virtex uImage and serial ports

[Joshua Lamorie]

Gidday John,

Thanks for the pointer.  I think I have already gone through every possible page on the wiki, without finding my answer.  There are some great pointers however, such as http://xilinx.wikidot.com/debugging-kernel-boot-problems.  

As far as I can tell, if I do 'make uImage', there is no code built into vmlinux that will parse the device tree and set up the serial ports (at least as far as I can see with objdump -S).  When it boots, there is no console output and __log_buf doesn't show any serial ports detected during the initialization of the serial driver.

Which leads to my question, how does the 8250 serial driver get the information about the attached serial ports from the dtb?  Which part of the code parses the dtb, finds the "ns16550" and updates/builds the platform_device information for the 8250 serial port driver?

Joshua

On Tuesday, 30 December, 2008 13:16, "John Linn" <John.Linn at xilinx.com> said:

> Hi Joshua,
> 
> Have you looked at our wiki site at http://xilinx.wikidot.com as we
> quite a bit of information there.
> 
> The ML405 board is a V2Pro chip so it should be pretty close to what you
> want using the default kernel config for virtex4.
> 
> I haven't tested the console at 115,200 as I use it at 9600.  Shouldn't
> be a problem, but may not hurt to stay at 9600 to get it working.
> 
> There are pages on the wiki about using u-boot with the kernel also as
> it sounds like that's what you're doing.
> 
> Thanks,
> John
> 
> 
>> -----Original Message-----
>> From: linuxppc-embedded-bounces+john.linn=xilinx.com at ozlabs.org
> [mailto:linuxppc-embedded-
>> bounces+john.linn=xilinx.com at ozlabs.org] On Behalf Of Joshua Lamorie
>> Sent: Wednesday, December 24, 2008 3:48 PM
>> To: linuxppc-embedded at ozlabs.org
>> Subject: virtex uImage and serial ports
>>
>> Gidday there,
>>
>> I am trying to get 2.6.27(ish) running on my custom Virtex-II Pro
> platform (I call it Q5).  I already
>> have many years of running 2.4.26 and booting from u-boot.
>>
>> The problem is getting the console running.  I have a device tree blob
> built and loaded into memory,
>> and by peeking at __log_buf I can see that it is reading this okay
> (i.e. it is correctly finding my
>> interrupt controller).  However, by the time it goes to mount the
> ramdisk as root, it complains that
>> there is no console.
>>
>> I'm fairly certain /chosen has stdout pointing to the correct UART,
> and the console arguments are
>> ttyS0,115200.
>>
>> In looking through the code however, I cannot figure out how the
> uImage code actually initializes the
>> serial-ports for the XILINX_VIRTEX_GENERIC_BOARD.  As I understand it,
> the only place where
>> serial_console_init is called, is within platform_init, and this isn't
> called for uImage.
>>
>> So, three questions.
>>
>> 1) How is the serial driver supposed to know where the platforms
> serial ports are?
>>
>> 2) If I wanted to scrap u-boot and just copy kernel/ramdisk/dtb to
> memory, which kernel make target
>> should I use?  dtbImage, simpleImage?
>>
>> 3) What is the best, most modern image to build that should be used by
> u-boot?
>>
>> Thanks in advance
>>
>> Joshua
>>
>> p.s. I've been trying with kernel.org mainline, xilinx git and denx
> ELDK xenomai (2.6.24).  U-boot is
>> built from latest git source.  DTS file built from XPS 9.1i with
> latest service packs, and turned
>> into DTB with latest dtc source from git.
>>
>>
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