[U-Boot] [PATCH 2/5] ls2080: Disable dcache during ddr init

[Prabhakar Kushwaha]

Hi Alex,


> -----Original Message-----
> From: U-Boot [mailto:u-boot-bounces at lists.denx.de] On Behalf Of
> Alexander Graf
> Sent: Friday, May 13, 2016 5:52 PM
> To: u-boot at lists.denx.de
> Subject: [U-Boot] [PATCH 2/5] ls2080: Disable dcache during ddr init
> 
> While trying something completely different I saw the DDR probe hang on
> boot reliably depending on how big my code ended up. Adding simple "nop"
> instructions in my code (completely unrelated) flow made the DDR probe
> work again.
> 
> So we're accessing some RAM - probably the page table - and rely on the
> cache to give us a correct view of the world while DRAM gets initialized.
> 
> This patch just disables dcache while we're initializing the memory controller,
> resolving all system hangs for me so far.
> 
> Signed-off-by: Alexander Graf <agraf at suse.de>
> 

While testing Linux with your patch set, I found Linux boot crashing. 

I tried git-bisect and find out this patch is creating problem
It is very strange!!

--prabhakar


[    0.000000] Booting Linux on physical CPU 0x0
[    0.000000] Initializing cgroup subsys cpu
[    0.000000] Linux version 4.1.8+ (prabhu_kush at OptiPlex-790) (gcc version 4.8.3 20131202 (prerelease) (crosstool-NG linaro-1.13.1-4.8-2013.12 - Linaro GCC 2013.11) ) #1 SMP PREEMPT Wed May 18 17:10:46 IST 2016
[    0.000000] CPU: AArch64 Processor [411fd071] revision 1
[    0.000000] Detected PIPT I-cache on CPU0
[    0.000000] alternatives: enabling workaround for ARM erratum 832075
[    0.000000] alternatives: enabling workaround for ARM erratum 834220
[    0.000000] earlycon: Early serial console at MMIO 0x21c0600 (options '')
[    0.000000] bootconsole [uart0] enabled
[    0.000000] Bad mode in Error handler detected, code 0xbf000000 -- SError
[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.1.8+ #1
[    0.000000] Hardware name: Freescale Layerscape 2080a RDB Board (DT)
[    0.000000] task: ffff800000b38fc0 ti: ffff800000b2c000 task.ti: ffff800000b2c000
[    0.000000] PC is at setup_arch+0x294/0x5cc
[    0.000000] LR is at setup_arch+0x290/0x5cc
[    0.000000] pc : [<ffff800000aa8610>] lr : [<ffff800000aa860c>] pstate: 000002c5
[    0.000000] sp : ffff800000b2ff30
[    0.000000] x29: ffff800000b2ff30 x28: 00000000a00000e0
[    0.000000] x27: ffff800000081210 x26: 0000000080c70000
[    0.000000] x25: 0000000080c6d000 x24: 0000000080000000
[    0.000000] x23: ffff800000b32000 x22: 0000000000000000
[    0.000000] x21: ffff800000b2ffe8 x20: ffff800000b32000
[    0.000000] x19: ffff800000080000 x18: 0000000001002222
[    0.000000] x17: 0000000000000000 x16: 0000000003010066
[    0.000000] x15: ffffffffffffffff x14: 0ffffffffffffffe
[    0.000000] x13: 0000000000000020 x12: 0000000000000008
[    0.000000] x11: 0000000000000004 x10: 0101010101010101
[    0.000000] x9 : fefefefefefefeff x8 : 7f7f7f7f7f7f7f7f
[    0.000000] x7 : 6466606f64667467 x6 : 0b1a09161f0d0265
[    0.000000] x5 : 65020d1f16091a0b x4 : 0000000000000000
[    0.000000] x3 : 36f6e736f6c65000 x2 : 0000000000000087
[    0.000000] x1 : 0000000000000000 x0 : 0000000000000001
[    0.000000]
[    0.000000] Internal error: Oops - bad mode: 0 [#1] PREEMPT SMP
[    0.000000] Modules linked in:
[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.1.8+ #1
[    0.000000] Hardware name: Freescale Layerscape 2080a RDB Board (DT)
[    0.000000] task: ffff800000b38fc0 ti: ffff800000b2c000 task.ti: ffff800000b2c000
[    0.000000] PC is at setup_arch+0x294/0x5cc
[    0.000000] LR is at setup_arch+0x290/0x5cc
[    0.000000] pc : [<ffff800000aa8610>] lr : [<ffff800000aa860c>] pstate: 000002c5
[    0.000000] sp : ffff800000b2ff30
[    0.000000] x29: ffff800000b2ff30 x28: 00000000a00000e0
[    0.000000] x27: ffff800000081210 x26: 0000000080c70000
[    0.000000] x25: 0000000080c6d000 x24: 0000000080000000
[    0.000000] x23: ffff800000b32000 x22: 0000000000000000
[    0.000000] x21: ffff800000b2ffe8 x20: ffff800000b32000
[    0.000000] x19: ffff800000080000 x18: 0000000001002222
[    0.000000] x17: 0000000000000000 x16: 0000000003010066
[    0.000000] x15: ffffffffffffffff x14: 0ffffffffffffffe
[    0.000000] x13: 0000000000000020 x12: 0000000000000008
[    0.000000] x11: 0000000000000004 x10: 0101010101010101
[    0.000000] x9 : fefefefefefefeff x8 : 7f7f7f7f7f7f7f7f
[    0.000000] x7 : 6466606f64667467 x6 : 0b1a09161f0d0265
[    0.000000] x5 : 65020d1f16091a0b x4 : 0000000000000000
[    0.000000] x3 : 36f6e736f6c65000 x2 : 0000000000000087
[    0.000000] x1 : 0000000000000000 x0 : 0000000000000001
[    0.000000]
[    0.000000] Process swapper (pid: 0, stack limit = 0xffff800000b2c020)
[    0.000000] Stack: (0xffff800000b2ff30 to 0xffff800000b30000)
[    0.000000] ff20:                                     00b2ffa0 ffff8000 00aa5684 ffff8000
[    0.000000] ff40: 00000001 00000000 00adfb20 ffff8000 9fff9000 00000000 00000000 00000000
[    0.000000] ff60: 00b32000 ffff8000 80000000 00000000 80c6d000 00000000 80c70000 00000000
[    0.000000] ff80: ffffffff ffffffff 00000000 00000000 00000080 00000000 fefefefe fefefefe
[    0.000000] ffa0: 00000000 00000000 800826a0 00000000 fff9e7c0 00000000 00000e12 00000000
[    0.000000] ffc0: 9fff9000 00000000 00000000 00000000 00000000 00000000 80000000 00000000
[    0.000000] ffe0: 00000000 00000000 00ae0348 ffff8000 00000000 00000000 00000000 00000000
[    0.000000] Call trace:
[    0.000000] [<ffff800000aa8610>] setup_arch+0x294/0x5cc
[    0.000000] [<ffff800000aa5680>] start_kernel+0x94/0x3bc
[    0.000000] Code: 940009db 94000957 97fff3e4 d50344ff (9400066f)
[    0.000000] ---[ end trace cb88537fdc8fa200 ]---
[    0.000000] Kernel panic - not syncing: Attempted to kill the idle task!
[    0.000000] ---[ end Kernel panic - not syncing: Attempted to kill the idle task!