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From: Limonciello, M. <Mar...@de...> - 2020-08-21 20:43:49
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> -----Original Message----- > From: Mark Pearson <mar...@le...> > Sent: Friday, August 21, 2020 15:06 > To: Limonciello, Mario > Cc: ibm...@li...; pla...@vg...; > ibm...@hm...; bn...@re...; 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"? |
