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

[Tormod Volden]

On Mon, Nov 7, 2011 at 2:50 PM, Konrad Rzeszutek Wilk
<konrad.wilk at oracle.com> wrote:
> 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?

No, I don't have access to other AGP hardware. Note that this will
only affect the hardware & software/configuration combinations that
currently result in the "0x" message. A web search on this message
shows that also some radeon cards are bitten by this. So testing on
these cards would be welcome.

Tormod


>
>>
>> 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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>