ARM: AM335x: Kernel oops when using EDMA and MMC

[Mark Jackson]

I'm trying to get the MMC port working on our custom AM3352 CPU board.

I have added MMC entries to out dts file (similar to [1]), and I've
enabled CONFIG_TI_EDMA.

Our board boots fine without an SD card inserted ...

[    0.000000] Booting Linux on physical CPU 0x0
[    0.000000] Linux version 3.11.0-rc1-00025-g95b9b72 (mpfj at mpfj-nanobone) (gcc version 4.6.3 (Buildroot 2013.02-dirty) ) #309 Wed Jul 17 16:37:28 BST 2013
...
[    2.789028] VFS: Mounted root (ubifs filesystem) on device 0:12.
[    2.797268] devtmpfs: mounted
[    2.801032] Freeing unused kernel memory: 200K (c0551000 - c0583000)
...
Welcome to Buildroot
nanobone login:

But when I boot with a card already inserted, I get the following oops ...

...
[    1.827343] Unable to handle kernel NULL pointer dereference at virtual address 0000000c
[    1.835868] pgd = c0004000
[    1.838774] [0000000c] *pgd=00000000
[    1.842556] Internal error: Oops: 5 [#1] ARM
[    1.847063] CPU: 0 PID: 6 Comm: kworker/u2:0 Not tainted 3.11.0-rc1-00025-g95b9b72 #309
[    1.855511] Workqueue: kmmcd mmc_rescan
[    1.859556] task: cf06a080 ti: cf072000 task.ti: cf072000
[    1.865257] PC is at omap_hsmmc_start_command+0x74/0xf4
[    1.870761] LR is at omap_hsmmc_request+0xec/0x4dc
[    1.875806] pc : [<c0305b70>]    lr : [<c0306c64>]    psr: 60000113
[    1.875806] sp : cf073ca0  ip : 00000000  fp : 00000008
[    1.887885] r10: cf073de8  r9 : 00000001  r8 : cf11d918
[    1.893382] r7 : 00000003  r6 : cf33cc80  r5 : 00000001  r4 : 00000033
[    1.900250] r3 : 00020000  r2 : cf073db8  r1 : cf073d84  r0 : cf33cc80
[    1.907122] Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
[    1.914813] Control: 10c5387d  Table: 80004019  DAC: 00000015
[    1.920859] Process kworker/u2:0 (pid: 6, stack limit = 0xcf072238)
[    1.927454] Stack: (0xcf073ca0 to 0xcf074000)
[    1.932048] 3ca0: cf33c800 cf073d40 00000003 00000000 c0076a8c cf073d40 48060220 48060220
[    1.940659] 3cc0: 00000004 00000004 00000002 00000002 cf073ec8 c0421a9c c051835c cf073d40
[    1.949271] 3ce0: cf33c800 00000001 00000008 00000008 00000002 cf073db8 cf073ec8 c02f0f28
[    1.957882] 3d00: 00000200 00000064 00000000 cf073db8 cf073ec8 cf073d40 cf073d50 00000000
[    1.966493] 3d20: cf33c800 c02f18a4 cf369800 cf369a80 00000000 cf360880 00000008 c02f9964
[    1.975104] 3d40: 00000000 cf073d84 cf073db8 00000000 00000001 00000001 dead4ead ffffffff
[    1.983717] 3d60: ffffffff c0af722c c06aa3e4 00000000 c04ddadc cf073d74 cf073d74 c02f0dc4
[    1.992327] 3d80: 00000000 00000033 00000000 00000000 00000000 00000000 00000000 000000b5
[    2.000938] 3da0: 00000000 00000000 00000000 00000000 cf073db8 cf073d40 05f5e100 00000000
[    2.009548] 3dc0: 00000008 00000001 00000000 00000200 00000000 00000000 cf073d40 00000001
[    2.018159] 3de0: cf073de8 00000000 c0cf1c02 00000880 00000008 8f360880 00000000 cf369800
[    2.026771] 3e00: cf33c800 00000000 cf369800 cf073e4c cf072000 c02f8740 00000000 00000015
[    2.035382] 3e20: 00000003 cf33c800 00000000 00000000 cf369800 cf073e4c cf072000 c02f8b20
[    2.043994] 3e40: 00000002 c02f25cc 00000002 02544d53 41303447 1026c914 2600bbbd c0ff8000
[    2.052605] 3e60: c0455884 cf33c800 00000000 c0455884 c0455890 00000000 cf072000 c02f92bc
[    2.061217] 3e80: c0455890 00ff8000 00000002 cf33cb14 cf33c800 c02f3a28 cf041ac0 cf33cb14
[    2.069829] 3ea0: cf050c00 cf051c00 00000000 c00507ec 00000002 00000000 c0050778 c0050f10
[    2.078441] 3ec0: 00000000 00000000 c0af7268 c06aa1c4 00000000 c0518cd0 cf06a080 cf041ac0
[    2.087054] 3ee0: cf050c00 cf072000 cf050c30 cf041ad8 00000089 c05d7b5c cf050c00 c0050e4c
[    2.095665] 3f00: 00000000 cf072000 60000113 cf04dda8 00000000 cf041ac0 c0050d08 00000000
[    2.104276] 3f20: 00000000 00000000 00000000 c0056c94 c0429a18 00000000 00000001 cf041ac0
[    2.112888] 3f40: 00000000 00000001 dead4ead ffffffff ffffffff c05ec0a0 00000000 00000000
[    2.121499] 3f60: c04ddadc cf073f64 cf073f64 00000000 00000001 dead4ead ffffffff ffffffff
[    2.130112] 3f80: c05ec0a0 00000000 00000000 c04ddadc cf073f90 cf073f90 cf073fac cf04dda8
[    2.138724] 3fa0: c0056bf0 00000000 00000000 c0013588 00000000 00000000 00000000 00000000
[    2.147334] 3fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[    2.155946] 3fe0: 00000000 00000000 00000000 00000000 00000013 00000000 57e0c5db 5ffb7d3c
[    2.164565] [<c0305b70>] (omap_hsmmc_start_command+0x74/0xf4) from [<00000003>] (0x3)
[    2.172814] Code: 13a03801 0a00001b e590c008 e5914000 (e59cc00c)
[    2.179314] ---[ end trace 6ec9899a56aef6aa ]---

I have also noticed that when the kernel boots okay (without a card inserted), if
I then insert a card, nothing happens (even with CONFIG_MMC_DEBUG=y) ... including
no kernel oops.

Can anyone shed light on what's wrong ?

Cheers
Mark J.

[1] https://lkml.org/lkml/2013/6/25/784