Messages in this thread | | | From | Patrice CHOTARD <> | Subject | Re: [PATCH 1/1] ARM: STi: Restore secondary CPU's bringup | Date | Wed, 19 Dec 2018 10:31:35 +0000 |
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Hi Russell
On 12/18/18 6:27 PM, Russell King - ARM Linux wrote: > On Tue, Dec 18, 2018 at 05:05:18PM +0000, Patrice CHOTARD wrote: >> Hi Russell >> >> On 12/18/18 4:52 PM, Russell King - ARM Linux wrote: >>> On Tue, Dec 18, 2018 at 03:48:13PM +0100, patrice.chotard@st.com wrote: >>>> From: Patrice Chotard <patrice.chotard@st.com> >>>> >>>> Due to pen_release and boot_lock removal, secondary CPU's bringup >>>> was broken. Restore CPU's bringup by reworking properly >>>> .smp_prepare_cpus and .smp_boot_secondary STi callbacks. >>> >>> Sorry, maybe I don't understand your commit message, but you seem to be >>> saying that removal of the pen_release and boot_lock broke STi's secondary >>> CPU bring up? Please clarify, and explain how that happened. >> >> Correct, CPU1 failed to come online. >> >> It seems that writing secondary_startup address at cpu-release-addr in >> .smp_prepare_cpus callback was too early. >> >> Doing it in .smp_boot_secondary callback, insures that secondary_data >> struct is populated in __cpu_up() (stack, pgdir and swapper_pg_dir fields). > > Ah, you're saying that it causes the CPU to jump to secondary_startup > while the boot CPU is in smp_prepare_cpus()? What triggers the CPU
Yes
> to jump to the address written to cpu_strt_ptr? What you're saying > seems to suggest that it's the write to that address, rather than the > IPI that's sent in sti_boot_secondary().
At platform startup, an U-Bootrom firmware initialize secondary CPU and make it spinning waiting for a jump address to be written at cpu_strt_ptr.
I didn't pay attention to the IPI, you are right IPI is useless, i will remove it.
> > If the IPI in sti_boot_secondary() isn't doing anything, it ought to > be removed. It'd also be a good idea to document what's going on as > comments in the code for future maintanence.
Agree, i will add a comment.
Thanks
Patrice
> >> If you are ok, i will pick up your patch [1] and this one to prepare a >> STi pull-request. > > Yes, although I'll have to delay patch 9 as a result. > | |