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.stone@xxxxxxxxxx> >>>>> --- >>>>> 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. 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. -- ciao, al ----------------------------------- Al Stone Software Engineer Red Hat, Inc. ahs3@xxxxxxxxxx ----------------------------------- -- 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
