printk/console_init - baud rate setting

Siva Prasad sprasad at bivio.net
Wed Nov 14 13:28:56 EST 2007


Thanks a lot Geert and Benjamin for your response.

Code is indeed calling register_console from three different places 
1) con_init()[name-tty], 
2) serial8250_console_init()[name-ttyS], 
3) early_uart_console_init()[name-uart]. 
Among these, 8250 must be the active one. Also
serial8250_console_write() keeps hitting the BDI2000 break point with
same address and count again and again.

I am getting garbage on the screen. So, I presume this must be some sort
of baud rate issue. Can some one help me out understand how this baud is
set for serial drivers? I want to run at 115200.

Thanks
Siva



-----Original Message-----
From: geert at sonytel.be [mailto:geert at sonytel.be] On Behalf Of Geert
Uytterhoeven
Sent: Tuesday, November 13, 2007 12:17 AM
To: Siva Prasad
Cc: linuxppc-dev at ozlabs.org; linuxppc-embedded at ozlabs.org
Subject: Re: printk/console_init

On Mon, 12 Nov 2007, Siva Prasad wrote:
> I am using 2.6.19 Linux on 8641D based system.
> 
> I am using early printk's and it works fine until console_init() is
> executed. After that it does not, as the early printk's get disabled,
> which is fine. However, I don't see any prints after that at all, that
> are based on regular printk statements. I looked directly into the
> memory at __log_buf and found all the print messages. It is just not
> coming out to the serial port properly.
> 
> It would be great if some one can tell me various parameters that I
need
> to consider changing, to successfully port the serial driver for a new
> board.
> 
> Based on the early printk's, I am getting the following messages...
> 
> Using MPC86xx HPCN machine description
> Total memory = 1024MB; using 2048kB for hash table (at cfe00000)
> Linux version 2.6.19 (sprasad at cider.bivio.net) (gcc version 4.1.1
> 20060525 (Red Hat 4.1.1-1)) #115 SMP Mon Nov 12 18:21:43 PST 2007
> Found legacy serial port 0 for /soc8641 at ff700000/serial at 4500
>   mem=ff704500, taddr=ff704500, irq=1a, clk=1496250, speed=0
> Found MPC86xx PCIE host bridge at 0x00000000ff708000. Firmware bus
> number: 0->254
> Found MPC86xx PCIE host bridge at 0x00000000ff709000. Firmware bus
> number: 0->255
> MPC86xx HPCN board from Freescale Semiconductor
> Zone PFN ranges:
>   DMA             0 ->   196608
>   Normal     196608 ->   196608
>   HighMem    196608 ->   262144
> early_node_map[1] active PFN ranges
>     0:        0 ->   262144
> start_kernel: 8 22000000.
> Built 1 zonelists.  Total pages: 260096
> Kernel command line: console=ttyS0,115200 root=/dev/sda8
                               ^^^^^^^^^^^^
> mpic: Setting up MPIC " MPIC     " version 1.2 at ff740000, max 2 CPUs
> mpic: ISU size: 16, shift: 4, mask: f
> mpic: Initializing for 80 sources
> PID hash table entries: 4096 (order: 12, 16384 bytes)
> time_init: decrementer frequency = 150.000000 MHz
> time_init: processor frequency   = 1496.250000 MHz
> <........ Nothing gets printed after this .......>

Did your serial driver (a) call register_console() (b) using the correct
name?

With kind regards,
 
Geert Uytterhoeven
Software Architect

Sony Network and Software Technology Center Europe
The Corporate Village * Da Vincilaan 7-D1 * B-1935 Zaventem * Belgium
 
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Fax:      +32 (0)2 700 8622	
E-mail:   Geert.Uytterhoeven at sonycom.com	
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