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

[Su, Bao Cheng]

Hi Simon,

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.

> Regards,
> Simon