On 06/30/2015 02:12 PM, Rafael J. Wysocki wrote: > Hi Al, > > On Fri, Jun 19, 2015 at 12:36 AM, Al Stone <al.stone@xxxxxxxxxx> wrote: >> Add the ACPI_SPEC_VERSION() macro to build a proper version number from >> a major and minor revision number. Add also the ACPI_FADT_SPEC_VERSION >> that constructs a proper version number from the entries in the current >> FADT. >> >> 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. >> >> Signed-off-by: Al Stone <al.stone@xxxxxxxxxx> >> --- >> include/linux/acpi.h | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/include/linux/acpi.h b/include/linux/acpi.h >> index a4acb55..33ed313 100644 >> --- a/include/linux/acpi.h >> +++ b/include/linux/acpi.h >> @@ -48,6 +48,11 @@ >> #include <acpi/acpi_io.h> >> #include <asm/acpi.h> >> >> +#define ACPI_SPEC_VERSION(major, minor) ((major<<8)|minor) > > One nit here. > > acpi_gbl_FADT.header.revision is of type u8 originally, so shifting it > by 8 bit positions only works due to some implicit type casting I > suppose. Bah. That was being sloppy on my part. Sorry about that. Will fix. > Moreover, it is not entirely clear why the macro is specific to the > computation of the ACPI spec version. As far as I know, that's the only way to extract the spec version from tables; I don't recall there being any other table with that info. Since I will likely use this again, it seemed to make sense at the time. > So I'd drop ACPI_SPEC_VERSION and only define ACPI_FADT_SPEC_VERSION > as something like > > #define ACPI_FADT_SPEC_VERSION (((unsigned > int)acpi_gbl_FADT.header.revision << 8) | (unsigned > int)acpi_gbl_FADT.minor_revision) > > Thanks, > Rafael > Sure. That makes sense. It makes it clearer that this is the version just from the FADT. I'll do that. -- ciao, al ----------------------------------- Al Stone Software Engineer Linaro Enterprise Group al.stone@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
