LPC burst accesses

Kári Davíðsson kari.davidsson at marel.is
Wed Dec 12 21:36:56 EST 2007


Using this configuration of the SCLPC I was able to get burst accesses.

Getting bursts with the SDMA general purpose task (without the SCLPC fifo) is
still a mistery to me. I somehow have the feeling that with the CPU one can only
get bursts if we are capable of executing code out of the bank, which implies 
multiplexed mode of the bank. Multiplexed mode I am not able to do, at least
not at this time.


Kári Davíðsson                   | kari.davidsson at marel.is
Hugbúnaðargerð                   | www.marel.com
Tel: +354 563 8156 Fax: +354 563 8001

-----Original Message-----
From: linuxppc-embedded-bounces+karidav=marel.is at ozlabs.org [mailto:linuxppc-embedded-bounces+karidav=marel.is at ozlabs.org] On Behalf Of WITTROCK
Sent: 11. desember 2007 13:43
To: linuxppc-embedded at ozlabs.org
Subject: Re: LPC burst accesses

I remember doing something like this a while back.  I ended up not implementing it in my project for other reasons, but here is some correspondence I had with Freescale:

The question
I am using the LocalPlus bus and BestComm on a MPC5200B to communicate with an external FPGA.

I am currently using CS2 as the chip select for the FPGA.  If I configure the chip select 2 configuration register for a 16bit address width and 2 byte bus width then all works well (MBAR + 0x0308 = 0x00003500).

I am now trying to configure CS2 to operate in LargeFlash mode with 2 byte bus width and 26bit address (MBAR + 0x0308 = 0x00003D00) in order to support a burst read.  I have configured the Chip Select Burst Control Register (BRE2=1), and ensured that PCI is disabled, however I do not see a burst read performed on the bus.

Before I investigate any further, should it be possible to use the LP in LargeFlash mode together with its assosciated FIFO and BestComm to perform a burst read?

The Reply
Local Plus controller performs burst read from LargeFlash or MostGraphic memory only if an XLB master (CPU) or SCLPC interface initiates burst access.

In the case of CPU, you should enable cache for Local Plus memory.
In the case of SCLPC, you should define BPT=8 in the SCLPC Control Register (MBAR + 0x3C08).

Other configurations doesn't force bursting.

Thank you for your interest in Freescale Semiconductor products and for the opportunity to serve you.
Should you need to contact us with regard to this message, please see the notes below.

I hope its of some use.


View this message in context: http://www.nabble.com/LPC-burst-accesses-tp14270986p14274105.html
Sent from the linuxppc-embedded mailing list archive at Nabble.com.

Linuxppc-embedded mailing list
Linuxppc-embedded at ozlabs.org

More information about the Linuxppc-embedded mailing list