[PATCH] exa: add EXA_MIXED_PREFER_UTS

[Michel Dänzer]

On Mon, 2009-11-30 at 18:56 +0100, Maarten Maathuis wrote: 
> - Drivers using wfb don't like unneeded cpu fallbacks, allow them to signal this.
> 
> Signed-off-by: Maarten Maathuis <madman2003 at gmail.com>
> ---
>  exa/exa.h       |    6 ++++++
>  exa/exa_accel.c |    6 ++++--
>  2 files changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/exa/exa.h b/exa/exa.h
> index 8c93d15..46552c7 100644
> --- a/exa/exa.h
> +++ b/exa/exa.h
> @@ -769,6 +769,12 @@ typedef struct _ExaDriver {
>   */
>  #define EXA_MIXED_PIXMAPS (1 << 6)
>  
> +/**
> + * EXA_MIXED_PREFER_UTS indicates that cpu access is more costly than DFS,
> + * which might follow UTS.
> + */
> +#define EXA_MIXED_PREFER_UTS (1 << 7)
> +
>  /** @} */
>  
>  /* in exa.c */
> diff --git a/exa/exa_accel.c b/exa/exa_accel.c
> index 1d88acb..b438b1a 100644
> --- a/exa/exa_accel.c
> +++ b/exa/exa_accel.c
> @@ -508,9 +508,11 @@ exaHWCopyNtoN (DrawablePtr    pSrcDrawable,
>  	 *
>  	 * Not taking this path for mixed pixmaps: It could only save one CPU
>  	 * copy between cached memory and risks causing a more expensive
> -	 * DownloadFromScreen later on.
> +	 * DownloadFromScreen later on. Some drivers may prefer a potential
> +	 * DFS to a cpu fallback.
>  	 */
> -	} else if (!(pExaScr->info->flags & EXA_MIXED_PIXMAPS)) {
> +	} else if (!(pExaScr->info->flags & EXA_MIXED_PIXMAPS) ||
> +			(pExaScr->info->flags & EXA_MIXED_PREFER_UTS)) {

(Your indentation doesn't line up again...)

I think PREFER_UTS is too specific. I'm working on similar changes e.g.
in GetImage.

Note that these changes are motivated by a rather special environment
where direct PrepareAccess isn't possible and DownloadFromScreen is very
expensive. Maybe the name of the new flag should reflect that, and the
previous behaviour be restored when the flag isn't set.


-- 
Earthling Michel Dänzer           |                http://www.vmware.com
Libre software enthusiast         |          Debian, X and DRI developer