Re: Query about PCI base address registers

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Hi Ulka,

Generally, the PCI configuration details are supplied by the PCI Card manufactures where they can explain all those details which you asked. So, try to get the PCI User Manual for the PCI card that you are working. In that user manual, you find all the information.

Regarding the DMA, we need to start by setting one of the bits in DMA registers. This also explained in the PCI user manual.

Do you still need any other information please let me know as I worked on couple of projects which are based on PCI cards.

Regards,
Srinivas.



On Thu, Dec 12, 2013 at 5:53 PM, Ulka Vaze <ulka.vaze@xxxxxxxx> wrote:
Hi,

   In PCI configuration space there are 6 registers BAR0-5 which can
hold the ioaddress or memory address used by card.
However my question is - how will we know which BAR register contain
ioaddress  and which contain memory ? and How many of them contain the
addresses. I mean shall we start reading from bar0 to 5 all to find it
?
If card  has 3 ports and one memory region  will it be in bar0 or bar1 or bar2 ?

Second is on PCI card we set it as bus master for DMA  in probe
function and also allocates buffer. So when is DMA  actually initiated
by it ?

Please can anybody clarify.

Thanks,
-Ulka




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