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| Started by | Scott Wood <scottwood@freescale.com> |
|---|---|
| First post | 2015-08-06 05:00 +0200 |
| Last post | 2015-08-06 20:10 +0200 |
| Articles | 3 — 1 participant |
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Re: [PATCH 1/3] Powerpc: mpc85xx: refactor the PM operations Scott Wood <scottwood@freescale.com> - 2015-08-06 05:00 +0200
Re: [PATCH 1/3] Powerpc: mpc85xx: refactor the PM operations Scott Wood <scottwood@freescale.com> - 2015-08-06 07:50 +0200
Re: [PATCH 1/3] Powerpc: mpc85xx: refactor the PM operations Scott Wood <scottwood@freescale.com> - 2015-08-06 20:10 +0200
| From | Scott Wood <scottwood@freescale.com> |
|---|---|
| Date | 2015-08-06 05:00 +0200 |
| Subject | Re: [PATCH 1/3] Powerpc: mpc85xx: refactor the PM operations |
| Message-ID | <pUjzr-3Vy-11@gated-at.bofh.it> |
On Wed, 2015-08-05 at 18:11 +0800, Chenhui Zhao wrote: > On Tue, Aug 4, 2015 at 4:26 AM, Scott Wood <scottwood@freescale.com> > wrote: > > On Mon, 2015-08-03 at 19:32 +0800, Chenhui Zhao wrote: > > > > > > > > > On Sat, Aug 1, 2015 at 7:59 AM, Scott Wood <scottwood@freescale.com> > > > wrote: > > > > > > > > > > Could you explain irq_mask()? Why would there still be IRQs > > > destined > > > > for > > > > this CPU at this point? > > > > > > This function just masks irq by setting the registers in RCPM (for > > > example, RCPM_CPMIMR, RCPM_CPMCIMR). Actually, all irqs to this CPU > > > have been migrated to other CPUs. > > > > So why do we need to set those bits in RCPM? Is it just caution? > > Setting these bits can mask interrupts signalled to RCPM from MPIC as a > means of > waking up from a lower power state. So, cores will not be waked up > unexpectedly. Why would the MPIC be signalling those interrupts if they've been masked at the MPIC? -Scott -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Scott Wood <scottwood@freescale.com> |
|---|---|
| Date | 2015-08-06 07:50 +0200 |
| Message-ID | <pUmdY-86Q-19@gated-at.bofh.it> |
| In reply to | #1201403 |
On Thu, 2015-08-06 at 12:20 +0800, Chenhui Zhao wrote: > On Thu, Aug 6, 2015 at 10:57 AM, Scott Wood <scottwood@freescale.com> > wrote: > > On Wed, 2015-08-05 at 18:11 +0800, Chenhui Zhao wrote: > > > On Tue, Aug 4, 2015 at 4:26 AM, Scott Wood <scottwood@freescale.com> > > > wrote: > > > > On Mon, 2015-08-03 at 19:32 +0800, Chenhui Zhao wrote: > > > > > > > > > > > > > > > On Sat, Aug 1, 2015 at 7:59 AM, Scott Wood > > > <scottwood@freescale.com> > > > > > wrote: > > > > > > > > > > > > > > > > Could you explain irq_mask()? Why would there still be IRQs > > > > > destined > > > > > > for > > > > > > this CPU at this point? > > > > > > > > > > This function just masks irq by setting the registers in RCPM > > > (for > > > > > example, RCPM_CPMIMR, RCPM_CPMCIMR). Actually, all irqs to > > > this CPU > > > > > have been migrated to other CPUs. > > > > > > > > So why do we need to set those bits in RCPM? Is it just caution? > > > > > > Setting these bits can mask interrupts signalled to RCPM from MPIC > > > as a > > > means of > > > waking up from a lower power state. So, cores will not be waked up > > > unexpectedly. > > > > Why would the MPIC be signalling those interrupts if they've been > > masked at > > the MPIC? > > > > -Scott > > > > The interrupts to RCPM from MPIC are IRQ, Machine Check, NMI and > Critical interrupts. Some of them didn't be masked in MPIC. What interrupt could actually happen to a sleeping cpu that this protects against? -Scott -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Scott Wood <scottwood@freescale.com> |
|---|---|
| Date | 2015-08-06 20:10 +0200 |
| Message-ID | <pUxM5-8ij-9@gated-at.bofh.it> |
| In reply to | #1201445 |
On Thu, 2015-08-06 at 13:54 +0800, Chenhui Zhao wrote: > On Thu, Aug 6, 2015 at 1:46 PM, Scott Wood <scottwood@freescale.com> > wrote: > > On Thu, 2015-08-06 at 12:20 +0800, Chenhui Zhao wrote: > > > On Thu, Aug 6, 2015 at 10:57 AM, Scott Wood > > > <scottwood@freescale.com> > > > wrote: > > > > On Wed, 2015-08-05 at 18:11 +0800, Chenhui Zhao wrote: > > > > > On Tue, Aug 4, 2015 at 4:26 AM, Scott Wood > > > <scottwood@freescale.com> > > > > > wrote: > > > > > > On Mon, 2015-08-03 at 19:32 +0800, Chenhui Zhao wrote: > > > > > > > > > > > > > > > > > > > > > On Sat, Aug 1, 2015 at 7:59 AM, Scott Wood > > > > > <scottwood@freescale.com> > > > > > > > wrote: > > > > > > > > > > > > > > > > > > > > > > Could you explain irq_mask()? Why would there still be > > > IRQs > > > > > > > destined > > > > > > > > for > > > > > > > > this CPU at this point? > > > > > > > > > > > > > > This function just masks irq by setting the registers in > > > RCPM > > > > > (for > > > > > > > example, RCPM_CPMIMR, RCPM_CPMCIMR). Actually, all irqs to > > > > > this CPU > > > > > > > have been migrated to other CPUs. > > > > > > > > > > > > So why do we need to set those bits in RCPM? Is it just > > > caution? > > > > > > > > > > Setting these bits can mask interrupts signalled to RCPM from > > > MPIC > > > > > as a > > > > > means of > > > > > waking up from a lower power state. So, cores will not be > > > waked up > > > > > unexpectedly. > > > > > > > > Why would the MPIC be signalling those interrupts if they've been > > > > masked at > > > > the MPIC? > > > > > > > > -Scott > > > > > > > > > > The interrupts to RCPM from MPIC are IRQ, Machine Check, NMI and > > > Critical interrupts. Some of them didn't be masked in MPIC. > > > > What interrupt could actually happen to a sleeping cpu that this > > protects > > against? > > > > -Scott > > Not sure. Maybe spurious interrupts or hardware exceptions. Spurious interrupts happen due to race conditions. They don't happen because the MPIC is bored and decides to ring a CPU's doorbell and hide in the bushes. If by "hardware exceptions" you mean machine checks, how would such a machine check be generated by a core that is off? > However, setting them make sure dead cpus can not be waked up unexpectedly. I'm not seeing enough value here to warrant resurrecting the old sleep node stuff. -Scott -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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