I'm struggling to debug an issue where the kernel is unable to
find a JFFS2 partition held in NOR flash (on CS0)

Under U-Boot, I can get a directory listing of the partition:-

U-Boot# chpart nor0,4
partition changed to nor0,4
U-Boot# ls
Scanning JFFS2 FS: ....... done.
 drwxrwxr-x        0 Wed Jun 19 16:27:26 2013 bin
 drwxr-xr-x        0 Tue Apr 30 08:21:26 2013 dev
 drwxr-xr-x        0 Tue Apr 23 14:19:13 2013 etc
 drwxrwxr-x        0 Tue Apr 30 08:21:26 2013 home
 drwxrwxr-x        0 Wed Jun 19 16:27:26 2013 lib
 lrwxrwxrwx       11 Wed May 01 07:53:12 2013 linuxrc -> bin/busybox
 drwxrwxr-x        0 Mon Jan 28 14:54:31 2013 media
 drwxrwxr-x        0 Mon Jan 28 14:54:31 2013 mnt
 drwxrwxr-x        0 Mon Apr 29 13:20:55 2013 nano
 drwxrwxr-x        0 Mon Jan 28 14:54:31 2013 opt
 drwxrwxr-x        0 Mon Jan 28 14:54:31 2013 proc
 drwxrwxr-x        0 Mon Jan 28 14:54:31 2013 root
 lrwxrwxrwx        3 Mon Jan 28 14:54:31 2013 run -> tmp
 drwxr-xr-x        0 Wed Jun 19 16:27:26 2013 sbin
 drwxrwxr-x        0 Mon Jan 28 14:54:31 2013 sys
 drwxrwxrwt        0 Tue Apr 30 08:21:13 2013 tmp
 drwxrwxr-x        0 Tue Apr 30 14:52:55 2013 usr
 drwxrwxr-x        0 Tue Apr 30 08:19:05 2013 var

And here is the partition table (according to U-Boot):-

U-Boot# mtdparts

device nor0 <nor>, # parts = 6
 #: name                size            offset          mask_flags
 0: u-boot              0x000c0000      0x00000000      0
 1: u-boot-env1         0x00020000      0x000c0000      0
 2: u-boot-env2         0x00020000      0x000e0000      0
 3: kernel              0x00400000      0x00100000      0
 4: rootfs              0x03b00000      0x00500000      0
 5: data                0x04000000      0x04000000      0

active partition: nor0,4 - (rootfs) 0x03b00000 @ 0x00500000

defaults:
mtdids  : nor0=nor
mtdparts: mtdparts=nor:768k(u-boot),128k(u-boot-env1),128k(u-boot-env2),4m(kernel),59m(rootfs),64m(data)

Now, when I boot the kernel, it can see all the partitions:-

Starting kernel ...

[    0.000000] Booting Linux on physical CPU 0x0
[    0.000000] Linux version 3.10.0-rc4-00172-gf31c62e-dirty (mpfj@mpfj-nanobone) (gcc version 4.8.1 (Buildroot 2013.08-git-00253-g21736a6-dirty) ) #236 Thu Jun 20 10:08:37 BST 2013
[    0.000000] CPU: ARMv7 Processor [413fc082] revision 2 (ARMv7), cr=10c53c7d
[    0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[    0.000000] Machine: Generic AM33XX (Flattened Device Tree), model: Newflow AM335x NanoBone
...
[    0.000000] Kernel command line: earlyprintk debug console=ttyO0,115200n8 noinitrd ip=off mem=256M rootwait=1 rootfstype=jffs2 root=/dev/mtdblock4 ignore_loglevel
...
[    1.055035] spansion,s29gl010p11t: Found 1 x16 devices at 0x0 in 16-bit bank. Manufacturer ID 0x002276 Chip ID 0x00023c
[    1.066567] Amd/Fujitsu Extended Query Table at 0x0040
[    1.071998]   Amd/Fujitsu Extended Query version 1.3.
[    1.077374] number of CFI chips: 1
[    1.081178] 6 ofpart partitions found on MTD device spansion,s29gl010p11t
[    1.088371] Creating 6 MTD partitions on "spansion,s29gl010p11t":
[    1.094805] 0x000000000000-0x0000000c0000 : "boot"
[    1.103834] 0x0000000c0000-0x0000000e0000 : "env1"
[    1.111011] 0x0000000e0000-0x000000100000 : "env2"
[    1.118004] 0x000000100000-0x000000500000 : "kernel"
[    1.125067] 0x000000500000-0x000004000000 : "rootfs"
[    1.132201] 0x000004000000-0x000008000000 : "data"

I've also added some debug to make sure offset 0x00500000 points to
a valid JFFS2 image (magic marker = 0x1985):-

[    1.401600] phys = 08500000, virt = d08f4000, data = 1985

But, although I specify "root=/dev/mtdblock4", I get the error:-

[    1.419912] List of all partitions:
[    1.423644] No filesystem could mount root, tried:  jffs2
[    1.429522] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

Can anyone shed some light on what might be wrong ?

Is there anything extra to try ?

I've attached my config.

Cheers
Mark J.