Re: [U-Boot] [PATCH 0/2] fix issue with mmc partition management

2014-09-11 Thread Tom Rini 
On Tue, Sep 02, 2014 at 06:31:21PM -0500, Peter A. Bigot wrote:

 This series aims at addressing an issue discovered with SPL mode when
 the MMC device being used lacks an environment partition.
 http://www.mail-archive.com/meta-ti@yoctoproject.org/msg04320.html
 includes details on the original failure with this diagnosis:
 
   This is a bug in handling mmc_switch_part: what's happening is that
   the code reconfigures the mmc device to look at the partition on which
   the environment is to be found, but fails to restore it to reflect the
   state of the whole device. I.e., the mmc capacity and lba are zero in
   my case (I have no partition 2 on the uSD card), but mmc_switch_part()
   returns -ENODEV on the attempt to switch back in fini_mmc_for_env()
   without also resetting the capacity to what the rest of the system
   expects.

1/2 has been superseded and there's some questions about 2/2.  I'm going
to take 2/2 as it fixes a real problem.  But Stephen brings up some good
questions that do need to be answered.  The first thing is that SPL
today assumes that it only has one MMC device registered with the
subsystem, not 2.  This may be reworkable (and maybe not have a big size
change) but it's a bit late in this release cycle for that.  So what
this means is that on some hardware like say Beaglebone Black we either
have an SD card (which lacks physical partitions) or we have an eMMC
which means the 2 boot partitions and the user partition.

The next part of the problem is that we have some cases where we say
environment is on eMMC, in one of the boot partitions and we say SPL
needs to look at the environment.  This situation works fine when we
boot from eMMC.  Things fail when we use this same binary to boot from
SD card.  We don't have env and somewhere along the line what fails is
that we tried to switch physical partition, noticed a failure, tried to
correct said failure but instead end up with our internal representation
of the SD/MMC device being invalid.  Peter's patch 2/2 corrects this so
that when we hit a failure it goes and re-sets that representation.

But the next question is wait, why did it get set _wrong_ to start
with?.  I'm not sure actually.  The fini_mmc_for_env call isn't making
us be restored to what the physical partition was before, if that's what
it was intended to do, it's making sure that we're still on the env
partition.  Which I'm not sure why it needs to do since we've already
read a copy into memory at this point.

-- 
Tom


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[U-Boot] [PATCH 0/2] fix issue with mmc partition management

2014-09-02 Thread Peter A. Bigot 
This series aims at addressing an issue discovered with SPL mode when
the MMC device being used lacks an environment partition.
http://www.mail-archive.com/meta-ti@yoctoproject.org/msg04320.html
includes details on the original failure with this diagnosis:

  This is a bug in handling mmc_switch_part: what's happening is that
  the code reconfigures the mmc device to look at the partition on which
  the environment is to be found, but fails to restore it to reflect the
  state of the whole device. I.e., the mmc capacity and lba are zero in
  my case (I have no partition 2 on the uSD card), but mmc_switch_part()
  returns -ENODEV on the attempt to switch back in fini_mmc_for_env()
  without also resetting the capacity to what the rest of the system
  expects.

The first fixes a mistaken assumption about how mmc_switch_part()
behaves.  (Personally, I think mmc_switch_part() should have recorded
the new partition in the device structure, but that's an behavioral
change that I'm not going to introduce.)

The second fixes the underlying problem, which was the failure to
restore the capacity configuration to the whole device after interacting
with the environment.

FWIW: The second patch is relevant to 2014.07; the first is not.

Peter A. Bigot (2):
  env_mmc: remove condition on call to mmc_switch_part
  mmc: restore capacity when switching to partition 0

 common/env_mmc.c  | 11 ---
 drivers/mmc/mmc.c | 11 ---
 2 files changed, 12 insertions(+), 10 deletions(-)

-- 
1.8.5.5

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