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

[Pali Rohár]

On Thursday 17 February 2022 12:42:58 Stefan Roese wrote:
> 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).

But kwb image is universal for both UART and SPI booting. So it target
both use cases.

> And here, a complete re-start could be helpful to at
> least get the board up and running after a few retries.

Of course, for SPI boot source it is required.

> Or am I missing something?

Just reset_cpu() call should be skipped when SPL is loaded via UART.

> Thanks,
> Stefan