something gets odd when I set the

Peter Pan pppeterpppan at
Tue Mar 2 14:18:21 EST 2010

Problem solved. The NULL oops is due to the mtd->dev.class->p is NULL,
which makes the spin_lock in "get_device_parent" function uses a false
spin_lock_t struct.
the line is "spin_lock(&dev->class->p->class_dirs.list_lock);"
That is mainly because in function add_mtd_device function uses the
static struct mtd_class to fill into mtd->dev.class. The static struct
is not initialized because I drop the driver in our custom dirctory,
which is in /arch/powerpc/platforms/..., not in the /drivers/mtd/nand
directory, after I put the file there and modifies the Makefile,
everything works fine.

2010/3/2 Peter Pan <pppeterpppan at>:
> We use Address A20 and A21 connect to ALE and CLE, the data bus is
> connected through a buffer.
> The RE is OE AND with CS. the WE is PBS0 AND with CS. CE pin is
> connect to ground. It works
> fine in VxWorks. And also in our previous Linux version 2.6.22.
> Now, I get a odd problem. My GPCM Nand flash driver is mostly copied
> from fsl_upm.c. In the fun_probe
> function, I have printed out the of_device pointer status as follows:
> ofdev= 0xcf851ca0
> ofdev->dev= 0xcf851cb0
> ofdev->dev.class= 0xcf851d50
> Then I set the &ofdev->dev to using
> fun-> = &ofdev->dev;
> Then I print out the values:
> fun-> 0xcf851cb0
> fun->>class= 0x0
> The parent pointer is identical, but the class member is NULL, which
> makes the access of NULL pointer oops
> later.
> I'm wondering why this could happen. The pointer points at the same
> address, shouldn't all the members be the
> same?

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