[PATCH] agp: Enable all supported rates for graphic cards

[Konrad Rzeszutek Wilk]

On Sun, Nov 06, 2011 at 04:03:21PM +0100, Tormod Volden wrote:
> From: Tormod Volden <debian.tormod at gmail.com>
> 
> Some cards report that they support only 4x, in which case they
> should support 2x and 1x as well, according to the AGP spec.

Have you tested it on other hardware besides your KN133?

> 
> Otherwise a requested 1x or 2x rate will result in 0 being set:
> 
> agpgart-via 0000:00:00.0: putting AGP V2 device into 0x mode
> 
> For instance ProSavage KN133 [5333:8d02] only reports 4x.
> 
> Signed-off-by: Tormod Volden <debian.tormod at gmail.com>
> ---
>  drivers/char/agp/generic.c |   18 ++++++++++++++++++
>  1 files changed, 18 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/char/agp/generic.c b/drivers/char/agp/generic.c
> index b072648..c5d04e5 100644
> --- a/drivers/char/agp/generic.c
> +++ b/drivers/char/agp/generic.c
> @@ -526,6 +526,24 @@ static void agp_v2_parse_one(u32 *requested_mode, u32 *bridge_agpstat, u32 *vga_
>  		break;
>  	}
>  
> +	/* Some graphic cards report they only support 4x, however the AGP 2.0 spec
> +	 * (section 4.1.1) says components must support the lower speeds as well.
> +	 */
> +	switch (*vga_agpstat & 7) {
> +	case 4:
> +		*vga_agpstat |= (AGPSTAT2_2X | AGPSTAT2_1X);
> +		printk(KERN_INFO PFX "Graphics card claims to only support x4 rate. "
> +			"Fixing up support for x2 & x1\n");
> +		break;
> +	case 2:
> +		*vga_agpstat |= AGPSTAT2_1X;
> +		printk(KERN_INFO PFX "Graphics card claims to only support x2 rate. "
> +			"Fixing up support for x1\n");
> +		break;
> +	default:
> +		break;
> +	}
> +
>  	/* Check the speed bits make sense. Only one should be set. */
>  	tmp = *requested_mode & 7;
>  	switch (tmp) {
> -- 
> 1.7.5.4
> 
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