[Letux-kernel] 2GB vs. 4GB Pyra RAM tests

[H. Nikolaus Schaller]

Hi Tony,

> Am 27.07.2017 um 16:19 schrieb Tony Lindgren <tony at atomide.com>:
> 
> Hi,
> 
> * H. Nikolaus Schaller <hns at goldelico.com> [170727 07:13]:
>> Now comes the difficult interpretation.
>> * generally this 4GB Pyra is less stable. Could be RAM induced
>>  or something else. The test does not give a clear indication.
>> * the 2GB Pyra runs stable in all configurations
>> * 4GB and LPAE makes Linux boot fail more often
>> * it is possible to use the complete 4GB RAM, but not reliably
>> 
>> So I suspect a mixture of multiple effects. One makes the 4GB
>> device I have tested less stable.
>> 
>> And the other could be an LPAE issue that makes 4GB only useable
>> in certain good cases (I could imagine it depends on how the
>> virtual paging mechanism randomly allocates RAM). But it could
>> still be the 4GB RAM chips or config being less stable due to
>> higher noise or power consumption or whatever.
>> 
>> Attached is an excerpt of the boot log and successful 3GB memtester
>> output (the "BUG" occurs for non-lpae kernel as well - so it is not
>> influencing the outcome).
> 
> Here are two suggestions to try to narrow this down a bit:
> 
> 1. Try with just 1GB of 4GB enabled instead of 2GB to see if
>   that works reliably

Well, I tried but was not able to easily tweak U-Boot to use just 1GB.
U-Boot did hang then.

What I could do was to use 2GB in first + 100M in second bank. This
appears to show the same issues.

> 
> 2. Revert commit 7abdb0e23e7b ("ARM: OMAP5: Add basic cpuidle
>   MPU CSWR support") to see if it's somehow PM related

Didn't show a noticeable effect either.

Just a note: what I see since 4.13-rc1 is

[    2.151973] omap_vc_init_channel: No PMIC info for vdd_core
[    2.157937] omap_vp_init: No PMIC info for vdd_core
[    2.163111] omap_vc_init_channel: No PMIC info for vdd_mm
[    2.168767] omap_vp_init: No PMIC info for vdd_mm
[    2.173800] omap_vc_init_channel: No PMIC info for vdd_mpu
[    2.179612] omap_vp_init: No PMIC info for vdd_mpu
[    2.185218] Power Management for TI OMAP4+ devices.
[    2.190520] BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1
[    2.198816] caller is pwrdm_set_next_pwrst+0x48/0x1d8
[    2.204151] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.13.0-rc3-letux-lpae+ #1315
[    2.212082] Hardware name: Generic OMAP5 (Flattened Device Tree)
[    2.218388] [<c020eae0>] (unwind_backtrace) from [<c020afec>] (show_stack+0x10/0x14)
[    2.226503] [<c020afec>] (show_stack) from [<c084bee8>] (dump_stack+0x98/0xd0)
[    2.234080] [<c084bee8>] (dump_stack) from [<c0552588>] (check_preemption_disabled+0xec/0x124)
[    2.243106] [<c0552588>] (check_preemption_disabled) from [<c022030c>] (pwrdm_set_next_pwrst+0x48/0x1d8)
[    2.253050] [<c022030c>] (pwrdm_set_next_pwrst) from [<c0e0cdf0>] (omap4_mpuss_init+0xb4/0x23c)
[    2.262169] [<c0e0cdf0>] (omap4_mpuss_init) from [<c0e0d20c>] (omap4_pm_init+0xf4/0x164)
[    2.270656] [<c0e0d20c>] (omap4_pm_init) from [<c0e0a414>] (omap5_init_late+0x10/0x18)
[    2.278953] [<c0e0a414>] (omap5_init_late) from [<c0e03560>] (init_machine_late+0x1c/0x90)
[    2.287622] [<c0e03560>] (init_machine_late) from [<c02018d8>] (do_one_initcall+0xa8/0x150)
[    2.294441] ata1: SATA link down (SStatus 0 SControl 300)
[    2.302015] [<c02018d8>] (do_one_initcall) from [<c0e00d94>] (kernel_init_freeable+0x110/0x1d4)
[    2.311136] [<c0e00d94>] (kernel_init_freeable) from [<c085d518>] (kernel_init+0x8/0x10c)
[    2.319703] [<c085d518>] (kernel_init) from [<c0206ee8>] (ret_from_fork+0x14/0x2c)
[    2.327714] BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1
[    2.335959] caller is pwrdm_set_next_pwrst+0x48/0x1d8
[    2.341255] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.13.0-rc3-letux-lpae+ #1315
[    2.349181] Hardware name: Generic OMAP5 (Flattened Device Tree)
[    2.355483] [<c020eae0>] (unwind_backtrace) from [<c020afec>] (show_stack+0x10/0x14)
[    2.363596] [<c020afec>] (show_stack) from [<c084bee8>] (dump_stack+0x98/0xd0)
[    2.371166] [<c084bee8>] (dump_stack) from [<c0552588>] (check_preemption_disabled+0xec/0x124)
[    2.380191] [<c0552588>] (check_preemption_disabled) from [<c022030c>] (pwrdm_set_next_pwrst+0x48/0x1d8)
[    2.390132] [<c022030c>] (pwrdm_set_next_pwrst) from [<c0e0ce6c>] (omap4_mpuss_init+0x130/0x23c)
[    2.399346] [<c0e0ce6c>] (omap4_mpuss_init) from [<c0e0d20c>] (omap4_pm_init+0xf4/0x164)
[    2.407824] [<c0e0d20c>] (omap4_pm_init) from [<c0e0a414>] (omap5_init_late+0x10/0x18)
[    2.416126] [<c0e0a414>] (omap5_init_late) from [<c0e03560>] (init_machine_late+0x1c/0x90)
[    2.424782] [<c0e03560>] (init_machine_late) from [<c02018d8>] (do_one_initcall+0xa8/0x150)
[    2.433532] [<c02018d8>] (do_one_initcall) from [<c0e00d94>] (kernel_init_freeable+0x110/0x1d4)
[    2.442652] [<c0e00d94>] (kernel_init_freeable) from [<c085d518>] (kernel_init+0x8/0x10c)
[    2.451220] [<c085d518>] (kernel_init) from [<c0206ee8>] (ret_from_fork+0x14/0x2c)
[    2.459611] ThumbEE CPU extension supported.
[    2.464157] Registering SWP/SWPB emulation handler
[    2.475414] mmc0: new high speed MMC card at address 0001
[    2.483023] mmcblk0: mmc0:0001 HBG4a2 29.1 GiB 
[    2.488487] mmcblk0boot0: mmc0:0001 HBG4a2 partition 1 4.00 MiB
[    2.495345] mmcblk0boot1: mmc0:0001 HBG4a2 partition 2 4.00 MiB

I had hoped that 0e4097c3354e2f5a5ad8affd9dc7f7f7d00bb6b9 also fixes this
but it did not in 4.13-rc3.

BR,
Nikolaus