[PATCH v2 u-boot] mmc: spl: Make partition choice in default_spl_mmc_emmc_boot_partition() more explicit
Pali Rohár
pali at kernel.org
Fri Jul 7 19:56:56 CEST 2023
On Friday 07 July 2023 13:10:19 Tom Rini wrote:
> On Fri, Jul 07, 2023 at 07:05:45PM +0200, Pali Rohár wrote:
> > On Friday 07 July 2023 12:54:58 Tom Rini wrote:
> > > On Fri, Jul 07, 2023 at 06:46:39PM +0200, Pali Rohár wrote:
> > > > On Thursday 06 July 2023 13:52:14 Tom Rini wrote:
> > > > > On Thu, Jul 06, 2023 at 07:49:18PM +0200, Pali Rohár wrote:
> > > > > > On Thursday 06 July 2023 13:42:18 Tom Rini wrote:
> > > > > > > On Thu, Jul 06, 2023 at 07:35:02PM +0200, Pali Rohár wrote:
> > > > > > > > To make eMMC partition choosing in default_spl_mmc_emmc_boot_partition()
> > > > > > > > function better understandable, rewrite it via explicit switch-case code
> > > > > > > > pattern.
> > > > > > > >
> > > > > > > > Also add a warning when eMMC EXT_CSD[179] register is configured by user to
> > > > > > > > value which is not suitable for eMMC booting and SPL do not know how to
> > > > > > > > interpret it.
> > > > > > > >
> > > > > > > > Note that when booting from eMMC device via EXT_CSD[179] register is
> > > > > > > > explicitly disabled then SPL still loads and boots from this eMMC device
> > > > > > > > from User Area partition. This behavior was not changed in this commit and
> > > > > > > > should be revisited in the future.
> > > > > > > >
> > > > > > > > Signed-off-by: Pali Rohár <pali at kernel.org>
> > > > > > > > ---
> > > > > > > > Changes in v2:
> > > > > > > > * Disable showing warning on sama5d2_xplained due to size restrictions
> > > > > > > > ---
> > > > > > > > This patch depends on another patch:
> > > > > > > > mmc: spl: Add comments for default_spl_mmc_emmc_boot_partition()
> > > > > > > > https://patchwork.ozlabs.org/project/uboot/patch/20230404202805.8523-1-pali@kernel.org/
> > > > > > > > ---
> > > > > > > > common/spl/Kconfig | 7 +++++++
> > > > > > > > common/spl/spl_mmc.c | 46 ++++++++++++++++++++++++++++++++++++--------
> > > > > > > > 2 files changed, 45 insertions(+), 8 deletions(-)
> > > > > > > >
> > > > > > > > diff --git a/common/spl/Kconfig b/common/spl/Kconfig
> > > > > > > > index 865571d4579c..0574d22b3b25 100644
> > > > > > > > --- a/common/spl/Kconfig
> > > > > > > > +++ b/common/spl/Kconfig
> > > > > > > > @@ -855,6 +855,13 @@ config SPL_MMC_WRITE
> > > > > > > > help
> > > > > > > > Enable write access to MMC and SD Cards in SPL
> > > > > > > >
> > > > > > > > +config SPL_MMC_WARNINGS
> > > > > > > > + bool "Print MMC warnings"
> > > > > > > > + depends on SPL_MMC
> > > > > > > > + default y if !TARGET_SAMA5D2_XPLAINED
> > > > > > > > + help
> > > > > > > > + Print SPL MMC warnings. You can disable this option to reduce SPL size.
> > > > > > > > +
> > > > > > > >
> > > > > > > > config SPL_MPC8XXX_INIT_DDR
> > > > > > > > bool "Support MPC8XXX DDR init"
> > > > > > > > diff --git a/common/spl/spl_mmc.c b/common/spl/spl_mmc.c
> > > > > > > > index f7a42a11477d..ec424ceded0e 100644
> > > > > > > > --- a/common/spl/spl_mmc.c
> > > > > > > > +++ b/common/spl/spl_mmc.c
> > > > > > > > @@ -408,15 +408,45 @@ int default_spl_mmc_emmc_boot_partition(struct mmc *mmc)
> > > > > > > > *
> > > > > > > > * Note: See difference between EXT_CSD_EXTRACT_PARTITION_ACCESS
> > > > > > > > * and EXT_CSD_EXTRACT_BOOT_PART, specially about User area value.
> > > > > > > > - *
> > > > > > > > - * FIXME: When booting from this eMMC device is explicitly
> > > > > > > > - * disabled then we use User area for booting. This is incorrect.
> > > > > > > > - * Probably we should skip this eMMC device and select the next
> > > > > > > > - * one for booting. Or at least throw warning about this fallback.
> > > > > > > > */
> > > > > > > > - part = EXT_CSD_EXTRACT_BOOT_PART(mmc->part_config);
> > > > > > > > - if (part == 7)
> > > > > > > > - part = 0;
> > > > > > > > + if (mmc->part_config == MMCPART_NOAVAILABLE)
> > > > > > > > + part = 0; /* If partitions are not supported then we have only User Area partition */
> > > > > > > > + else {
> > > > > > > > + switch(EXT_CSD_EXTRACT_BOOT_PART(mmc->part_config)) {
> > > > > > > > + case 0: /* Booting from this eMMC device is disabled */
> > > > > > > > +#ifdef CONFIG_SPL_LIBCOMMON_SUPPORT
> > > > > > > > +#ifdef CONFIG_SPL_MMC_WARNINGS
> > > > > > > > + puts("spl: WARNING: Booting from this eMMC device is disabled in EXT_CSD[179] register\n");
> > > > > > > > + puts("spl: WARNING: Continuing anyway and selecting User Area partition for booting\n");
> > > > > > > > +#else
> > > > > > > > + puts("spl: mmc: fallback to user area\n");
> > > > > > > > +#endif
> > > > > > > > +#endif
> > > > > > > > + /* FIXME: This is incorrect and probably we should select next eMMC device for booting */
> > > > > > > > + part = 0;
> > > > > > > > + break;
> > > > > > > > + case 1: /* Boot partition 1 is used for booting */
> > > > > > > > + part = 1;
> > > > > > > > + break;
> > > > > > > > + case 2: /* Boot partition 2 is used for booting */
> > > > > > > > + part = 2;
> > > > > > > > + break;
> > > > > > > > + case 7: /* User area is used for booting */
> > > > > > > > + part = 0;
> > > > > > > > + break;
> > > > > > > > + default: /* Other values are reserved */
> > > > > > > > +#ifdef CONFIG_SPL_LIBCOMMON_SUPPORT
> > > > > > > > +#ifdef CONFIG_SPL_MMC_WARNINGS
> > > > > > > > + puts("spl: WARNING: EXT_CSD[179] register is configured to boot from Reserved value\n");
> > > > > > > > + puts("spl: WARNING: Selecting User Area partition for booting\n");
> > > > > > > > +#else
> > > > > > > > + puts("spl: mmc: fallback to user area\n");
> > > > > > > > +#endif
> > > > > > > > +#endif
> > > > > > > > + part = 0;
> > > > > > > > + break;
> > > > > > > > + }
> > > > > > > > + }
> > > > > > > > #endif
> > > > > > >
> > > > > > > Please just use debug() for these messages.
> > > > > >
> > > > > > All other error/warning messages in this file are printed via puts().
> > > > > > So I'm just following the current style (and I'm really not going to
> > > > > > change all occurrences in this patch).
> > > > >
> > > > > Except for the messages in that file which use debug() they use puts(),
> > > > > yes. Since none of these are fatal messages (you're falling through)
> > > > > please switch them to debug() rather than introduce a new CONFIG symbol,
> > > > > so that if someone is bringing up a platform where this is a problem
> > > > > they'll be able to debug it, but the general case does not increase
> > > > > the binary size of most platforms. I'm not asking you to change anything
> > > > > existing in the file, only what you're adding.
> > > >
> > > > We should at those two places fail. But I do not want to break existing
> > > > improperly configured setups, so warning a good way to show people that
> > > > they have something misconfigured. Later in future we switch warnings to
> > > > fatal errors. But if we do not show anything at these points, nobody
> > > > would figure out that has improper setup configuration. debug() is IIRC
> > > > not shown by default.
> > >
> > > Ah, so the plan is they should be fatal, and there's a way to fix the
> > > configuration?
> >
> > Yes, EXT_CSD[179] is configurable register, you can change boot
> > partition bits (those are non-volatile) via your favorite emmc config
> > tool. U-Boot has also tool "mmc partconf" which can do that. But you
> > first need to be able enter into u-boot console and also you need to
> > enable this tool your board config file.
> >
> > > Lets just panic() them now, instead. I really really do
> > > not want to grow every SPL+MMC using board (which is a lot of them) by
> > > several hundred bytes of strings. Lets catch the mis-configuration,
> > > merge it in early in the cycle (right now for v2023.10 for example,
> > > especially since the MMC custodian is promising to review things and get
> > > a PR out ASAP), and see what falls out. A panic() and a big comment
> > > explaining things should suffice.
> >
> > Ok, I can change "reserved values" to panic().
> >
> > About "booting is disabled" - I do not think that panic is correct here.
> > See inline comments in code. Rather do the correct thing - skip emmc and
> > let SPL to boot from next source. But some message needs to be printed
> > here why emmc was skipped....
>
> How verbose all of this needs to be depends on who is likely to
> encounter this type of problem. Are we talking about systems in the wild
> today that are misconfigured, or are we talking about problems that will
> arise as part of bringing up a new design and if you don't do X
> correctly then Y will happen oddly/wrongly?
>
> --
> Tom
I have no idea. We already seen that not all people understood how it
works. And also people are always creative in inventing hacks. So
this is mainly for existing systems.
For future in mmc area I have just cleanup patches which should not
result in code change or in behavior change.
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