RE: [External] RE: [PATCH v2] platform/x86: thinkpad_acpi: performance mode interface

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



> -----Original Message-----
> From: Mark Pearson <markpearson@xxxxxxxxxx>
> Sent: Friday, August 21, 2020 15:06
> To: Limonciello, Mario
> Cc: ibm-acpi-devel@xxxxxxxxxxxxxxxxxxxxx; platform-driver-x86@xxxxxxxxxxxxxxx;
> ibm-acpi@xxxxxxxxxx; bnocera@xxxxxxxxxx; Nitin Joshi
> Subject: Re: [External] RE: [PATCH v2] platform/x86: thinkpad_acpi:
> performance mode interface
> 
> 
> [EXTERNAL EMAIL]
> 
> On 8/21/2020 4:00 PM, Limonciello, Mario wrote:
> <snip>
> >>>> + +The sysfs entry provides the ability to return the current
> >>>> status and to set
> >>>> the +desired mode. For example:: + +        echo H >
> >>>> /sys/devices/platform/thinkpad_acpi/dytc_perfmode +        echo
> >>>> M > /sys/devices/platform/thinkpad_acpi/dytc_perfmode +
> >>>> echo L > /sys/devices/platform/thinkpad_acpi/dytc_perfmode +
> >>>
> >>> I was thinking about this some more, do you actually want another
> >>> mode that "disables"
> >>> this feature?   IE "O" turns it off an calls DYTC_DISABLE_CQL.
> >>>
> >>> For example if a user wanted to test the recently landed code in
> >>> thermald 2.3
> >>> and compare performance between the two it seems like this and
> >>> that "might" fight.
> >>> As an outsider looking in - I of course may be wrong too here.
> >>>
> >>> If at some point in the future thermald does a better job than
> >>> this implementation you
> >>> might also want an "out" to let thermald or another piece of
> >>> userland turn this off if it's in the picture.
> >>>
> >> I'm still digging into this one. Right now I haven't found a good
> >> clean way of just disabling the firmware. Currently when thermald
> >> goes in and tweaks the CPU power registers it has the effect of
> >> overriding the FW anyway - but I appreciate that's not quite the
> >> same as actually doing it explicitly.
> >>
> >
> > What about a modprobe parameter to disable at least?  That would at
> > least make it pretty easy to make a change, reboot and compare with
> > thermald (or other software) without disabling the rest of the
> > functionality of the thinkpad_acpi driver.
> >
> The problem is I don't have a good way to disable the firmware (that I
> know of yet) so a modprobe parameter wouldn't really do much. I guess it
> could skip providing the sysfs entry points - but the FW will still be
> there doing it's thing, so I'm not sure I see the benefit of that. At
> least the sysfs entry point gives a bit more insight into what is going on.
> Let me know if I'm missing something obvious.
> 

Oh so it's not actually the driver loading tells the firmware it's supposed
to work this way.  The firmware actually detects "I'm running on Linux, so I'll
do this differently"?






[Index of Archives]     [Linux Kernel Development]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux