Hello Simon
On 27.01.22 18:33, Simon Glass wrote:
Hi Felix,
On Thu, 27 Jan 2022 at 09:27, Felix Brack fb@ltec.ch wrote:
Hello Simon,
On 27.01.22 16:05, Simon Glass wrote:
Hi Felix,
On Wed, 26 Jan 2022 at 07:02, Felix Brack fb@ltec.ch wrote:
Hello Simon,
I am trying to get the current U-Boot master working on the PDU001 board. This involves the use of an early debug UART.
With commit 0dba4586 (arm: Init the debug UART) the early debug UART on the AM33XX SoC doesn't work anymore.
By looking at the code involved I believe a call to setup_clocks_for_console() implemented in clock_am33xx.c before the call to debug_uart_init() is missing. This is also what happens prior to commit 0dba4586 by a call to early_system_init() which in turn calls setup_early_clocks() which then calls setup_clocks_for_console().
My quick and dirty fix consist of inserting a call in crt0.S to setup_clocks_for_console() just before the call to debug_uart_init() which was added in commit 0dba4586. I have guarded this call with #if/#endif testing for CONFIG_AM33XX. The code sequence in crt0.S now looks like this:
#if defined(CONFIG_DEBUG_UART) && CONFIG_IS_ENABLED(SERIAL) #if defined(CONFIG_AM33XX) bl setup_clocks_for_console #endif bl debug_uart_init #endif
However, from what I understand the crt0.S is for _all_ ARM boards hence it's probably a bad idea polluting it with such #if/#endif tests for different SoCs. What do you think?
If my quick and dirty fix is not that dirty I would be happy to send a patch which would also include the removal of the currently remaining call to debug_uart_init() in am33xx/board.c
Please apologize my narrow view of the matter dealing only with AM33XX SoCs.
Are you able to put that call into board_debug_uart_init() and enable CONFIG_DEBUG_UART_BOARD_INIT ?
Sure I can but there two drawbacks:
- this fixes the problem only for my board, others might remain broken
I suggest you make the function common to all boards that need it.
I will check that. Maybe the board_debug_uart_init() is not the right place then as it is board specific. Probably better to have a AM33XX platform specific function.
Having said that there is still something I don't understand: commit 0dba4586 has added a call to debug_uart_init() in crt0.S but not removed any existing call to debug_uart_init(). Hence this function is called twice. Is this intentional (and if so, why ?) or are the remaining calls some sort of leftovers?
- the now redundant call to setup_early_clocks() in am33xx/board.c remains (at least it does not seem to hurt ;-))
Yes, it is possible to use flags to avoid that, but might not be worth it.
I will prepare a patch with a modified board_debug_uart_init() for the PDU001 board then.
-- Many thanks for your help and kind regards, Felix
Regards, Simon