cs8900a always returning 0x5555

Hi- I am working on developing cs8900a driver under linux 2.4. The system
configuration is: arm9+linux(kernel 2.4), the cs8900a is working on IO
mode and its bus address is 0x1001_0000, its default IO base is 0x300.
Problem is, cs8900a always returning 0x5555 when I read like this:

..

static unsigned int virt_base;
		
if(check_mem_region(0x10010000, 0x1000)){
	printk(KERN_INFO "CS8900A: memory already in use\n");
} else 
	request_mem_region(0x10010000, 0x1000, "CS8900A");

virt_base = (unsigned int)ioremap(0x10010000, 0x1000); // 4k bytes

//read the product id
writew(0x0000, virt_base+0x30a);
printk(KERN_INFO "CS8900A :  0x%lx\n", readw(iov6+0x30c));

...

I ' m now struggling with this problem for weeks and would really
apreciate any help on this.

On Mon, 22 May 2006 01:05:02 -0400, "Aimingoo" <aimingoo@gmail.com>
wrote:

>Hi- I am working on developing cs8900a driver under linux 2.4. The system
>configuration is: arm9+linux(kernel 2.4), the cs8900a is working on IO
>mode and its bus address is 0x1001_0000, its default IO base is 0x300.
>Problem is, cs8900a always returning 0x5555 when I read like this:

[snip]

>I ' m now struggling with this problem for weeks and would really
>apreciate any help on this.

But you were most likely not searching the comp.arch.embedded archives
in google cause otherwise you would have stumbled over my thread about
the exactly same problem weeks before :-) :

http://groups.google.ch/group/comp.arch.embedded/browse_frm/thread/f0f3de4465c7dc8d/80ea9027f7b0c89a?tvc=1&q=cs8900a+author%3AMarkus+author%3AZingg&hl=de#80ea9027f7b0c89a

In short, I did not had enough wait states and hence the controller
did not had enough time to set the propper value on the port.

Since I also got back 0x5555 and since your controller (arm9) is a
pretty fast one I'm somehow confident that your design suffers from
the same problem I was facing.

HTH

Markus

Hi,thanks your time first!
I have accessed the signature of cs8900a correctly via emluator. But I
can't accessed it under linux driver, so I think it may be something wrong
with function 'ioremap' or other mistake, would you give me some advise on
map physical address of cs8900a to virtual address?

Thanks again!

Hi,thanks your time first!
I have accessed the signature of cs8900a correctly via emluator. But I
can't accessed it under linux driver, so I think it may be something wrong
with function 'ioremap' or other mistake, would you give me some advise on
map physical address of cs8900a to virtual address?

Thanks again!

>Hi,thanks your time first!
>I have accessed the signature of cs8900a correctly via emluator. But I
>can't accessed it under linux driver, so I think it may be something wrong
>with function 'ioremap' or other mistake, would you give me some advise on
>map physical address of cs8900a to virtual address?
>
>Thanks again!

I'm sorry, I did not currently use linux. However due to the fact that
you see the same pattern (0x5555) I still think it's a timeing issue.
The emulator you refer to could be just that tad bit slower with it's
operation on the bus to make the difference. Otherwise you might ask
in a new thread here about the ioremap function so as other might jump
in but again, I'd say it's the timeing. The cs8900a is horribly slow
on it's digital interface. I'm not going to use it in a new design for
this very reason. Apart from this it's a nice chip though.

HTH

Markus

Aimingoo wrote:
> 
> I have accessed the signature of cs8900a correctly via emluator.
> But I can't accessed it under linux driver, so I think it may be
> something wrong with function 'ioremap' or other mistake, would
> you give me some advise on map physical address of cs8900a to
> virtual address?

In this particular case it doesn't matter too much, but in general
on usenet you should realize that readers may very well not have
convenient access to previous articles in a thread.  That means
that your reply articles should include adequate context, so that
they stand by themselves.  Google is NOT usenet, it is only a very
poor interface to the real usenet system.  To include proper
context when using google, see my sig. below.  Please be sure to
read the referenced URLs.

-- 
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 the broken "Reply" link at the bottom of the article.  Click on 
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