about_radeon_dma

[llittle了了]

Thanks for you reply!

I use PCI――MMIO to access VRAM and GTT areas. And for ring_buffer, it alloced from the vmalloc―area and vmap to the physical address using page table. 

 If  enable the radeon_benchmark, it first to prepare the dma channel. "set_tex_resource(), set_render_target(), cp_set_surface_sync()" ,such functions only write ring_buffer. The ring_buffer is vma-area, even it map to physical area. But for radeon_card, how it know the physical-area??  

 The question is same to the SCRACH test, ring_test. Why I write into ring_buffer,then the card register will know the value "deadbeef" ??

Do I not understand the real card work?  ring_test??


> Date: Wed, 13 Jun 2012 09:57:28 -0400
> From: konrad.wilk at oracle.com
> To: sizhiying at hotmail.com
> CC: dri-devel at lists.freedesktop.org
> Subject: Re: about_radeon_dma
> 
> On Wed, Jun 13, 2012 at 09:44:19AM +0800, llittle了了 wrote:
> > 
> > HI,all
> >       Now, my lab is using radeon_ati card。And, I need ati_card dma function。But, I do not clear that how the ati card know the dma address which alloced by kernel??
> 
> By using the PCI API.
> 
> > 
> 
> >       Can any kernel drivers for radeon card give me some advise or explain the answer? 
> > 
> >       I have read the radeon driver in kernel (/driver/gpu/drm/randeon/xxx ）and the TTM manager. So, as I know, If I use GFP_KERNEL sign to alloc memory, the radeon_card work right, but any other palce ,it failed. Why and how this happened?
> >       Is there any way to tell the dma address and ring buffer address in kernel to the radeon_card ?
> > 
> >      It`s so confused! Hope for your answer! 
> >  
> > 
> > Thanks so much!
> > zhiyig Si
> >  		 	   		  
> 
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/dri-devel
> 
 		 	   		  
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