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<DIV><FONT face=新細明體 size=2><SPAN
class=938413313-11112008>Hi,</SPAN></FONT></DIV>
<DIV><FONT face=新細明體 size=2><SPAN
class=938413313-11112008></SPAN></FONT> </DIV>
<DIV><FONT face=新細明體 size=2><SPAN class=938413313-11112008>I am using 2.6.14.5
and MPC8349.</SPAN></FONT></DIV>
<DIV><FONT face=新細明體 size=2><SPAN class=938413313-11112008>I got some DMA
problems with PCI devices.</SPAN></FONT></DIV>
<DIV><FONT face=新細明體 size=2><SPAN class=938413313-11112008>So, I tried to
understand the DMA stuff of linux.</SPAN></FONT></DIV>
<DIV><FONT face=新細明體 size=2><SPAN
class=938413313-11112008></SPAN></FONT> </DIV>
<DIV><FONT face=新細明體 size=2><SPAN class=938413313-11112008>I have one question
about cache coherency.</SPAN></FONT></DIV>
<DIV><FONT face=新細明體 size=2><SPAN class=938413313-11112008>In dma-mapping.h, I
found some functions are defined as NULL.</SPAN></FONT></DIV>
<DIV><FONT face=新細明體 size=2><SPAN class=938413313-11112008>For
example:</SPAN></FONT></DIV>
<DIV><FONT face=新細明體 size=2><SPAN class=938413313-11112008>#define
dma_cache_inv(_start,_size) do { } while (0)<BR>#define
dma_cache_wback(_start,_size) do { } while (0)<BR>#define
dma_cache_wback_inv(_start,_size) do { } while (0)</SPAN></FONT></DIV>
<DIV><FONT face=新細明體 size=2></FONT> </DIV>
<DIV><FONT face=新細明體 size=2><SPAN class=938413313-11112008>#define
__dma_alloc_coherent(gfp, size, handle) NULL<BR>#define
__dma_free_coherent(size, addr) do { } while (0)<BR>#define
__dma_sync(addr, size, rw) do { } while (0)<BR>#define
__dma_sync_page(pg, off, sz, rw) do { } while (0)<BR></SPAN></FONT></DIV>
<DIV><FONT face=新細明體 size=2><SPAN class=938413313-11112008>Does this mean that I
don't need to take care of cache coherency in MPC83xx
platform?</SPAN></FONT></DIV>
<DIV><FONT face=新細明體 size=2><SPAN class=938413313-11112008>So, I could use any
range of memory for DMA transferring and the hardware will take care of the
cache coherency for me?</SPAN></FONT></DIV>
<DIV><FONT face=新細明體 size=2><SPAN
class=938413313-11112008></SPAN></FONT> </DIV>
<DIV><FONT face=新細明體 size=2><SPAN class=938413313-11112008>Thanks a
lot.</SPAN></FONT></DIV>
<DIV><FONT face=新細明體 size=2><SPAN
class=938413313-11112008></SPAN></FONT> </DIV>
<DIV><FONT face=新細明體 size=2><SPAN
class=938413313-11112008>
Jay Chen.</SPAN></FONT></DIV>
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class=938413313-11112008></SPAN></FONT> </DIV></BODY></HTML>