[PATCH v2] spl: fit: Report fdt error for loading u-boot

[Simon Glass]

Hi,

On Mon, 17 Oct 2022 at 05:53, Su, Bao Cheng <baocheng.su at siemens.com> wrote:
>
> Hi Simon,
>

+Tom Rini for guidance

> On Sat, 2022-07-30 at 19:27 -0600, Simon Glass wrote:
> > Hi Bao Cheng,
> >
> > On Sat, 30 Jul 2022 at 03:05, Su, Bao Cheng <baocheng.su at siemens.com> wrote:
> > >
> > > Commit 71551055cbdb ("spl: fit: Load devicetree when a Linux payload is
> > > found") made a change to not report the spl_fit_append_fdt error at all
> > > if next-stage image is u-boot.
> > >
> > > However for u-boot image without CONFIG_OF_EMBED, the error should be
> > > reported to uplevel caller. Otherwise, uplevel caller would think the
> > > fdt is already loaded which is obviously not true.
> > >
> > > Signed-off-by: Baocheng Su <baocheng.su at siemens.com>
> > > ---
> > >
> > > Changes in v2:
> > > - Fix the wrong wrapping
> > >
> > >  common/spl/spl_fit.c | 8 ++++++--
> > >  1 file changed, 6 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/common/spl/spl_fit.c b/common/spl/spl_fit.c
> > > index a35be52965..00404935cb 100644
> > > --- a/common/spl/spl_fit.c
> > > +++ b/common/spl/spl_fit.c
> > > @@ -770,8 +770,12 @@ int spl_load_simple_fit(struct spl_image_info *spl_image,
> > >          */
> > >         if (os_takes_devicetree(spl_image->os)) {
> > >                 ret = spl_fit_append_fdt(spl_image, info, sector, &ctx);
> > > -               if (ret < 0 && spl_image->os != IH_OS_U_BOOT)
> > > -                       return ret;
> > > +               if (ret < 0) {
> > > +                       if (spl_image->os != IH_OS_U_BOOT)
> > > +                               return ret;
> > > +                       else if (!IS_ENABLED(CONFIG_OF_EMBED))
> > > +                               return ret;
> >
> > This is a pretty unpleasant condition. I think we would be better to
> > report the error and let the caller figure it out.
> >
> > There are no tests associated with this, so it is hard to know what is
> > actually going on.
> >
> > If we must have this workaround, I suggest adding a Kconfig so boards
> > that need it can turn it on, and other boards can use normal
> > operation, which is to report errors.
> >
>
> Since there is no particular error code stands for such kind of
> scenario, it would be hard for the caller to determine which step has
> the problem.
>
> Or below code is more clear?
>
>         if (os_takes_devicetree(spl_image->os)) {
>                 ret = spl_fit_append_fdt(spl_image, info, sector, &ctx);
> -               if (ret < 0 && spl_image->os != IH_OS_U_BOOT)
> -                       return ret;
> +               if (ret < 0
> +                    && (spl_image->os != IH_OS_U_BOOT
> +                      || !IS_ENABLED(CONFIG_OF_EMBED)))
> +                               return ret;
>         }
>
> Actually there is already the `CONFIG_OF_EMBED` to tell them apart, see
> the previous logic before commit 71551055cbdb:
>
>          * Booting a next-stage U-Boot may require us to append the FDT.
>          * We allow this to fail, as the U-Boot image might embed its
> FDT.
>          */
> -       if (spl_image->os == IH_OS_U_BOOT) {
> +       if (os_takes_devicetree(spl_image->os)) {
>                 ret = spl_fit_append_fdt(spl_image, info, sector, &ctx);
> -               if (!IS_ENABLED(CONFIG_OF_EMBED) && ret < 0)
> +               if (ret < 0 && spl_image->os != IH_OS_U_BOOT)
>                         return ret;
>         }
>
> So before the commit 71551055cbdb, the normal case would be to report
> the error, but the commit in question changed this to not report the
> error for normal spl to boot u-boot, only reports error for SPL to boot
> kernel, i.e. falcon mode.

We don't (or shouldn't) have boards which use OF_EMBED in mainline, so
that condition doesn't seem to make sense to me.

Perhaps Tom can decode all of this?

Regards,
Simon