405GP external master

405GP external master

[Root User]

This is a little off-topic, but I know there are
plenty of PPC4xx experts lurking around here...

Anyone use an External Bus master to access SDRAM on
the 405GP?  I'm interested in hearing what kind of
sustained bandwidth you were able to achieve, and if
there were any gotchas to be aware of.

Thanks.


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Re: 405GP external master

[Chris Zimman]

On Tue, Feb 18, 2003 at 01:37:19PM -0800, Root User wrote:
> Anyone use an External Bus master to access SDRAM on
> the 405GP?  I'm interested in hearing what kind of
> sustained bandwidth you were able to achieve, and if
> there were any gotchas to be aware of.

There's an app note at IBM about this:

http://www-3.ibm.com/chips/techlib/techlib.nsf/techdocs/B60C93EB27F44B0F87256AAF005E788F/$file/405DMAPerformance02.pdf

--Chris

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rs_timer

[Prakash kanthi]

Hi Folks,

I observed that, even after linux boots and INIT
process starts, rs_timer stays active and causes the
rs_interrupt_single to be called.

I saw a posting on rs_timer on this message board by
mvista, which says
----------
> Once you hit userland, /dev/ttyS0 is opened and
serial I/O is normally interrupt driven. Prior to that
it uses the polled serial console routines in the
driver. Now, the rs_timer() kludge claims to work for
non-interrupt driven I/O but I've never heard of
anybody using it. You should just hook up your
interrupt controller.
----------

If this is true, after INIT process is invoked, why
does the rs_timer function is called? ByTheWay, my
interrupt controller is on.

Thanks,
Prakash


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Re: rs_timer

[Todd Poynor]

Prakash kanthi wrote:
> Hi Folks,
>
> I observed that, even after linux boots and INIT
> process starts, rs_timer stays active and causes the
> rs_interrupt_single to be called.

Depending on your board and the kernel version you're using, this might
be the result of using IRQ 0 for ttyS0 interrupts (as occurs for ppc_405
boards).  The stock kernel from kernel.org does not recognize IRQ 0 as a
valid value, and sets up rs_timer polling instead.  Recent
linuxppc_2_4_devel kernels (and perhaps other ppc kernel trees) are
modified to remove this restriction; see modifications to
drivers/char/serial.c that remove checks for "irq != 0" and such.
MontaVista Linux makes this an optional feature, enabled by defining
SERIAL_IRQ0_VALID.


--
Todd


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ELDK on windows/cygwin

[Prakash kanthi]

Hi Guys,

Does anyone know if ELDK is available for Windows
platform (like with cygwin, etc...)? Did anyone try
using ELDK on windows/cygwin?

Thanks,
Prakash


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Re: ELDK on windows/cygwin

[Wolfgang Denk]

In message <20030227173016.61851.qmail@web41209.mail.yahoo.com> you wrote:
>
> Does anyone know if ELDK is available for Windows

No, it is not.

> platform (like with cygwin, etc...)? Did anyone try
> using ELDK on windows/cygwin?

We had a few customers asking for it, but it would be a major PITA to
port, and we have zero windoze experience (DENX  is  100%  Microsoft-
free  :-)  and  it  is so much easier to use a Linux server (probably
running Samba to act as windoze file server).


Best regards,

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
Certainly there are things in life that money  can't  buy,  but  it's
very funny - Did you ever try buying them without money? - Ogden Nash

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Flash File System

[Prakash kanthi]

Folks,

I have a 32MB Intel Strata flash on my PPC405 based
custom board. I need to create access routines/APIs to
access the flash. I was thinking of creating a Flash
File System and mount it as a device in Linux
environment.

Are there any off the shelf FFS packages available?
Generally, how the flash is used?

I am working with micro-monitor to use its Tiny File
System on flash support and eventually mount into
linux. Did anyone use this combination before?

Any ideas?

Thanks.
Prakash


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Re: Flash File System

[Wolfgang Denk]

In message <20030326070131.88176.qmail@web41202.mail.yahoo.com> you wrote:
>
> I have a 32MB Intel Strata flash on my PPC405 based
> custom board. I need to create access routines/APIs to
> access the flash. I was thinking of creating a Flash
> File System and mount it as a device in Linux
> environment.
>
> Are there any off the shelf FFS packages available?
> Generally, how the flash is used?

Use the MTD layer.

> I am working with micro-monitor to use its Tiny File
> System on flash support and eventually mount into
> linux. Did anyone use this combination before?

I think you cannot do this. AFAIK the TFS code is not available under
a GPL compatible license which prevents it from being linked with the
Linux kernel code.

Best regards,

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
There is is no reason for any individual to have a computer in  their
home.      -- Ken Olsen (President of Digital Equipment Corporation),
              Convention of the World Future Society, in Boston, 1977

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Re: 405GP external master

[Root User]

> There's an app note at IBM about this:
>
> http://www->
3.ibm.com/chips/techlib/techlib.nsf/techdocs/B60C93EB27F44B0F87256AAF005E788F/$file/405DMAPerformance02.pdf
>
> --Chris

This appnote details the timing for DMA transfers, not
external masters.  I'm hoping that external masters
can result in better throughput than DMA.  With DMA,
you are limited to about 35 MB/sec max.  I need about
twice that bandwidth.

The user guide has timing diagrams for burst accesses
on the external bus.  If external masters and 405GP
can perform sustained, back-to-back burst transfers by
an external master, I should be able to hit my
targets.

Question is whether the 405GP can sustain continuous
burst transactions from an external master, or whether
there are other internal limitations which would
prevent me from hitting 70 MB/sec throughput from
SDRAM<->external master.

Thanks.


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