On 08.12.2014 23:53, Scott Wood wrote:
=> nand device
Device 0: 2x nand0, sector size 128 KiB
Page size 2048 b
OOB size 64 b
Erase size 131072 b
Shouldn't you see "Device 0" and "Device 1" ?
The "2x" indicates that there are two identical chips being treated as
a single device (chip->numchips).
Is that correct ? What if I have two different NAND chips on this
controller?
Then they need to be represented as separate NAND devices, rather than
multiple chips on one device.
Gee, I wouldn't have though of that, really ;-)
Well, you asked a vague question...
So is this patch correct or not ?
In all its details? I don't know, as I'm not familiar with the
hardware. With regards to the question about non-identical devices,
this patch doesn't add support for that. So it's a question of what the
requirements are, and whether it's being used in the right
circumstances. If you have non-identical NAND chips, make sure
CONFIG_SYS_NAND_MAX_CHIPS is 1.
Correct. Using CONFIG_SYS_NAND_MAX_CHIPS support identical chips. This
is exactly what I need in my case. And is also needed for NAND devices
that have multiple NAND chips embedded on one die. You then need this
possibility to support multiple chips. Otherwise not the whole device
can be accessed.
A better question might be, does this approach make sense, versus
implementing support for multiple devices? What does Linux support?
Linux does it exactly in the same way:
[ 1.089439] nand: device found, Manufacturer ID: 0x2c, Chip ID: 0xdc
[ 1.095864] nand: Micron MT29F4G08ABADAH4
[ 1.099896] nand: 512MiB, SLC, page size: 2048, OOB size: 64
[ 1.105871] nand: 2 chips detected
...
And exposes those 2 chips as one NAND device. By using this patch we
also use the same MTD partitioning in U-Boot and Linux (mtdparts
environment).
I hope now all is clear.
Thanks,
Stefan
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