[PATCH u-boot-marvell 1/2] arm: mvebu: spl: Add option to reset the board on DDR training failure

[Stefan Roese]

On 2/17/22 12:37, Pali Rohár wrote:
> On Thursday 17 February 2022 01:08:48 Marek Behún wrote:
>> From: Marek Behún <marek.behun at nic.cz>
>>
>> Some boards may occacionally fail DDR training. Currently we hang() in
>> this case. Add an option that makes the board do an immediate reset in
>> such a case, so that a new training is tried as soon as possible,
>> instead of hanging and possibly waiting for watchdog to reset the board.
>>
>> Signed-off-by: Marek Behún <marek.behun at nic.cz>
>> Reviewed-by: Stefan Roese <sr at denx.de>
>> ---
>>   arch/arm/mach-mvebu/Kconfig | 9 +++++++++
>>   arch/arm/mach-mvebu/spl.c   | 6 +++++-
>>   2 files changed, 14 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/mach-mvebu/Kconfig b/arch/arm/mach-mvebu/Kconfig
>> index d23cc0c760..ed957be6e1 100644
>> --- a/arch/arm/mach-mvebu/Kconfig
>> +++ b/arch/arm/mach-mvebu/Kconfig
>> @@ -213,6 +213,15 @@ config DDR_LOG_LEVEL
>>   	  At level 3, rovides the windows margin of each DQ as a results of
>>   	  DQS centeralization.
>>   
>> +config DDR_RESET_ON_TRAINING_FAILURE
>> +	bool "Reset the board on DDR training failure instead of hanging"
>> +	depends on ARMADA_38X || ARMADA_XP
>> +	help
>> +	  If DDR training fails in SPL, reset the board instead of hanging.
>> +	  Some boards are known to fail DDR training occasionally and an
>> +	  immediate reset may be preferable to waiting until the board is
>> +	  reset by watchdog (if there even is one).
>> +
>>   config SYS_BOARD
>>   	default "clearfog" if TARGET_CLEARFOG
>>   	default "helios4" if TARGET_HELIOS4
>> diff --git a/arch/arm/mach-mvebu/spl.c b/arch/arm/mach-mvebu/spl.c
>> index 273ecb8bd6..d3c3bdc74d 100644
>> --- a/arch/arm/mach-mvebu/spl.c
>> +++ b/arch/arm/mach-mvebu/spl.c
>> @@ -4,6 +4,7 @@
>>    */
>>   
>>   #include <common.h>
>> +#include <cpu_func.h>
>>   #include <dm.h>
>>   #include <fdtdec.h>
>>   #include <hang.h>
>> @@ -330,7 +331,10 @@ void board_init_f(ulong dummy)
>>   	ret = ddr3_init();
>>   	if (ret) {
>>   		printf("ddr3_init() failed: %d\n", ret);
>> -		hang();
>> +		if (IS_ENABLED(CONFIG_DDR_RESET_ON_TRAINING_FAILURE))
>> +			reset_cpu();
> 
> You should not call reset_cpu() from SPL loaded via UART. This will
> confuse x-modem software. Either return failure to BootROM or hang()
> like it was before.

I see that this might confuse the kwboot / x-modem use-case. But AFAIU,
this is more targeted to the normal use-case, that the board boots from
SPI NOR (etc). And here, a complete re-start could be helpful to at
least get the board up and running after a few retries.

Or am I missing something?

Thanks,
Stefan