Re: [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@xxxxxxxxxx>

<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@xxxxxxxxxx>
+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@xxxxxxxxxx>
+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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