I am working on device driver (my first Linux driver!) for a PCI card
which has a PCI-PCI bridge (DEC 21150) and 4 ethernet controllers on the
other side of the bridge.
Linux Bios has recognized all the PCI devices including the bridge
correctly.
I am also able access all the PCI configuration registers of all the
devices through code. I could initialize all the devices. The devices
are able to raise interrupts.
The problem is the device is not able to write to the system memory area
allocated by kmalloc(). According to the ethernet controller data sheet
the device should write (through bus mastering) the messages to the area
allocated by CPU before raising interrupt. I am finding too frequent
master aborts whenver the device should write to the system area. I am
not able to see the message area changed anytime.
I have not configured the PCI-PCI bridge in my code. I let the BIOS to
look after it. Should I configure bridge also? Can bridge foul the
messages sent by the devices by bus mastering?
I will be grateful if anybody gives some insight in to this.
Thanks in advance,
Veeresh
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