Re: 答复: [PATCH v4 20/28] ARM: owl: Implement CPU enable-method for S500

From	Andreas Färber <afaerber@suse.de>
Newsgroups	linux.kernel
Subject	Re: 答复: [PATCH v4 20/28] ARM: owl: Implement CPU enable-method for S500
Date	2017-07-01 22:00 +0200
Message-ID	<tYwIG-7BU-5@gated-at.bofh.it> (permalink)
References	(1 earlier) <tPb0J-1BU-5@gated-at.bofh.it> <tUJ1M-3E2-27@gated-at.bofh.it> <tXJeW-IJ-21@gated-at.bofh.it> <tXJyj-P8-37@gated-at.bofh.it> <tYiFI-6Cs-3@gated-at.bofh.it>
Organization	SUSE Linux GmbH

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Hi David,

Am 01.07.2017 um 06:42 schrieb 刘炜:
> OWL_CPUx_ADDR is the physical address of CPUx wakeup function.
> OWL_CPUx_FLAG is a valid flag of OWL_CPUx_ADDR. 
> 
> After CPUxs are wakeuped by SEV instruction, they will check their own OWL_CPUx_FLAG register. If the register vlaue is 0x55aa, CPUx will jump to OWL_CPUx_ADDR to boot up, otherwize go to sleep by WFE.
> 
> So the pen release staff is not necessary, you can remove these code safely.

Thank you for the quick confirmation!

I have just tested a patch, and it appears to work.

Is owl_v7_invalidate_l1 necessary? mach-sunxi (that Arnd pointed to as
example) uses secondary_startup directly, without custom assembler code.

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/arch/arm/mach-actions/headsmp.S

> BTW: CPU2/3 must exit the power gate state before wakeup, and CPU1 is always power on and has no power gate control.

Yes, the S500 SPS was luckily documented in the manual. The power-gating
for CPU2/3 is already implemented:

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/arch/arm/mach-actions/platsmp.c

For S900 however SPS is sadly not documented... If you know who at
Actions Semi could help there, please also take a look at:
https://github.com/96boards/documentation/issues/59

Best regards,

Andreas

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Thread

Re: [PATCH v4 20/28] ARM: owl: Implement CPU enable-method for S500 Arnd Bergmann <arnd@arndb.de> - 2017-06-21 10:20 +0200
  Re: [PATCH v4 20/28] ARM: owl: Implement CPU enable-method for S500 Arnd Bergmann <arnd@arndb.de> - 2017-06-21 12:30 +0200
    Re: [PATCH v4 20/28] ARM: owl: Implement CPU enable-method for S500 Andreas Färber <afaerber@suse.de> - 2017-06-21 18:50 +0200
      Re: [PATCH v4 20/28] ARM: owl: Implement CPU enable-method for S500 Arnd Bergmann <arnd@arndb.de> - 2017-06-21 20:10 +0200
  Re: [PATCH v4 20/28] ARM: owl: Implement CPU enable-method for S500 Arnd Bergmann <arnd@arndb.de> - 2017-06-29 17:10 +0200
    Re: [PATCH v4 20/28] ARM: owl: Implement CPU enable-method for S500 Andreas Färber <afaerber@suse.de> - 2017-06-29 17:30 +0200
      Re: [PATCH v4 20/28] ARM: owl: Implement CPU enable-method for S500 Arnd Bergmann <arnd@arndb.de> - 2017-06-29 18:00 +0200
        [PATCH] ARM: owl: smp: Drop bogus holding pen Andreas Färber <afaerber@suse.de> - 2017-07-01 23:40 +0200
          Re: [PATCH] ARM: owl: smp: Drop bogus holding pen Arnd Bergmann <arnd@arndb.de> - 2017-07-03 14:40 +0200
      答复: [PATCH v4 20/28] ARM: owl: Implement CPU enable-method for S500 刘炜 <liuwei@actions-semi.com> - 2017-07-01 07:00 +0200
        Re: 答复: [PATCH v4 20/28] ARM: owl: Implement CPU enable-method for S500 Andreas Färber <afaerber@suse.de> - 2017-07-01 22:00 +0200
          RE: RE: [PATCH v4 20/28] ARM: owl: Implement CPU enable-method for S500 刘炜 <liuwei@actions-semi.com> - 2017-07-03 10:20 +0200

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