Re: [intel-agp] Rewrite GTT on resume

[Andrew Morton <akpm@linux-foundation.org>]

On Tue, 03 Jun 2008 20:41:20 -0700
Keith Packard <keithp@keithp.com> wrote:

> On my Intel chipset (965GM), the GTT is entirely erased across
> suspend/resume. This patch simply re-plays the current mapping at resume
> time to restore the table. 
> 
> I noticed this once I started relying on persistent GTT mappings across
> VT switch in our GEM work -- the old X server and DRM code carefully
> unbind all memory from the GTT on VT switch, but GEM does not bother.
> 
> I placed the list management and rewrite code in the generic layer on
> the assumption that it will be needed on other hardware, but I did not
> add the rewrite call to anything other than the Intel resume function.
> 
> 
> commit 1233057731935fb5e9fd115d3d2985802ab636c8
> Author: Keith Packard <keithp@keithp.com>
> Date:   Tue Jun 3 20:34:54 2008 -0700
> 
>     [INTEL-AGP] Re-write GATT on resume
>     
>     Keep a list of current GATT mappings. At resume time, rewrite them into the
>     GATT. This is needed on Intel (at least) as the entire GATT is cleared
>     across suspend/resume.

Please send a signed-off-by:?

> diff --git a/drivers/char/agp/agp.h b/drivers/char/agp/agp.h
> index c69f795..253f56f 100644
> --- a/drivers/char/agp/agp.h
> +++ b/drivers/char/agp/agp.h
> @@ -148,6 +148,8 @@ struct agp_bridge_data {
>  	char minor_version;
>  	struct list_head list;
>  	u32 apbase_config;
> +	/* list of agp_memory mapped to the aperture */
> +	struct list_head mapped_list;
>  };

Is it safe to use this without locking?