Re: [PATCH 3/6] ARM: i.MX: boot: Rework boot source detection for i.MX7 and i.MX8MQ

[Andrey Smirnov <andrew.smirnov@gmail.com>]

On Mon, Aug 13, 2018 at 12:10 AM Sascha Hauer <s.hauer@pengutronix.de> wrote:
>
> On Fri, Aug 10, 2018 at 12:04:26PM -0700, Andrey Smirnov wrote:
> > For both SoCs data found in SBMR registers reflects only the boot
> > source that was selected via pins of fuses and not the final boot
> > source that ended up being used by MaskROM code. Original i.MX7 boot
> > source detection implementation worked around that fact by having a
> > special code to correctly handle "Manufacturing Mode".
> >
> > MaskROM in i.MX8MQ changed what SoC uses as recovery device and
> > switched it to be USDHC2. It also made recovery device switch always
> > enabled. Since correct actual boot source detection is important to
> > being able to properly boot i.MX8MQ (due to not using DCD to
> > initialize RAM), change the code to handle described exception.
> >
> > Instead of trying to adapt original i.MX7 code with yet another
> > special case if(), change the whole thing to do what U-Boot does on
> > i.MX7 and i.MX8MQ and use "Boot information for software" provided by
> > recent (found in i.MX7 and i.MX8MQ) versions of MaskROM.
> >
> > Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> > ---
> >  arch/arm/mach-imx/boot.c | 97 +++++++++++++---------------------------
> >  1 file changed, 30 insertions(+), 67 deletions(-)
> >
> > diff --git a/arch/arm/mach-imx/boot.c b/arch/arm/mach-imx/boot.c
> > index 45170ab10..f1fc40479 100644
> > --- a/arch/arm/mach-imx/boot.c
> > +++ b/arch/arm/mach-imx/boot.c
> > @@ -28,6 +28,7 @@
> >  #include <mach/imx6-regs.h>
> >  #include <mach/imx7-regs.h>
> >  #include <mach/vf610-regs.h>
> > +#include <mach/imx8mq.h>
> >
> >
> >  static void
> > @@ -424,32 +425,12 @@ void imx6_boot_save_loc(void)
> >       imx_boot_save_loc(imx6_get_boot_source);
> >  }
> >
> > -#define IMX7_SRC_SBMR1       0x58
> > -#define IMX7_SRC_SBMR2       0x70
> > +#define IMX7_BOOT_SW_INFO_POINTER_ADDR               0x000001E8
> > +#define IMX8M_BOOT_SW_INFO_POINTER_ADDR_A0   0x000009e8
> > +#define IMX8M_BOOT_SW_INFO_POINTER_ADDR_B0   0x00000968
>
> Uargh. Whatever they smoke @NXP, I hope it at least makes them feel
> good. We are provided a "Boot information for software" pointer whose
> address depends on the mask ROM version?

AFAIK, yes. What I've been told by NXP folks is: "This could
potentially change with each ROM release update" (this meaning the
location address), so I am assuming this all depends on where linker
would place that global variable next time they recompile the MaskROM
code.

> So to use the information we must first get the mask ROM version which itself is found at varying
> offsets in the mask ROM?

True, although this seems like a genuine screw-up, whereas "NXP's
Moving Boot Info" sounds more like a "works as intended" kind of
scenario.

> Needless to say that my i.MX8MQ reference manual specifies the pointer
> address to 0x1e8 which is obviously copied from the i.MX7 Manual without
> adjusting.

Yeah, I discovered that the hard way. I brought it up to NXP folks and
there's supposed to be a ticket, to fix that discrepancy in the next
revision of the RM, somewhere within their corporate ticket tracking
system.

Thanks,
Andrey Smirnov

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