williamson <alex.williamson at redhat.com>
>  Date:   Wed Aug 28 09:39:08 2013 -0600
> 
>     i915: Update VGA arbiter support for newer devices
> 
> caused i915 to disable VGA memory decode for the IGD when i915 is
> initializing. Unfortunately that happens before the vgacon->fbcon
> handoff so vgacon_save_screen() will read out all ones from the
> VGA memory.
> 
> After the handoff fbcon will inherit the bogus state from vgacon,
> and pre-fills the fb with matching contents. The end result is
> a white rectangle in the top left corner of the screen, the size
> of which matches the now inactive VGA console.
> 
> To remedy the situation delay the disabling of VGA memory until
> the vgacon->fbcon handoff has happened.
> 
> Also rename i915_enable_vga to i915_enable_vga_mem to make
> the relationship between these functions clearer.
> 
> Cc: Alex Williamson <alex.williamson at redhat.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

Picked up for -fixes, thanks for the patch.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch