about_radeon_dma

[llittle了了]

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??

      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
 		 	   		  
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