[U-Boot] [PATCH] arm: socfpga: dm: Fix DM initialization failure after warm reset

[Simon Glass]

Hi Marek,

On 29 August 2015 at 09:45, Marek Vasut <marex at denx.de> wrote:
> On Saturday, August 29, 2015 at 04:49:37 PM, Simon Glass wrote:
>> Hi Marek,
>>
>> On 29 August 2015 at 08:46, Marek Vasut <marex at denx.de> wrote:
>> > On Saturday, August 29, 2015 at 04:39:43 PM, Simon Glass wrote:
>> >> Hi Marek,
>> >>
>> >> On 29 August 2015 at 01:56, Marek Vasut <marex at denx.de> wrote:
>> >> > On Saturday, August 29, 2015 at 01:21:31 AM, Simon Glass wrote:
>> >> > > Hi,
>> >> > >
>> >> > > On 28 August 2015 at 02:41, Jian Luo <Jian.Luo4 at boschrexroth.de> wrote:
>> >> > > > gd->dm_root is not cleared in SPL after warm reset.
>> >> > > > This might cause DM initilazation failure.
>> >> > > >
>> >> > > > Signed-off-by: Jian Luo <jian.luo4 at boschrexroth.de>
>> >> > > > ---
>> >> > > >
>> >> > > >  arch/arm/mach-socfpga/spl.c | 6 ++++++
>> >> > > >  1 file changed, 6 insertions(+)
>> >> > > >
>> >> > > > diff --git a/arch/arm/mach-socfpga/spl.c
>> >> > > > b/arch/arm/mach-socfpga/spl.c index 13ec24b..59fe1f2 100644
>> >> > > > --- a/arch/arm/mach-socfpga/spl.c
>> >> > > > +++ b/arch/arm/mach-socfpga/spl.c
>> >> > > > @@ -181,5 +181,11 @@ void board_init_f(ulong dummy)
>> >> > > >
>> >> > > >         /* Configure simple malloc base pointer into RAM. */
>> >> > > >         gd->malloc_base = CONFIG_SYS_TEXT_BASE + (1024 * 1024);
>> >> > > >
>> >> > > > +       /*
>> >> > > > +        * gd->dm_root might contain non-zero value after warm
>> >> > > > reset. +        * Clear it to avoid dm_init error
>> >> > > > +        */
>> >> > > > +       gd->dm_root = NULL;
>> >> > > > +
>> >> > > >
>> >> > > >         board_init_r(NULL, 0);
>> >> > > >
>> >> > > >  }
>> >> > > >
>> >> > > > --
>> >> > > > 1.9.1
>> >> > >
>> >> > > This does not look like the root cause to me. global_data is zeroed
>> >> > > by crt0.S if CONFIG_SPL_FRAMEWORK is set, which it seems to be for
>> >> > > socfpga.
>> >> > >
>> >> > > What boot path does 'warm reset' take?
>> >> >
>> >> > Warm reset resets the CPU core(s) and jumps to 0x0 in SRAM (without
>> >> > re-reading anything from the boot media).
>> >>
>> >> Does that mean it skips crt0.S? How come global_data is not zeroed
>> >> there?
>> >
>> > No, it does not mean it skips crt0.S . After the warm reset, the bootrom
>> > jumps onto the reset vector, so crt0.S (_main) must be executed.
>>
>> Then I don't understand the need for this patch.
>
> Apparently, the gd->dm_root is set to a non-NULL address for some (unknown)
> reason. I don't quite understand this myself.
>
> The only possibility which can lead to gd->dm_root being set to non-NULL address
> is that crt0.S _main is not executed, is that correct ?

I think so, unless driver model was already inited by a call to
spl_init(). But I don't see where your board might do that.

Regards,
Simon