Hello Krzysztof,
On 06/14/2015 10:56 AM, Krzysztof Kozłowski wrote:
2014-11-25 15:21 GMT+09:00 Kevin Hilman khilman@kernel.org:
From: Kevin Hilman khilman@linaro.org
Using the current exynos_defconfig on the exynos5422-odroid-xu3, only 6 of 8 CPUs come online with MCPM boot. CPU0 is an A7, CPUs 1-4 are A15s and CPU5-7 are the other A7s, but with the current code, CPUs 5 and 7 do not boot:
[...] Exynos MCPM support installed CPU1: update cpu_capacity 1535 CPU1: thread -1, cpu 0, socket 0, mpidr 80000000 CPU2: update cpu_capacity 1535 CPU2: thread -1, cpu 1, socket 0, mpidr 80000001 CPU3: update cpu_capacity 1535 CPU3: thread -1, cpu 2, socket 0, mpidr 80000002 CPU4: update cpu_capacity 1535 CPU4: thread -1, cpu 3, socket 0, mpidr 80000003 CPU5: failed to come online CPU6: update cpu_capacity 448 CPU6: thread -1, cpu 2, socket 1, mpidr 80000102 CPU7: failed to come online Brought up 6 CPUs CPU: WARNING: CPU(s) started in wrong/inconsistent modes (primary CPU mode 0x13) CPU: This may indicate a broken bootloader or firmware.Thanks to a tip from Abhilash, this patch gets all 8 CPUs booting again, but the warning about CPUs started in inconsistent modes remains. Also, not being terribly familiar with Exynos internals, it's not at all obvious to me why this register write (done for *all* secondaries) makes things work works for the 2 secondary CPUs that didn't come online. It's also not obvious whether this is the right general fix, since it doesn't seem to be needed on other 542x or 5800 platforms.
I suspect the "right" fix is in the bootloader someplace, but not knowing this hardware well, I'm not sure if the fix is in u-boot proper, or somewhere in the binary blobs (bl1/bl2/tz) that start before u-boot. The u-boot I'm using is from the hardkernel u-boot repo[1], and I'd welcome any suggestions to try. I'm able to rebuild my own u-boot from there, but only have binaries for bl1/bl2/tz.
[1] branch "odroidxu3-v2012.07" of: https://github.com/hardkernel/u-boot.git
Cc: Mauro Ribeiro mauro.ribeiro@hardkernel.com Cc: Abhilash Kesavan a.kesavan@samsung.com, Cc: Andrew Bresticker abrestic@chromium.org Cc: Doug Anderson dianders@chromium.org Cc: Nicolas Pitre nicolas.pitre@linaro.org Signed-off-by: Kevin Hilman khilman@linaro.org
arch/arm/mach-exynos/mcpm-exynos.c | 2 ++ arch/arm/mach-exynos/regs-pmu.h | 1 + 2 files changed, 3 insertions(+)
Hi,
+Cc Marek, Bartlomiej, Kukjin Kim,
I would like to bring back this topic. Unfortunately I don't have access to source code of BL1 (or any other firmware blob) so my knowledge here comes mostly from experimenting and from looking at sources of vendor kernel for Gear 2 (Exynos3250) and SM-G900H (Galaxy S5, Exynos5422).
It seems that some booting firmware (I would suspect BL1 because this ships Samsung to Hardkernel) uses SPARE2 as synchronization mechanism. For example vendor kernel, when booting little core, it waits till SPARE2==1 and then executes software reset for this core.
Observations shown that BL1 for Odroid, when booting secondary little core:
- Expects that SPARE2 register will be initialized to 1.
- If it is, then it sets it to 0, proceeds further and little core boots.
- If it is not, then it sets it to 1 and waits. Maybe this is a
notification to userspace - reset me please!
Unfortunately executing software reset in that time (at point 3) stopped kernel from booting. No logs/dmesg and I was unable to turn on early printk.
The answer why two of little cores boot is quite simple now. At beginning the SPARE2==0 so first little core will set it to 1 and wait till software reset. Kernel timeouts on this CPU bring up so it starts the sequence for next little core. Now the SPARE2==1 so the core boots fine and SPARE2 is set to 0. The last little core starts from SPARE2==0, sets it to 1 and waits for software reset.
Since no one knows how this exactly works and we are stuck with BL1 provided as is, then IMHO the patch makes sense.
Kevin, can you refresh the patch? It would be nice to:
- set SPARE2 only for Odroid (of_machine_is_compatible()),
- extend the explanation.
Best regards, Krzysztof
I'm trying port the hardkernel's SPL to the mainline U-Boot at present. The mainline SPL is implemented for E5420 and E5800. But there are few differences: - different DRAM - different clocks - different boot core (peach-pi boots from A15) - bl2 signature - hdk's SPL uses smc calls ... and some more.
The BL1 keeps signature key and some part of code, but it's code is proprietary - but we should be able to setup the secondary cores in BL2.
When, I get the basic setup working, then I'm going to focus on the secondary CPU's init. I don't have the documentation for iROM code, so everything takes a while.
If you looking for the lowlevel code, which is executed after wakeup, please check this : https://github.com/hardkernel/u-boot/blob/odroidxu3-v2012.07/board/samsung/s...
The 'lowlevel_init' label is always executed on boot.
Best regards,