PowerPC agpmode issues

[Herminio Hernandez Jr.]

I have been experiencing the same thing with my iBook and PowerBook. 

Sent from my iPhone

> On Feb 4, 2016, at 8:47 PM, Mike <michael.heltne at gmail.com> wrote:
> 
> Hi. 
> Managed to get the Radeon R300 running on mesa 11.1.1 with an old 2013 patch from Michel Dànzer, next problem is of course enabling agpmode, running with pci-mode with radeon.agpmode=-1 works, but is of course slow, and seems to load the cpu a lot.
> 
> Upon initial investigation i could not initially believe agp could be this this broken for this long, until i found this.
>  "committed with Ben Skeggs on Feb 26, 2013"
> https://github.com/DespairFactor/bullhead/commit/650e1203c11354ba84d69ba445abc0efcfe3890a
> http://lxr.free-electrons.com/source/drivers/gpu/drm/nouveau/nouveau_agp.c?v=4.2
> #ifdef __powerpc__
> 		/* Disable AGP by default on all PowerPC machines for
> 		 * now -- At least some UniNorth-2 AGP bridges are
> 		 * known to be broken: DMA from the host to the card
> 		 * works just fine, but writeback from the card to the
> 		 * host goes straight to memory untranslated bypassing
> 		 * the GATT somehow, making them quite painful to deal
> 		 * with...
> 		 */
> 		if (nouveau_agpmode == -1)
> 			return false;
> #endif
>  
>  and now later this: 
> https://github.com/torvalds/linux/blob/master/drivers/gpu/drm/nouveau/nvkm/subdev/pci/agp.c
> #ifdef __powerpc__
> 	/* Disable AGP by default on all PowerPC machines for now -- At
> 	 * least some UniNorth-2 AGP bridges are known to be broken:
> 	 * DMA from the host to the card works just fine, but writeback
> 	 * from the card to the host goes straight to memory
> 	 * untranslated bypassing that GATT somehow, making them quite
> 	 * painful to deal with...
> 	 */
> 	mode = 0;
> #endif
> 
> All seems to point to serious issues had around the time of change to ums to kms and a serious regression hitting the linux kernel? No?
> 
> Cheers
> -Mike
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