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Re: Request for comments - Redboot load command writing directly toflash
- From: Laurent GONZALEZ <laurent dot gonzalez at silicomp dot fr>
- To: ecos-patches at sources dot redhat dot com, oyvind dot harboe at zylin dot com
- Date: Fri, 11 Jul 2003 11:14:30 +0200
- Subject: Re: Request for comments - Redboot load command writing directly toflash
- Organization: SILICOMP RESEARCH INSTITUTE
- References: <000801c34783$67f12290$73dea8c0@lair>
The AT91R40008 is perfectly able to handle serial line baud rate higher than 38400. I have experienced eb40a at 115200 and even higher baud rate, for application and redboot.
The MCU has no HW fifo, but an integrate DMA like engine. So it is better than HW fifo, because you can size it up to 64K (When memory is available ;)
AFAIK, the HAL serial driver does not use this feature, and I think it is deliberate, to keep the serial simple and reliable for debug. The interrupt driven driver (devs/serial/arm/at91) neither uses it, however this point has already been discuss, and someone has already proposed a patch. Seek the archives.
Using such a hardware, the soft can be very efficient.
On Fri, 11 Jul 2003 10:07:00 +0200
Øyvind Harboe <firstname.lastname@example.org> wrote:
> - I tried to modify the serial port rate on my EB40a to >38400,
> but it didn't work. There may be trouble with any
> baudrate != 38400 on EB40a, but I haven't checked.
> - I'm not quite sure why it works as well as it does :-)
> AFAIK, Redboot does not run with interrupts enabled and if
> Redboot is off flashing a byte, whos servicing the serial port?
> As is, I assume that there is a fairly big HW fifo on my EB40a
> board, and thats why it works as well as it does.
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