From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: multipart/mixed; boundary="===============0772970023074584878==" MIME-Version: 1.0 From: Al Stone Subject: Re: [Devel] GPE blocks in reduced hardware mode Date: Thu, 05 Dec 2013 09:23:51 -0700 Message-ID: <52A0A897.4000905@redhat.com> In-Reply-To: 94F2FBAB4432B54E8AACC7DFDE6C92E37C7A634E@ORSMSX103.amr.corp.intel.com List-ID: To: devel@acpica.org --===============0772970023074584878== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable On 12/04/2013 08:51 AM, Moore, Robert wrote: > Some text pulled from the ACPI 5.0 Spec: > > > 5.6 ACPI Event Programming Model > The ACPI event programming model is based on the SCI interrupt and Genera= l-Purpose Event (GPE) register. ACPI provides an extensible method to raise= and handle the SCI interrupt, as described in this section. > Hardware-reduced ACPI platforms (Section 4.1) use GPIO Interrupt Connecti= ons to signal ACPI Events, described in Section 5.6.5. > > > 5.6.1 ACPI Event Programming Model Components > The components of the ACPI event programming model are the following: > * OSPM > * FADT > * PM1a_STS, PM1b_STS and PM1a_EN, PM1b_EN fixed register blocks > * GPE0_BLK and GPE1_BLK register blocks > * GPE register blocks defined in GPE block devices > > > 5.6.5 GPIO-signaled ACPI Events > On Hardware-reduced ACPI platforms, ACPI events are signaled when a GPIO = Interrupt is received by OSPM, > > > 7.2.13 PRW (Power Resources for Wake) > For HW-Reduced ACPI platforms, the GpeInfo structure is ignored by OSPM. > > >>> Hardware-reduced ACPI platforms (Section 4.1) use GPIO Interrupt Connec= tions to signal ACPI Events. > > I think this sentence says that on hardware-reduced ACPI platforms, there= are no GPEs, period. > Bob Thanks for the pointers; I'm afraid I can't add anything to that list -- it matches what I came up with when I scanned again last night. I agree with you that the spec is saying are no GPEs in hardware reduced, but I think it is implied, versus it being stated explicitly. And that's where I get a bit puzzled. I'll take this up with the ASWG and see if I can get some sort of unambiguous wording added in. >> -----Original Message----- >> From: Devel [mailto:devel-bounces(a)acpica.org] On Behalf Of Moore, Robe= rt >> Sent: Tuesday, December 03, 2013 10:28 PM >> To: Al Stone; devel(a)acpica.org >> Subject: Re: [Devel] GPE blocks in reduced hardware mode >> >> >> >>> -----Original Message----- >>> From: Al Stone [mailto:ahs3(a)redhat.com] >>> Sent: Tuesday, December 03, 2013 5:39 PM >>> To: Moore, Robert; devel(a)acpica.org >>> Subject: Re: [Devel] GPE blocks in reduced hardware mode >>> >>> On 12/03/2013 05:18 PM, Moore, Robert wrote: >>>> The first thing is that there are no GPE block devices in the field, >>> never have been. I don't think ACPICA actually supports them fully. It >>> is a bit of an "orphan" feature of ACPI. >>> >>> I see. Yeah, I did find GPE block device support confusing in the code. >>> It seems like the infrastructure to handle them is present, but there >>> is no code to handle the "ACPI0006" ID anywhere I can find (that may >>> be a Linux limitation, though). >> >> >> Correct. There needs to be a linux driver that is loaded upon detection = of >> an _HID of ACPI0006. This does not exist. Thus, there is no support for >> this feature in Linux. >> >> The GPE block device was a bit of a fantasy that never materialized in a= ny >> hardware that I know of. And one could certainly conclude with some high >> degree of probability that nobody is going to implement custom hardware = to >> support a GPE block device on a (ahem) "hardware reduced platform". >> >> Bob >> >> >> >> >>> >>>> I'll have to take a look closer at the spec for an exact reference, >>>> but >>> basically one of the things that ACPI_REDUCED_HARDWARE means is no >>> GPEs, IIRC. >>> >>> Right -- that's what ACPI_REDUCED_HARDWARE means in the ACPICA code; >>> that seems pretty clear. I just can't seem to find anything that >>> clear in the spec :/... >>> >>> I'll continue to look in the spec but if you find something before I >>> do, do let me know. >>> >>> Thanks! >>> >>>>> -----Original Message----- >>>>> From: Devel [mailto:devel-bounces(a)acpica.org] On Behalf Of Al Stone >>>>> Sent: Tuesday, December 03, 2013 2:38 PM >>>>> To: devel(a)acpica.org >>>>> Subject: [Devel] GPE blocks in reduced hardware mode >>>>> >>>>> Howdy. >>>>> >>>>> I've been trying to do some clean-up on the Linux ACPI driver with >>>>> regard to the reduced hardware profile introduced in ACPI 5.0. >>>>> >>>>> In thinking about GPE block devices, I was looking through the >>>>> functions in source/components/events/evxfgpe.c and noticed that >>>>> they are all #ifdef'd out for ACPI_REDUCED_HARDWARE. When I look >>>>> back through the specification, however, I cannot find any place >>>>> where they >>> are prohibited. >>>>> >>>>> Clearly, the gpe0/1 blocks in the FADT are not to be used; this is >>>>> explicitly stated in section 5.2.9 of the spec. Could someone >>>>> please point me to a similar statement for a GPE block device? I >>>>> just cannot seem to find it. >>>>> >>>>> The closest thing I can find is section 9.10 implying that a GPE >>>>> block device is an extension of the gpe0/1 blocks from the FADT, >>>>> but there is no explicit statement there so it is ambiguous to me. >>>>> >>>>> Thanks in advance for any pointers; I'm just puzzled at this point >>>>> and trying to understand how the conclusion came to be. >>>>> >>>>> -- >>>>> ciao, >>>>> al >>>>> ----------------------------------- >>>>> Al Stone >>>>> Software Engineer >>>>> Red Hat, Inc. >>>>> ahs3(a)redhat.com >>>>> ----------------------------------- >>>>> _______________________________________________ >>>>> Devel mailing list >>>>> Devel(a)acpica.org >>>>> https://lists.acpica.org/mailman/listinfo/devel >>> >>> >>> -- >>> ciao, >>> al >>> ----------------------------------- >>> Al Stone >>> Software Engineer >>> Red Hat, Inc. >>> ahs3(a)redhat.com >>> ----------------------------------- >> _______________________________________________ >> Devel mailing list >> Devel(a)acpica.org >> https://lists.acpica.org/mailman/listinfo/devel -- = ciao, al ----------------------------------- Al Stone Software Engineer Red Hat, Inc. ahs3(a)redhat.com ----------------------------------- --===============0772970023074584878==--