On Fri, 2017-08-18 at 14:34 +0200, Rafael J. Wysocki wrote: > On Friday, August 18, 2017 4:14:47 AM CEST 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. > > No, actually I mean adding a new sysfs attribute under ACPI device > > node, just like path/hid/status/adr, etc. > Yes, I understood that, but since the power supply framework has a > description callback, why not to use it really? > I just checked the code, and ACPI devices indeed have 'description' sysfs attribute if there is _STR. Cool, that's what I'm proposing. But your statement, "the power supply framework has a description callback" still confuses me. > > > > Of course the attribute should be optional, depends on if the _STR > > control methods exist or not. > So what's the exact benefit from doing this over the approach the > $subject > patch? hmmm, the subject patch introduces kernel code to get _STR content from ACPI and then export it to userspace via a new thermal sysfs attribute. And what I'm proposing is that, if the content of _STR is available under ACPI device node, then we can easily get the information from thermal sysfs I/F using symbol links, thus we don't need kernel changes or new thermal sysfs attribute. 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
