On Fri, 2017-08-18 at 16:31 -0600, Prakash, Prashanth wrote: > Hi Rafael/Rui, > > On 8/17/2017 8:14 PM, Zhang Rui wrote: > > > > On Fri, 2017-08-18 at 02:09 +0200, Rafael J. Wysocki wrote: > > > > > > On Wed, Aug 9, 2017 at 4:27 PM, Zhang Rui <rui.zhang@xxxxxxxxx> > > > wrote: > > > > > > > > Hi, Prakash, > > > > > > > > On Tue, 2017-08-08 at 10:01 -0600, Prakash, Prashanth wrote: > > > > > > > > > > Hi Rui, > > > > > > > > > > On 8/8/2017 2:23 AM, Zhang Rui wrote: > > > > > > > > > > > > > > > > > > On Fri, 2017-07-14 at 11:48 -0600, Prashanth Prakash wrote: > > > > > > > > > > > > > > > > > > > > > Per ACPI 6.2 spec, platforms can optionally add a > > > > > > > string(_STR) > > > > > > > object within each thermal zone package which provides a > > > > > > > user > > > > > > > friendly name/description. > > > > > > > > > > > > > > Add support to parse the string object, which will be > > > > > > > exposed > > > > > > > to userspace by thermal framework. > > > > > > > > > > > > > is there any real request for this? > > > > > Yes, Qualcomm server platforms adds these description > > > > > strings. > > > > > > > > > > > > > > > > > > _STR is a generic control method for all the ACPI devices. > > > > > > Thus I'm wondering, if really needed, should we expose this > > > > > > in > > > > > > acpi > > > > > > bus > > > > > > instead? > > > > > AFAIK, adding a _STR to any package was not explicitly > > > > > allowed by > > > > > the > > > > > spec. > > > > > Updates in APCI 6.2 made it legal to add an _STR object to > > > > > thermal > > > > > zone > > > > > specifically, so added this support only to thermal zone. > > > > > > > > > I see that _STR is stated explicitly in 11.4.14, ACPI spec 6.2, > > > > but > > > > according to section 6.1.10, "The _STR object evaluates to a > > > > Unicode > > > > string that describes the device or thermal zone. " > > > > _STR is still a generic control method that can exist in any > > > > other > > > > device scope. > > > > > > > > so to me, this is a optional but generic feature for all the > > > > ACPI > > > > devices, and we don't have a solid reason that it should be > > > > part of > > > > thermal sysfs I/F, thus a better solution to me is to expose > > > > this > > > > as an > > > > attribute of ACPI device, and we can link to the ACPI device > > > > from > > > > thermal sysfs I/F in userspace. > > > > > > > > what do you think, Rafael? > > > Since you have a ->get_desc method, I don't have a big problem > > > with > > > the approach here. > > > > > > I'm not particularly liking the "<not supported>" thing returned > > > if > > > _STR is not present, though. > I will change the implementation such that if _STR object was not > found then > thermal_get_desc would return -ENXIO (or should it be different > errno?). > > > > > No, actually I mean adding a new sysfs attribute under ACPI device > > node, just like path/hid/status/adr, etc. > Sorry Rui, I didn't read your earlier comment correctly. Thermal > zone's _STR is > useful in couple of scenarios(even if ACPI device containing the > thermal_zone > had a _STR object): > - When we have more than 1 thermal sensors/zones under a device then > this will > allow us to differentiate them Yes I agree. >From userspace point of view, with you patch, userspace can get the content of _STR by cat /sys/class/thermal/thermal_zoneX/desc And what I mean is that, userspace can already get the same information by cat /sys/class/thermal/thermal_zoneX/device/description even without the patch. > - When we have some thermal sensors that doesn't have ACPI device > associated > with it. For example: a shared L3 cache, an abstract region on SoC. > In these cases > we can add a thermal zone object in an appropriate place in dsdt and > the > associated _STR will allow us to provide a user friendly > name/description. if the sensor is registered by native driver, I think .get_desc() is useful. But if you want to hack the dsdt to get it enumerated via ACPI, then my approach still works without the patch. :) thanks, rui > > > > Of course the attribute should be optional, depends on if the _STR > > control methods exist or not. > > > > thanks, > > rui > > > > > > Thanks, > > > Rafael > > -- > > To unsubscribe from this list: send the line "unsubscribe linux- > > acpi" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > Thanks for your feedback! > > -- > Regards, > Prashanth > > -- > To unsubscribe from this list: send the line "unsubscribe linux-acpi" > in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
