[PATCH u-boot-mvebu 10/10] arm: mvebu: turris_omnia: Support old DDR3 training, selectable via env var

[Marek Behún]

On Mon, 6 May 2024 12:03:55 +0200
Stefan Roese <sr at denx.de> wrote:

> Hi Marek,
> 
> On 4/15/24 18:30, Marek Behún wrote:
> > Support old DDR3 training code on Turris Omnia, selectable by U-Boot
> > enviroment variable.
> > 
> > Users experiencing DDR3 initialization failures or random crashes of the
> > operating system due to incorrect DDR3 configuration can select the old
> > DDR3 training implementation to fix those issues by setting the
> > environment variable
> >    env set omnia_ddr3_training old
> >    env save
> > 
> > Signed-off-by: Marek Behún <kabel at kernel.org>
> > ---
> >   arch/arm/mach-mvebu/Kconfig                   |  1 +
> >   board/CZ.NIC/turris_omnia/Makefile            |  1 +
> >   board/CZ.NIC/turris_omnia/old_ddr3_training.c | 79 +++++++++++++++++++
> >   board/CZ.NIC/turris_omnia/turris_omnia.c      |  2 +-
> >   4 files changed, 82 insertions(+), 1 deletion(-)
> >   create mode 100644 board/CZ.NIC/turris_omnia/old_ddr3_training.c  
> 
> For turris_omnia_defconfig, this is dropped when compiled:
> 
> drivers/ddr/marvell/a38x/old/ddr3_debug.c:776:12: warning: 
> 'ddr3_tip_access_atr' declared 'static' but never defined 
> [-Wunused-function]
>    776 | static int ddr3_tip_access_atr(u32 dev_num, u32 flag_id, u32 
> value, u32 **ptr);
>        |            ^~~~~~~~~~~~~~~~~~~

And it also seems that there is still something wrong with this
old DDR training code port. Some boards still experience random bugs
with this, but not with the U-Boot from 2015. :-(