On Monday, July 06, 2015 03:53:14 PM Al Stone wrote: > On 07/03/2015 05:50 PM, Rafael J. Wysocki wrote: > > On Friday, July 03, 2015 01:22:13 PM Al Stone wrote: > >> On 07/02/2015 11:23 PM, Hanjun Guo wrote: > >>> Hi Rafael, > >>> > >>> On 2015/7/3 8:21, Rafael J. Wysocki wrote: > >>>> On Thursday, July 02, 2015 05:48:34 PM Al Stone wrote: > >>>>> Add the __ACPI_FADT_SPEC_VERSION() helper macro to build a proper > >>>>> version > >>>>> number from a major and minor revision number. Add also macros that use > >>>>> the helper to construct the current version from the values in the FADT > >>>>> (i.e., ACPI_FADT_SPEC_VERSION) and both the 5.1 and 6.0 versions. > >>>>> > >>>>> These macros are added in order to simplify retrieving and comparing > >>>>> ACPI > >>>>> specification version numbers, since this is becoming a more frequent > >>>>> need. > >>>>> In particular, there are some architectures that require at least a > >>>>> certain > >>>>> version of the spec, and there are differences in some structure sizes > >>>>> that > >>>>> have changed with recent versions but can only be tracked by spec > >>>>> version > >>>>> number. > >>>>> > >>>>> Fixes: aeb823bbacc2 (ACPICA: ACPI 6.0: Add changes for FADT table.) > >>>>> Signed-off-by: Al Stone <al.st...@linaro.org> > >>>>> --- > >>>>> include/linux/acpi.h | 10 ++++++++++ > >>>>> 1 file changed, 10 insertions(+) > >>>>> > >>>>> diff --git a/include/linux/acpi.h b/include/linux/acpi.h > >>>>> index c471dfc..0e525e8 100644 > >>>>> --- a/include/linux/acpi.h > >>>>> +++ b/include/linux/acpi.h > >>>>> @@ -48,6 +48,16 @@ > >>>>> #include <acpi/acpi_io.h> > >>>>> #include <asm/acpi.h> > >>>>> > >>>>> +#define __ACPI_FADT_SPEC_VERSION(major, minor) \ > >>>>> + ((unsigned int)major << 8 | (unsigned int)minor) > >>>>> + > >>>>> +#define ACPI_FADT_SPEC_VERSION \ > >>>>> + __ACPI_FADT_SPEC_VERSION(acpi_gbl_FADT.header.revision, \ > >>>>> + acpi_gbl_FADT.minor_revision) > >>>>> + > >>>>> +#define ACPI_FADT_SPEC_VERSION_51 __ACPI_FADT_SPEC_VERSION(5, 1) > >>>>> +#define ACPI_FADT_SPEC_VERSION_60 __ACPI_FADT_SPEC_VERSION(6, 0) > >>>> I'd add underscores here, eg. ACPI_FADT_SPEC_VERSION_6_0 > >>> > >>> Agreed. > >> > >> Will do. This was a flip of the coin, on my part. > >> > >>>> And what if there is 5.2 or even 5.3? > >>> > >>> Hmm, do you mean in the future or just now? for both two cases, > >>> only 5.1 and 5.1 errata (still has the same ACPI version with 5.1) > >>> will be available, then jump to 6.0 and going forward if new versions > >>> in the future. > >>> > >>> I'm not sure if I understand your question correctly, if > >>> not, please correct me :) > >>> > >>> Thanks > >>> Hanjun > >> > >> I'm not sure I understand the question, either. Traditionally, the > >> spec versioning has been exclusively linear -- i.e., now that 6.0 > >> has replaced 5.1, there will be no more 5.x. There may be errata > >> published (e.g., there was a 5.1A, and a 6.0A is forthcoming) but > >> the errata are not encoded in tables anywhere since they are meant > >> only as corrections to the base version. This is unlikely to change, > >> but not impossible, of course :). > >> > >> The only reason for putting in macros for 5.1 and 6.0 is that those > >> are the versions that I'm concerned with for this particular fix and > >> I know I will use them. If others are needed, I'd have those that > >> need them add them. > > > > It seems to me that you only need to compare acpi_gbl_FADT.header.revision > > with 6 for this fix, though (if less than 6, use the old way, or use the > > new way otherwise). > > > > Isn't that the case? > > > > Rafael > > > > Ah, sorry for being a bit dense. Yes, on arm64 we only support 5.1 or > later so for now, less than 6 is a sufficient test. The 5.0 spec defines > yet a third size for the GICC subtable with the same MADT version number > (40 bytes) but we won't initialize ACPI if we have anything before 5.1.
OK > So, I could take this patch out of the set and reduce patch 2/3 somewhat > by just comparing against acpi_gbl_FADT.header.revision. I think that's > what I'll do unless you think these macros have intrinsic value for other > reasons. That would be fine by me, so please do it. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
