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disable_anatop_clocks in clk-imx6q.c causes hang for lpddr2 board.

Question asked by Gautam Bhat on Aug 21, 2016
Latest reply on Aug 29, 2016 by Gautam Bhat


I have a custom board which has an lpddr2 working at 200MHz. (Tested with android kitkat).  I am trying to boot the NXP provided Android Marshmallow with the necessary changes needed for our board. I have setup the DCD file by running the LPDDR2 stress test calibration. The only change I did in the DCD file is to set the

DATA 4, 0x020c4018, 0x000e0324 for 200MHz instead of DATA 4, 0x020c4018, 0x00060324 for the 400 MHz.


When I enabled earlyprintk and debugging in the kernel I found that it gets stuck near CCM initialization (tracing from clk.c to clk-imx6q.c). I finally found that it hangs at disable_anatop_clocks in clk-imx6q.c). If I set the reg to 0x8080 in the check where IMX6QDL_CLK_PREIPH_PRE parent is IMX6QDL_CLK_PLL2_PFD2_396M which fails then the board boots up with binder throwing timerqueue_add error in android and finally crashes.


After searching on the net I find in the mailing list that the ldb glitchless bug initialization was recently added. In my case I think it is disabling PLL2PFD2 which is used as memory clock (divided by 2) as per the DCD value shown above.



For reference I will paste the kernel log below:

Starting kernel ...

Uncompressing Linux... done, booting the kernel.
Booting Linux on physical CPU 0x0
Initializing cgroup subsys cpu
Initializing cgroup subsys cpuacct
Linux version 3.14.52-141398-gad65770-dirty (xxxx@xxxxx) (gcc version 4.9.x-google 20140827 (prerelease) (GCC) ) #33 SMP 
PREEMPT Sun Aug 21 17:15:17 IST 2016
CPU: ARMv7 Processor [412fc09a] revision 10 (ARMv7), cr=10c5387d
CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
Machine model: Freescale i.MX6 DualLite Roche Solaris HH Board
bootconsole [earlycon0] enabled
cma: CMA: reserved 320 MiB at 2a000000
Memory policy: Data cache writealloc
PERCPU: Embedded 9 pages/cpu @ef729000 s13312 r8192 d15360 u36864
Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 522511
Kernel command line: console=ttymxc0,115200 earlyprintk
PID hash table entries: 4096 (order: 2, 16384 bytes)
Dentry cache hash table entries: 131072 (order: 7, 524288 bytes)
Inode-cache hash table entries: 65536 (order: 6, 262144 bytes)
Memory: 1732660K/2096124K available (10724K kernel code, 789K rwdata, 3820K rodata, 593K init, 766K bss, 363464K reserved, 1317884K highmem)
Virtual kernel memory layout:
    vector  : 0xffff0000 - 0xffff1000   (   4 kB)
    fixmap  : 0xfff00000 - 0xfffe0000   ( 896 kB)
    vmalloc : 0xf0000000 - 0xff000000   ( 240 MB)
    lowmem  : 0xc0000000 - 0xef800000   ( 760 MB)
    pkmap   : 0xbfe00000 - 0xc0000000   (   2 MB)
    modules : 0xbf000000 - 0xbfe00000   (  14 MB)
      .text : 0xc0008000 - 0xc0e3c550   (14546 kB)
      .init : 0xc0e3d000 - 0xc0ed1400   ( 593 kB)
      .data : 0xc0ed2000 - 0xc0f976ac   ( 790 kB)
       .bss : 0xc0f976ac - 0xc1057024   ( 767 kB)
SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=2, Nodes=1
Preemptible hierarchical RCU implementation.
        RCU restricting CPUs from NR_CPUS=4 to nr_cpu_ids=2.
RCU: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=2
NR_IRQS:16 nr_irqs:16 16
L310 cache controller enabled
l2x0: 16 ways, CACHE_ID 0x410000c8, AUX_CTRL 0x32050000, Cache size: 512 kB




Can somebody help me in solving this issue. How do I make the IMX6QDL_CLK_PREIPH_PRE parent of IMX6QDL_CLK_PLL2_PFD2_396M?