usb: musb: fix kernel oops when loading musb_hdrc module for the 2nd time

musb driver still may write MUSB_DEVCTL register after clock is disabled
in musb_platform_exit, which may cause the kernel oops[1] when musb_hdrc
module is loaded for the 2nd time.

The patch fixes the kernel oops in this case.

[1] kernel oops when loading musb_hdrc module for the 2nd time

[   93.380279] musb_hdrc: version 6.0, musb-dma, otg (peripheral+host), debug=5
[   93.387847] bus: 'platform': add driver musb_hdrc
[   93.388153] bus: 'platform': driver_probe_device: matched device musb_hdrc with driver musb_hdrc
[   93.388183] bus: 'platform': really_probe: probing driver musb_hdrc with device musb_hdrc
[   93.405090] HS USB OTG: revision 0x33, sysconfig 0x2010, sysstatus 0x1, intrfsel 0x1, simenable  0x0
[   93.405364] musb_hdrc: ConfigData=0xde (UTMI-8, dyn FIFOs, bulk combine, bulk split, HB-ISO Rx, HB-ISO Tx, SoftConn)
[   93.405395] musb_hdrc: MHDRC RTL version 1.400
[   93.405426] musb_hdrc: setup fifo_mode 3
[   93.405456] musb_hdrc: 7/31 max ep, 3648/16384 memory
[   93.405487] musb_core_init 1524: musb_hdrc: hw_ep 0shared, max 64
[   93.405487] musb_core_init 1524: musb_hdrc: hw_ep 1tx, doublebuffer, max 512
[   93.405517] musb_core_init 1533: musb_hdrc: hw_ep 1rx, doublebuffer, max 512
[   93.405548] musb_core_init 1524: musb_hdrc: hw_ep 2tx, max 512
[   93.405578] musb_core_init 1533: musb_hdrc: hw_ep 2rx, max 512
[   93.405578] musb_core_init 1524: musb_hdrc: hw_ep 3shared, max 256
[   93.405609] musb_core_init 1524: musb_hdrc: hw_ep 4shared, max 256
[   93.405853] musb_platform_try_idle 133: b_idle inactive, for idle timer for 7 ms
[   93.405944] device: 'gadget': device_add
[   93.406921] PM: Adding info for No Bus:gadget
[   93.406951] musb_init_controller 2136: OTG mode, status 0, dev80
[   93.407379] musb_do_idle 51: musb_do_idle: state=1
[   93.408233] musb_hdrc musb_hdrc: USB OTG mode controller at fa0ab000 using DMA, IRQ 92
[   93.416656] driver: 'musb_hdrc': driver_bound: bound to device 'musb_hdrc'
[   93.416687] bus: 'platform': really_probe: bound device musb_hdrc to driver musb_hdrc
[  124.486938] bus: 'platform': remove driver musb_hdrc
[  124.490509] twl4030_usb twl4030_usb: twl4030_phy_suspend
[  124.491424] device: 'gadget': device_unregister
[  124.491424] PM: Removing info for No Bus:gadget
[  124.495269]  gadget: musb_gadget_release
[  124.498992] driver: 'musb_hdrc': driver_release
[  129.569366] musb_hdrc: version 6.0, musb-dma, otg (peripheral+host), debug=5
[  129.576934] bus: 'platform': add driver musb_hdrc
[  129.577209] bus: 'platform': driver_probe_device: matched device musb_hdrc with driver musb_hdrc
[  129.577239] bus: 'platform': really_probe: probing driver musb_hdrc with device musb_hdrc
[  129.592651] twl4030_usb twl4030_usb: twl4030_phy_resume
[  129.592681] Unhandled fault: external abort on non-linefetch (0x1028) at 0xfa0ab404
[  129.600830] Internal error: : 1028 [#1]
[  129.604858] last sysfs file: /sys/devices/platform/i2c_omap.3/i2c-3/i2c-dev/i2c-3/dev
[  129.613067] Modules linked in: musb_hdrc(+) [last unloaded: musb_hdrc]
[  129.619964] CPU: 0    Not tainted  (2.6.36-next-20101021+ #372)
[  129.626281] PC is at musb_platform_init+0xb0/0x1c8 [musb_hdrc]
[  129.632415] LR is at mark_held_locks+0x64/0x94
[  129.637084] pc : [<bf032198>]    lr : [<c00ad7c4>]    psr: 20000013
[  129.637084] sp : c6d5fcb0  ip : c6d5fc38  fp : c6d5fcd4
[  129.649139] r10: c6e72180  r9 : fa0ab000  r8 : c05612e8
[  129.654602] r7 : 0000005c  r6 : c0559cc8  r5 : c6e72180  r4 : c0561548
[  129.661468] r3 : 04d60047  r2 : fa0ab000  r1 : c07169d8  r0 : 00000000
[  129.668304] Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
[  129.675811] Control: 10c5387d  Table: 86e4c019  DAC: 00000015
[  129.681823] Process insmod (pid: 554, stack limit = 0xc6d5e2f0)
[  129.688049] Stack: (0xc6d5fcb0 to 0xc6d60000)
[  129.692626] fca0:                                     fa0ab000 c0555c54 c6d5fcd4 c0561548
[  129.701202] fcc0: 00000003 c05612e0 c6d5fe04 c6d5fcd8 bf03140c bf0320f4 c6d5fd9c c6d5fce8
[  129.709808] fce0: c015cb94 c041448c c06d9d10 ffffffff c6d5fd14 c6d5fd00 c00adbec c6d5fd40
[  129.718383] fd00: c015d478 c6d5fdb0 c6d5fd24 c00a9d18 c6d5e000 60000013 bf02a4ac c05612bc
[  129.726989] fd20: c0414fb4 c00a9cf0 c6d5fd54 c6d5fd38 c015bbdc c0244280 c6e8b7b0 c7929330
[  129.735565] fd40: c6d5fdb0 c6d5fdb0 c6d5fd7c c6e7227c c015c010 c015bb90 c015c2ac c6d5fdb0
[  129.744171] fd60: c7929330 c6d5fdb0 c7929330 c6e8b7b0 c6d5fd9c 00000000 c7929330 c6e8b7b0
[  129.752746] fd80: c6d5fdb0 00000000 00000001 00000000 c6d5fde4 c6d5fda0 c015d478 c015cb74
[  129.761322] fda0: c056138c 00000000 c6d5fdcc c6d5fdb8 c7929330 00000000 c056138c c05612e8
[  129.769927] fdc0: 00000000 c05612f0 c0c5d62c c06f6e00 c73217c0 00000000 c6d5fdf4 c05612e8
[  129.778503] fde0: c05612e8 bf02a2e4 c0c5d62c c06f6e00 c73217c0 00000000 c6d5fe14 c6d5fe08
[  129.787109] fe00: c029a398 bf0311c8 c6d5fe4c c6d5fe18 c0299120 c029a384 c7919140 22222222
[  129.795684] fe20: c6d5fe4c c05612e8 c056131c bf02a2e4 c0299278 c06f6e00 c73217c0 00000000
[  129.804290] fe40: c6d5fe6c c6d5fe50 c0299314 c0299020 00000000 c6d5fe70 bf02a2e4 c0299278
[  129.812866] fe60: c6d5fe94 c6d5fe70 c02987d4 c0299284 c7825060 c78c6618 00000000 bf02a2e4
[  129.821441] fe80: c06e4c98 00000000 c6d5fea4 c6d5fe98 c0298ea4 c0298778 c6d5fedc c6d5fea8
[  129.830047] fea0: c0297f84 c0298e8c bf02716c 000b9008 bf02a2e4 bf02a2d0 000b9008 bf02a2e4
[  129.838623] fec0: 00000000 c06f6e00 bf031000 00000000 c6d5fefc c6d5fee0 c0299614 c0297ec0
[  129.847229] fee0: bf02a2d0 000b9008 bf02a388 00000000 c6d5ff0c c6d5ff00 c029a868 c02995a8
[  129.855804] ff00: c6d5ff24 c6d5ff10 c029a88c c029a818 0010281c 000b9008 c6d5ff34 c6d5ff28
[  129.864410] ff20: bf03104c c029a878 c6d5ff7c c6d5ff38 c00463dc bf03100c 00000000 00000000
[  129.872985] ff40: 00000000 0010281c 000b9008 bf02a388 00000000 0010281c 000b9008 bf02a388
[  129.881591] ff60: 00000000 c00521c8 c6d5e000 00000000 c6d5ffa4 c6d5ff80 c00bb9b8 c00463ac
[  129.890167] ff80: c00adc88 c00ada68 00097e8e bebbfcf4 0010281c 00000080 00000000 c6d5ffa8
[  129.898742] ffa0: c0052000 c00bb908 00097e8e bebbfcf4 402c9008 0010281c 000b9008 bebbfe5a
[  129.907348] ffc0: 00097e8e bebbfcf4 0010281c 00000080 00000014 bebbfcf4 bebbfe06 0000005b
[  129.915924] ffe0: bebbf9a0 bebbf990 0001a108 40263ec0 60000010 402c9008 011b0000 0000007c
[  129.924499] Backtrace:
[  129.927185] [<bf0320e8>] (musb_platform_init+0x0/0x1c8 [musb_hdrc]) from [<bf03140c>] (musb_probe+0x250/0xf2c [musb_hdrc])
[  129.938781]  r6:c05612e0 r5:00000003 r4:c0561548
[  129.943695] [<bf0311bc>] (musb_probe+0x0/0xf2c [musb_hdrc]) from [<c029a398>] (platform_drv_probe+0x20/0x24)
[  129.954040] [<c029a378>] (platform_drv_probe+0x0/0x24) from [<c0299120>] (driver_probe_device+0x10c/0x264)
[  129.964172] [<c0299014>] (driver_probe_device+0x0/0x264) from [<c0299314>] (__driver_attach+0x9c/0xa0)
[  129.973968] [<c0299278>] (__driver_attach+0x0/0xa0) from [<c02987d4>] (bus_for_each_dev+0x68/0x94)
[  129.983367]  r7:c0299278 r6:bf02a2e4 r5:c6d5fe70 r4:00000000
[  129.989349] [<c029876c>] (bus_for_each_dev+0x0/0x94) from [<c0298ea4>] (driver_attach+0x24/0x28)
[  129.998565]  r7:00000000 r6:c06e4c98 r5:bf02a2e4 r4:00000000
[  130.004547] [<c0298e80>] (driver_attach+0x0/0x28) from [<c0297f84>] (bus_add_driver+0xd0/0x274)
[  130.013671] [<c0297eb4>] (bus_add_driver+0x0/0x274) from [<c0299614>] (driver_register+0x78/0x158)
[  130.023101] [<c029959c>] (driver_register+0x0/0x158) from [<c029a868>] (platform_driver_register+0x5c/0x60)
[  130.033325]  r7:00000000 r6:bf02a388 r5:000b9008 r4:bf02a2d0
[  130.039276] [<c029a80c>] (platform_driver_register+0x0/0x60) from [<c029a88c>] (platform_driver_probe+0x20/0xa8)
[  130.050018] [<c029a86c>] (platform_driver_probe+0x0/0xa8) from [<bf03104c>] (musb_init+0x4c/0x54 [musb_hdrc])
[  130.060424]  r5:000b9008 r4:0010281c
[  130.064239] [<bf031000>] (musb_init+0x0/0x54 [musb_hdrc]) from [<c00463dc>] (do_one_initcall+0x3c/0x1c0)
[  130.074218] [<c00463a0>] (do_one_initcall+0x0/0x1c0) from [<c00bb9b8>] (sys_init_module+0xbc/0x1d0)
[  130.083709] [<c00bb8fc>] (sys_init_module+0x0/0x1d0) from [<c0052000>] (ret_fast_syscall+0x0/0x3c)
[  130.093109]  r7:00000080 r6:0010281c r5:bebbfcf4 r4:00097e8e
[  130.099090] Code: 0a000046 e3a01001 e12fff33 e59520e4 (e5923404)
[  130.105621] ---[ end trace 1d0bd69deb79164d ]---

Cc: Ajay Kumar Gupta <ajay.gupta@ti.com>
Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Anand Gadiyar <gadiyar@ti.com>
Cc: stable@kernel.org
Signed-off-by: NMing Lei <tom.leiming@gmail.com>
Signed-off-by: NFelipe Balbi <balbi@ti.com>

drivers/usb/musb/musb_core.c

@@ -1056,7 +1056,6 @@ static void musb_shutdown(struct platform_device *pdev)
 		usb_remove_hcd(musb_to_hcd(musb));
 	musb_writeb(musb->mregs, MUSB_DEVCTL, 0);
 	musb_platform_exit(musb);
-	musb_writeb(musb->mregs, MUSB_DEVCTL, 0);
 
 	/* FIXME power down */
 }