Well!... you can manage any way you want.
1) You can store the virtual address in the DpRAM, and convert to physical (should I say DMA mapped address) and then pass it on to the device under consideration here. 2) Other way would be... store the physical address in DpRAM. Use that address for the device, and convert to virtual before you use it in the code. My preference is for first option. - Siva ________________________________ From: suresh suresh [mailto:[EMAIL PROTECTED] Sent: Monday, July 16, 2007 10:59 PM To: Scott Wood Cc: Siva Prasad; [email protected] Subject: Re: Linuxppc-embedded Digest, Vol 35, Issue 33 Thanks.... MPC8280 has internal memory space which contains Dualport(Dp) RAM. In the DpRAM we allocate some tables and these has to store pointer of the buffers which are allocated in external memory. Core will use this pointer to access the buffers, basically these buffers are used for DMA. Using IMMR register we can get physical address of the internal memory. Now can I store the address return by the kmalloc() function? or I should convert it into physical? Please help me how to resove this address translation. Regards, Suresh On 7/16/07, Scott Wood <[EMAIL PROTECTED]> wrote: Siva Prasad wrote: > It returns kernel virtual address. If you use this buffer space for DMA, > please use appropriate flags. You may use __pa(address) or > virt_to_phys() to convert virtual to physical. No, you may not -- physical and DMA addresses are not always identical. Use the DMA mapping API. -Scott
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