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SAMA5 NAND: Only CS3 can have NAND

This commit is contained in:
Gregory Nutt 2013-12-03 06:59:22 -06:00
parent 46287d55d0
commit 5a1350b475
1 changed files with 51 additions and 10 deletions
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61
configs/sama5d3x-ek/README.txt
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@ -1352,6 +1352,9 @@ SDRAM Support
NAND Support
============
NAND Support
------------
NAND Support can be added to the NSH configuration by modifying the
NuttX configuration file as follows:
@ -1393,19 +1396,25 @@ NAND Support
Other file systems are not recommended because only NXFFS can handle
bad blocks and only NXFFS performs wear-leveling.
NOTE: NXFFS is very slow. The first time that you start the system,
be prepared for a long wait; NXFFS will need to format the NAND
NOTE: NXFFS can be very slow. The first time that you start the
system, be prepared for a wait; NXFFS will need to format the NAND
volume. I have lots of debug on so I don't yet know what the
optimized wait would be. But with debug ON, software ECC, and no
DMA the wait is in many tens of minutes, even hours if many debug
options are enabled.
optimized wait will be. But with debug ON, software ECC, and no
DMA the wait is in many tens of minutes (and substantially longer
if many debug options are enabled.
[I don't yet have data for the more optimal cases. It will be
significantly less, but still not fast.]
On subsequent boots, after the NXFFS file system has been created the
delay will be less. But the NAND-related boot time can still be
substantial. This is because NXFFS needs to scan the NAND device
and build the in-memory dataset needed to access NAND. It is
recommended you create a separated thread at boot time to bring up
NXFFS so that you don't delay the boot-to-prompt time excessively.
delay will be less. When the new file system is empty, it will be
very fast. But the NAND-related boot time can become substantial when
there has been a lot of usage of the NAND. This is because NXFFS
needs to scan the NAND device and build the in-memory dataset needed
to access NAND and there is more that must be scanned after the device
has been used. You may want tocreate a separate thread at boot time
to bring up NXFFS so that you don't delay the boot-to-prompt time
excessively in these longer delay cases.
NOTE: There is another NXFFS related issue: When the FLASH is
fully used, NXFFS will restructure the entire FLASH, the delay to
@ -1433,6 +1442,38 @@ NAND Support
Application Configuration -> NSH Library
CONFIG_NSH_ARCHINIT=y : Use architecture-specific initialization
Using NAND
----------
With the options CONFIG_SAMA5_NAND_AUTOMOUNT=y and
CONFIG_SAMA5_NAND_NXFFS=y, the NAND FLASH will be mounted in the NSH
start-up logic before the NSH prompt appears. There is no feedback as
to whether or not the mount was successful. You can, however, see the
mounted file systems using the nsh 'mount' command:
nsh> mount
/mnt/nand type nxffs
Then NAND can be used like any other file system:
nsh> echo "This is a test" >/mnt/nand/atest.txt
nsh> ls -l /mnt/nand
/mnt/nand:
---x--x--x 16 atest.txt
nsh> cat /mnt/nand/atest.txt
This is a test
The NAND volume can be un-mounted with this comment:
nsh> umount /mnt/nand
nsh> mount
And re-mounted with this command:
nsh> mount -t nxffs /mnt/mystuff
nsh> mount
/mnt/mystuff type nxffs
AT24 Serial EEPROM
==================