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Why we put FAN to full speed in its suspend callback

DISCUSSION Aaron Lu 2 participants 3 messages Jan 22, 2014 – Jan 23, 2014 ACPI

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Aaron Lu

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Hi,

I was trying to minimize system suspend time and it turned out there are firmwares that would do crazy things like delaying 10ms in FAN's power on control method. So I wonder why do we want to put the FAN into ACPI D0 state when we are going to enter a sleep state? The code seems to be written according to Pavel's comment here:
https://bugzilla.kernel.org/show_bug.cgi?id=5000#c6
It would be great to understand why and remove that operation if possible, thanks for reading and taking your time bringing back your ancient memory :-)

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Quoted 1 line · Aaron Lu

Hi,

Hi,

Quoted 9 lines

I was trying to minimize system suspend time and it turned out there are firmwares that would do crazy things like delaying 10ms in FAN's power on control method. So I wonder why do we want to put the FAN into ACPI D0 state when we are going to enter a sleep state? The code seems to be written according to Pavel's comment here:
https://bugzilla.kernel.org/show_bug.cgi?id=5000#c6
It would be great to understand why and remove that operation if possible, thanks for reading and taking your time bringing back your ancient memory :-)

Yes, this is for image creation code during hibernation and the same set of callbacks was used for hibernation and suspend at that time. I think we can remove that thing for system suspend and leave it for hibernation only.

Thanks!

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I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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Removed Konstantin since his email address is undeliverable.

Quoted 15 lines · Rafael J. Wysocki
Quoted 1 line · Aaron Lu

Hi,

Hi,

Quoted 9 lines

I was trying to minimize system suspend time and it turned out there are firmwares that would do crazy things like delaying 10ms in FAN's power on control method. So I wonder why do we want to put the FAN into ACPI D0 state when we are going to enter a sleep state? The code seems to be written according to Pavel's comment here:
https://bugzilla.kernel.org/show_bug.cgi?id=5000#c6
It would be great to understand why and remove that operation if possible, thanks for reading and taking your time bringing back your ancient memory :-)

Quoted 3 lines

Yes, this is for image creation code during hibernation and the same set of callbacks was used for hibernation and suspend at that time. I think we can remove that thing for system suspend and leave it for hibernation only.

OK, thanks a lot for the clarification, I'll prepare a patch to do that.