On Thu, 13 Apr 2023 23:10:56 +0200 Pali Rohár <p...@kernel.org> wrote:
> Mapping between bootpart taken from EXT_CSD_EXTRACT_BOOT_PART() and > Partition Access bits used by the mmc_switch_part() function may be quite > misleading. So add extended comment describing why in sunxi case is this > mapping just a simple identity. Because in generic case this mapping > requires non-trivial mapping table. Ah, indeed, many thanks for clearing this up! I missed the subtleties of bootpart meaning slightly different things between EXT_CSD_EXTRACT_BOOT_PART and mmc_switch_part(). It looks like we were quite lucky as we only care about 1 and 2 here! > Signed-off-by: Pali Rohár <p...@kernel.org> Acked-by: Andre Przywara <andre.przyw...@arm.com> Queued for sunxi/master. Cheers, Andre > --- > arch/arm/mach-sunxi/board.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/arch/arm/mach-sunxi/board.c b/arch/arm/mach-sunxi/board.c > index 391a65a5495f..73519f6262ec 100644 > --- a/arch/arm/mach-sunxi/board.c > +++ b/arch/arm/mach-sunxi/board.c > @@ -381,7 +381,17 @@ static bool sunxi_valid_emmc_boot(struct mmc *mmc) > (mmc->ext_csd[EXT_CSD_BOOT_BUS_WIDTH] & 0x1b) != 0x09) > return false; > > - /* Partition 0 is the user data partition, bootpart must be 1 or 2. */ > + /* > + * bootpart == 0 means that eMMC booting is disabled. > + * bootpart == 1 or 2 means to boot from Boot Partition 1 or 2. > + * bootpart == 7 means to boot from User Area. > + * Other bootpart values are reserved. > + * mmc_switch_part() takes partition access value which is: > + * 0 for User Area; 1-2 for Boot Partition 1-2; 3 for RPMB; 4-7 for GP > 1-4. > + * We allow booting only from Boot Partition 1 or 2 so > + * bootpart mapping between EXT_CSD_EXTRACT_BOOT_PART() > + * and mmc_switch_part() is straightforward identity. > + */ > if (bootpart != 1 && bootpart != 2) > return false; >
