Hi Vasili,
On 29 April 2015 at 10:57, Vasili Galka vvv444@gmail.com wrote:
Hi Tom,
I’m working on rebasing an old U-Boot branch for our company’s AM335x based board upon the current U-Boot release (v2015.04). Our branch was initially based on the v2013.10 release (the ti/am335x/ board was taken as reference).
After making all the code compile, I discovered there was a change in the U-Boot initialization sequence, introduced by commit a6b541b09022acb6f7c2754100ae26bd44eed1d9, that prevents our code from working:
Prior to the above mentioned commit, the console serial port was initialized at a very early stage in the armv7/am335x/board.c:s_init() function (calling preloader_console_init()). Roughly saying, it was the first thing done by the SPL code. This made quite much sense, as it enabled all the code afterwards to output status/debugging info to the console. Moving the preloader_console_init() call to spl_board_init() caused it to be run at a very "late" stage (as part of the board_init_r() function). AFAIU, now all the code that runs till then has no ability for any console output. For example, in our particular case, the DDR configuration code (in sdram_init()) reads the DDR type from an I2C EEPROM. Obviously, if something goes wrong in this process, we would like to report it to the console.
I understand there was a good reason for the mentioned commit (the GD), however, as you see, we have also lost some important functionality with it. I would appreciate your advice on how to solve it.
It would certainly be very useful and it would be great if we could printf() from as soon as we have a stack (and perhaps printch() even earlier). I think it can be done, but I have not put in the time to figure it out.
You could take a look at CONFIG_DEBUG_UART which at least allows primitive UART access before gd is set up. I wonder if we could do something like change printf() /purchatr() to use this when gd is NULL?
Regards, Simon