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Re: FW: Db1500 PCI Auto Scan Question, bus master operation

To: fpga dsp <>
Subject: Re: FW: Db1500 PCI Auto Scan Question, bus master operation
From: Pete Popov <>
Date: 12 Jun 2003 10:12:01 -0700
Cc: Tom Cernius <>, Linux MIPS mailing list <>
In-reply-to: <>
Organization: MontaVista Software
Original-recipient: rfc822;
References: <>
On Wed, 2003-06-11 at 19:15, fpga dsp wrote:
> Hi,
> I am using kernel 2.4.20-pre6 version on db1500 and
> having problem with PCI card as bus master. Basicly,
> the kernel can recognize the card and assign into
> 0x40000000 address region, irq is 1. Now that is
> really strange, stty1 using irq 1 as well. Are they
> the same or different. 

There's no UART1 on the Au1500 so you don't have to worry about that
interrupt, even though it's defined in the .h file for the Au1000.

> However ,the problem is that
> after setup the device and trigger it, it should go
> and fetch the descriptor and will fetch the content
> pointed by that descriptor afterward but it only fetch
> the descriptor and quiet. I am even try to trigger it
> again by write into it register mapped on PCI memory
> region but after the first trigger, the second trigger
> doesn't appear on pci bus analyzer at all. 

> Another issues, it when I look at au1000_eth.c device
> driver , dma_alloc() function allocate a DMAable
> buffer in KSEG0 region but pci_alloc_consistent return
> in KSEG1 region. So which one is right?

Right for what? KSEG0 works because the cache is coherent. But due to a
pci coherency bug, I think for a new device driver that's a pci bus
master you need to use kseg1 for now.


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