[PATCH] sunxi: fix initial environment loading without MMC
Andre Przywara
andre.przywara at arm.com
Fri Jun 24 03:00:40 CEST 2022
On Tue, 26 Apr 2022 15:25:56 +0100
Andre Przywara <andre.przywara at arm.com> wrote:
Hi Samuel,
> On Sat, 23 Apr 2022 16:01:00 -0500
> Samuel Holland <samuel at sholland.org> wrote:
>
> Hi Samuel,
>
> thanks for having a look and the comments.
>
> > On 4/20/22 7:34 PM, Andre Przywara wrote:
> > > Commit e42dad4168fe ("sunxi: use boot source for determining environment
> > > location") changed our implementation of env_get_location() and enabled
> > > it for every board, even those without MMC support (like the C.H.I.P.
> > > boards). However the default fallback location of ENVL_FAT does not cope
> > > very well without MMC support compiled in, so the board hangs when trying
> > > to initially load the environment.
> > >
> > > Change the default fallback location to be ENVL_FAT only when the FAT
> > > environment support is enabled, and use ENVL_NOWHERE and ENVL_UBI as
> > > alternative fallbacks, when those sources are enabled.
> > >
> > > This fixes U-Boot loading on the C.H.I.P. boards.
> > >
> > > Fixes: e42dad4168fe ("sunxi: use boot source for determining environment location")
> > > Reported-by: Chris Morgan <macroalpha82 at gmail.com>
> > > Signed-off-by: Andre Przywara <andre.przywara at arm.com>
> > > ---
> > > board/sunxi/board.c | 9 ++++++++-
> > > 1 file changed, 8 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/board/sunxi/board.c b/board/sunxi/board.c
> > > index 89324159d55..befb6076ca6 100644
> > > --- a/board/sunxi/board.c
> > > +++ b/board/sunxi/board.c
> > > @@ -132,7 +132,14 @@ void i2c_init_board(void)
> > > */
> > > enum env_location env_get_location(enum env_operation op, int prio)
> > > {
> > > - enum env_location boot_loc = ENVL_FAT;
> > > + enum env_location boot_loc;
> > > +
> > > + if (IS_ENABLED(CONFIG_ENV_IS_NOWHERE))
> > > + boot_loc = ENVL_NOWHERE;
> > > + else if (IS_ENABLED(CONFIG_ENV_IS_IN_FAT))
> > > + boot_loc = ENVL_FAT;
> > > + else if (IS_ENABLED(CONFIG_ENV_IS_IN_UBI))
> > > + boot_loc = ENVL_UBI;
> >
> > This could leave boot_loc uninitialized. And there is still an unconditional use
> > of ENVL_FAT in the BOOT_DEVICE_MMCx case.
>
> Yeah, it's a mess, and there doesn't seem to be a one-fits-all fallback
> value. Returning ENVL_UNKNOWN when prio is 0 definitely hangs, as does
> returning some source without having the corresponding driver compiled in,
> so getting this right *and* nice-looking is a bit tricky.
>
> > > gd->env_load_prio = prio;
> >
> > I don't think the hook is supposed to change this variable.
>
> Yeah, don't remember why I initially put that in, I must have copied that
> from somewhere. All I remember is that this code is touchy (as the bug
> report leading to that patch shows), and there are quite some corner cases
> to test.
>
> > I'm still a bit confused on the fallback logic you have in place. Splitting it
> > up into three blocks doesn't help. If the goal is to load the environment from
> > the boot device, while preferring filesystems over raw block devices, I propose
> > the following:
>
> Admittedly this gets messier, I mainly wanted to fix the regression
> quickly, since it already broke the release for the CHIP boards.
> I will have a closer look at your suggestion and check for those corner
> cases, but will probably go with that instead of piling up more cruft on
> my previous code ;-)
So I was about to submit your solution, but this is suffering from the
same old problem: we must not return ENVL_UNKNOWN on the first call.
FEL booting triggers this: it will lead to env_init() returning a
negative error value, which is fatal, as it's part of init_sequence_f[].
I think the proper fix is to treat this case the same as the -ENOENT
case at the end of env_init(), but I don't dare to do this generic
change this late in the cycle.
My plan is to hack-fix this for sunxi, for now (see below), then
propose the generic change for the next cycle. Does this sound OK?
Another solution is to always select ENV_IS_NOWHERE, then return this,
but I don't know if this has more side effects, so is also risky at
this point.
> >
> > diff --git a/board/sunxi/board.c b/board/sunxi/board.c
> > index 427113534b..27508bd306 100644
> > --- a/board/sunxi/board.c
> > +++ b/board/sunxi/board.c
> > @@ -129,26 +129,38 @@
> > * Try to use the environment from the boot source first.
> > * For MMC, this means a FAT partition on the boot device (SD or eMMC).
> > * If the raw MMC environment is also enabled, this is tried next.
> > - * SPI flash falls back to FAT (on SD card).
> > */
> > enum env_location env_get_location(enum env_operation op, int prio)
> > {
> > - enum env_location boot_loc = ENVL_FAT;
> > + if (prio > 1)
> > + return ENVL_UNKNOWN;
> >
> > - gd->env_load_prio = prio;
> > + if (IS_ENABLED(CONFIG_ENV_IS_NOWHERE))
> > + return ENVL_NOWHERE;
> >
> > switch (sunxi_get_boot_device()) {
> > case BOOT_DEVICE_MMC1:
> > case BOOT_DEVICE_MMC2:
> > - boot_loc = ENVL_FAT;
> > + if (prio == 0) {
> > + if (IS_ENABLED(CONFIG_ENV_IS_IN_EXT4))
> > + return ENVL_EXT4;
> > + if (IS_ENABLED(CONFIG_ENV_IS_IN_FAT))
> > + return ENVL_FAT;
> > + }
> > + if (IS_ENABLED(CONFIG_ENV_IS_IN_MMC))
> > + return ENVL_MMC;
> > break;
> > case BOOT_DEVICE_NAND:
> > + if (prio == 0 && IS_ENABLED(CONFIG_ENV_IS_IN_UBI))
> > + return ENVL_UBI;
> > if (IS_ENABLED(CONFIG_ENV_IS_IN_NAND))
> > - boot_loc = ENVL_NAND;
> > + return ENVL_NAND;
> > break;
> > case BOOT_DEVICE_SPI:
> > + if (prio == 0 && IS_ENABLED(CONFIG_ENV_IS_IN_UBI))
> > + return ENVL_UBI;
> > if (IS_ENABLED(CONFIG_ENV_IS_IN_SPI_FLASH))
> > - boot_loc = ENVL_SPI_FLASH;
> > + return ENVL_SPI_FLASH;
> > break;
> > case BOOT_DEVICE_BOARD:
> > break;
> > @@ -156,23 +168,6 @@
> > break;
> > }
> >
> > - /* Always try to access the environment on the boot device first. */
> > - if (prio == 0)
> > - return boot_loc;
> > -
> > - if (prio == 1) {
> > - switch (boot_loc) {
> > - case ENVL_SPI_FLASH:
> > - return ENVL_FAT;
> > - case ENVL_FAT:
> > - if (IS_ENABLED(CONFIG_ENV_IS_IN_MMC))
> > - return ENVL_MMC;
> > - break;
> > - default:
> > - break;
> > - }
> > - }
> > -
+ /*
+ * If we come here for the first call, we *must* return a valid
+ * environment location other than ENVL_UNKNOWN, or the setup sequence
+ * in board_f() will silently hang. This is arguably a bug in
+ * env_init(), but for now pick one environment for which we know for
+ * sure to have a driver for. For all defconfigs this is either FAT
+ * or UBI, or NOWHERE, which is already handled above.
+ */
+ if (prio == 0) {
+ if (IS_ENABLED(CONFIG_ENV_IS_IN_FAT))
+ return ENVL_FAT;
+ if (IS_ENABLED(CONFIG_ENV_IS_IN_UBI))
+ return ENVL_UBI;
+ }
Cheers,
Andre
> > return ENVL_UNKNOWN;
> > }
> >
> >
> > Regards,
> > Samuel
>
>
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