Date: Fri, 30 Sep 2005 12:14:19 +0530 From: rashmi ns <nsrashmi@gmail.com> To: freebsd-hackers@freebsd.org Subject: request:help reqd in using bus_dma functions Message-ID: <9f9993160509292344l51ee40c3o5baef7b80ce222de@mail.gmail.com>
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hello group ,
I am writing a network driver where in have created tags and maps for
tx_desc of transmit-q-size by using these functions .
1. bus_dma_tag_create
2. bus_dmamap_create
3.bus_dmamem_alloc
struct xxxx_tx_desc {
DWORD data_buff;
DWORD cvbcnxt;
DWORD channel_no;
DWORD pend_desc;
};
For a packet to be transmitted a packet's address should be placed in
tx_desc_q 's DWORD data_buff field and update the rest of the fields .Then
h/w detects the presence of the packet and tranmits the packet
now to test I want to load a buffer like (char buff[50])in tx_q space can
any one tell me in which order I can use bus_dma functions .I have gone th'
docs but not very sure as I'm writing n/w drivers for the first time .I'm
not clear with the dma concepts . I'm getting confused kindly help
Now should I use bus_dmamap_load(bus_dma_tag_t dmat, bus_dmamap_t map, voi=
d
*buf, bus_size_t buflen, bus_dmamap_callback_t *callback,void *callback_arg=
,
int flags);
I'm not getting what callback func should to how to get the mapped address
and place into tx_desc_q 's
Thanks and regards,
Member
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