Understanding kdrive ati driver UploadToScreen function.

Abhinav Duggal abhinavduggal at gmail.com
Thu May 3 01:31:55 PDT 2007

Hi all,
I was going through ati kdrive driver.The UploadToScreen gets a src pointer
to the memory region to copy to the destination.But this address is a
virtual space address.This address is used as follows to perform the upload
ATIUploadToScreen(PixmapPtr pDst, char *src, int src_pitch)
//code from  hw/kdrive/ati_draw.c
  OUT_RING(((CARD32 *)src)[i]);
How does sga accelerator use this address for copying.To my knowledge
graphics accelerator does not have any knowledge of the this virtual
address.The ati graphics  accelerator needs a physical address to perform
the copy.How is this done?Correct me if i am wrong anywhere.I am not very
clear about what is this DMA being used for.
Actually, I have a similar situation.I am writing a kdrive driver for my
graphics card.And i need a physical address corresponding to this virtual
address which i will feed to my graphics accelerator.Please help.
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