[PATCH v7 0/6] SMP and CPU hotplug support for Meson8/Meson8b

Wed Oct 25 14:05:09 PDT 2017

Hi Russel,

On Mon, Oct 23, 2017 at 11:49 AM, Russell King - ARM Linux
<linux at armlinux.org.uk> wrote:
> On Sat, Oct 21, 2017 at 12:14:28AM +0200, Martin Blumenstingl wrote:
>> Hi Russel,
>>
>> On Fri, Oct 6, 2017 at 11:30 PM, Kevin Hilman <khilman at baylibre.com> wrote:
>> > Martin Blumenstingl <martin.blumenstingl at googlemail.com> writes:
>> >
>> >> Hello Russel, Hi Kevin,
>> >>
>> >> On Sun, Sep 17, 2017 at 6:45 PM, Martin Blumenstingl
>> >> <martin.blumenstingl at googlemail.com> wrote:
>> >>> This patchset adds support for booting the secondary CPU cores (and
>> >>> taking them offline again) on Amlogic Meson8 and Meson8b SoCs.
>> >>> It is based on an earlier version from Carlo Caione - this helped me
>> >>> a lot to get a better understanding of how SMP/CPU hotplug works
>> >>> (compared to the code found in Amlogic's GPL kernel sources from
>> >>> year 2015).
>> >>>
>> >>> Changes since v6 from [6]:
>> >>> - rebased on top of v4.14-rc1 (which only corrected some line
>> >>>   numbers in the SCU patches)
>> >> it's been two weeks since v6 and since then Linus Lüssing has
>> >> confirmed that this works fine on his Odroid-C1 as well (many thanks
>> >> for testing!): [7]
>> >>
>> >>> Changes since v5 from [5]:
>> >>> - dropped dependency on another patch series (for the clock
>> >>>   controller's embedded reset controller, which is needed to boot
>> >>>   the secondary CPUs) from the cover-letter as that series is now
>> >>>   merged
>> >>> - fix incorrect documentation of scu_cpu_power_enable (thanks to
>> >>>   Russell King for spotting these). removed the paragraph about
>> >>>   preemption, cache coherency and interrupts as we're powering on
>> >>>   a CPU core (the text was copied from the original scu_power_mode
>> >>>   but simply not adjusted). also changed "Set the executing CPUs"
>> >>>   to "Set the given (logical) CPU's" as we're not modifying the
>> >>>   current CPU. this affects only patch #2
>> >>> - extended the commit message of patch #3 with a short sentence
>> >>>   about why SCU_CPU_STATUS_MASK was introduced
>> >>>
>> >>> Changes since v4 from [4]:
>> >>> - use __pa_symbol(secondary_startup) instead of
>> >>>   virt_to_phys(secondary_startup) as suggested by Florian Fainelli
>> >>>   (affects patch #4)
>> >>> - (cover-letter) removed dependency on my other patch
>> >>>   "ARM: dts: meson: add a node which describes the SRAM" [2] as that
>> >>>   was merged into Kevin's Amlogic repo today
>> >>> - dropped patch #5 ("clk: meson: meson8b: export the CPU soft reset
>> >>>   lines") again because the reset controller series exposes the
>> >>>   preprocessor macros now directly, see [1]
>> >>> - refreshed the .dts patches so they now include the new header for
>> >>>   the reset line preprocessor macros
>> >>>
>> >>> Changes since v3 from [3]:
>> >>> - added Rob's ACK to patch #1
>> >>> - replaced a msleep(10) with usleep_range(10000, 15000) in patch #4
>> >>> - removed all "pen" code from patch #4 as that code was not needed
>> >>>   at all (it was left-over while trying to fix Meson8 secondary CPU
>> >>>   boot - which turned out to have nothing to do with this "pen" code)
>> >>> - removed all memory barrier operations as they were added based on
>> >>>   the code in the Amlogic GPL kernel tree (while trying to fix the
>> >>>   Meson8 secondary CPU boot - just like the "pen" code). Everything
>> >>>   still works fine with these on my Meson8m2 and Meson8b boards.
>> >>> - added PATCH #5 as we now have to export the reset identifiers
>> >>>   (just like we do it with the clock identifiers / preprocessor
>> >>>   macros) - this is the result of a change in the reset controller
>> >>>   patch in version 2, see [1]
>> >>> - use the reset line preprocessor macros (from patch #5) in patches
>> >>>   #6 and #7
>> >>>
>> >>> Changes since v2 from [0]:
>> >>> - added support for Meson8 (which requires a slightly different
>> >>>   enable-method)
>> >>> - implemented CPU hotplug support which allows taking a CPU core
>> >>>   offline for both, Meson8 and Meson8b
>> >>> - add a function to smp_scu.c which allows enabling a CPU core from
>> >>>   a different CPU (previously only the power mode for the current CPU
>> >>>   could be changed). Without this the CPU cores on Meson8 won't come
>> >>>   up (Amlogic's vendor GPL kernel sources also enable power through
>> >>>   SCU as very first step for Meson8b as well)
>> >>> - add a function to smp_scu.c to get the power status of a CPU core
>> >>>   (which is needed because the code in .cpu_kill needs to wait until
>> >>>   the core is actually powered off)
>> >>> - dropped patch "ARM: DTS: meson8b: Extend L2 cache controller node"
>> >>>   as it is already applied (for both, Meson8 and Meson8b)
>> >>> - dropped the patches which implement the reset controller which is
>> >>>   built into the clock-controller, these are a separate series: [1]
>> >>> - moved the enable-method property to each CPU node
>> >>>
>> >>>
>> >>> [0] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-December/390355.html
>> >>> [1] http://lists.infradead.org/pipermail/linux-amlogic/2017-July/004456.html
>> >>> [2] http://lists.infradead.org/pipermail/linux-amlogic/2017-July/004282.html
>> >>> [3] http://lists.infradead.org/pipermail/linux-amlogic/2017-July/004297.html
>> >>> [4] http://lists.infradead.org/pipermail/linux-amlogic/2017-July/004354.html
>> >>> [5] http://lists.infradead.org/pipermail/linux-amlogic/2017-July/004460.html
>> >>> [6] http://lists.infradead.org/pipermail/linux-amlogic/2017-August/004588.html
>> >>>
>> >>> Carlo Caione (2):
>> >>>   dt-bindings: Amlogic: Add Meson8 and Meson8b SMP related documentation
>> >>>   ARM: dts: meson8b: add support for booting the secondary CPU cores
>> >>>
>> >>> Martin Blumenstingl (4):
>> >>>   ARM: smp_scu: add a helper for powering on a specific CPU
>> >>>   ARM: smp_scu: allow the platform code to read the SCU CPU status
>> could you please have a look at these two patches? it would be great
>> if you could give feedback on these, because they are needed for SMP
>> support on the Amlogic Meson8 and Meson8b platforms
>>
>> >>>   ARM: meson: Add SMP bringup code for Meson8 and Meson8b
>> >>>   ARM: dts: meson8: add support for booting the secondary CPU cores
>> >> @Russel: should Kevin take all patches including the two smp_scu ones?
>> >> or do you want to take them through your own tree?
>> >
>> > With Russell's ack, I can take the series via the amlogic tree.  But I'm
>> > also fine if Russell wants to take the arch/arm/* via his tree, and I
>> > will just queue up the DT.
>> please also let Kevin know if you would like him to take these patches
>> through the amlogic tree
>
> Stuff in this thread seems to be sent either over the weekend, or late
> on Friday, which means it gets buried by Monday.  I'll look at it now.
thank you for reviewing my patches!

I do this in my spare time - so I typically end up having all bugs
fixed at some point during the weekend
however, you still found my patches - problem solved. :)

Thank you!
Regards
Martin