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SubjectRe: [External] Re: [PATCH] [RFC] Documentation: Add documentation for new platform_profile sysfs attribute
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Thanks Hans

On 26/10/2020 14:33, Hans de Goede wrote:
> Hi Mark,
>
> Thank you for this new version.
>
> On 10/26/20 6:44 PM, Mark Pearson wrote:
>> From: Hans de Goede <hdegoede@redhat.com>
>>
<snip>

>> +
>> +If for some reason there is no good match when mapping then a new profile-name
>> +may be added. Drivers which wish to introduce new profile-names must:
>> +1. Have very good reasons to do so.
>> +2. Add the new profile-name to this document, so that future drivers which also
>> + have a similar problem can use the same new.
>
> s/same new/same name/
I've read this document so many times...I'm not sure how I missed that
one. Thanks.
>
>> + Usually new profile-names will
>> + be added to the "extra profile-names" section of this document. But in some
>> + cases the set of standard profile-names may be extended.
>
> With the change from a more generic API to this new one more targeted towards DPTF
> I would drop this part.
OK - I have some questions then related to this change, below
>
>
>> +
>> +What: /sys/firmware/acpi/platform_profile_choices
>> +Date: October 2020
>> +Contact: Hans de Goede <hdegoede@redhat.com>
>> +Description:
>> + Reading this file gives a space separated list of profiles
>> + supported for this device.
>> +
>> + Drivers must use the following standard profile-names whenever
>> + possible:
>> +
>> + low-power: Emphasises low power consumption
>> + quiet: Offers quieter operation (lower fan
>> + speed but with higher performance and
>> + temperatures then seen in low-power
>
> I think the description here is a bit too specific, this may cause userspace
> to have expectations which are not necessary true. I would describe this as
> just:
>
> quiet: Emphasises quieter operation
>
Agreed. I'll update

>> + balanced: Balance between low power consumption
>> + and performance
>> + performance: Emphasises performance (and may lead to
>> + higher temperatures and fan speeds)
>> +
>> + Userspace may expect drivers to offer at least several of these
>> + standard profile-names! If none of the above are a good match
>> + for some of the drivers profiles, then drivers may use one of
>> + these extra profile-names:
>> + <reserved for future use>
>> +
If we remove the extra profile-names section above then I think it
should be removed here too. If someone wants to add a new 'mode' then it
would be added to the list of 'standard names', and becomes a new
option. Wanted to check I'm not missing something important.

>> +What: /sys/firmware/acpi/platform_profile
>> +Date: October 2020
>> +Contact: Hans de Goede <hdegoede@redhat.com>
>> +Description:
>> + Reading this file gives the current selected profile for this
>> + device. Writing this file with one of the strings from
>> + available_profiles changes the profile to the new value.
>
> The part about custom profiles below may be dropped. That was intended for use
> with e.g. GPUs but since this now strictly is a system-level profile API, the
> part below can be dropped now.
Agreed
>
>
>> +
>> + Reading this file may also return "custom". This is intended for
>> + drivers which have and export multiple knobs. Such drivers may
>> + very well still want to offer a set of profiles for easy of use
>> + and to be able to offer a consistent standard API (this API) to
>> + userspace for configuring their performance. The "custom" value
>> + is intended for when ai user has directly configured the knobs
>> + (through e.g. some advanced control-panel for a GPU) and the
>> + knob values do not match any of the presets represented by the
>> + platform-profiles. In this case writing this file will
>> + override the modifications and restore the selected presets.
>> +
>>
>
> Regards,
>
> Hans
>
Thanks!
mark

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