On Mon, Aug 24, 2015 at 2:29 PM, David Laight <David.Laight@xxxxxxxxxx> wrote: > From: Vaishali Thakkar [mailto:vthakkar1994@xxxxxxxxx] >> Sent: 22 August 2015 02:57 > ... >> >> - .bcdADC = __constant_cpu_to_le16(0x0100), >> >> - .wTotalLength = __constant_cpu_to_le16(UAC_DT_TOTAL_LENGTH), >> >> + .bcdADC = cpu_to_le16(0x0100), >> >> + .wTotalLength = cpu_to_le16(UAC_DT_TOTAL_LENGTH), >> > >> > Have you test compiled this on a big-endian system? >> > My gut feeling is that is fails. >> >> No. I have tested it on little-endian system only. But I'll >> be really surprised if this will fail. Can you please tell me >> if I am missing something in this particular case or same >> applies for other cases because most of the cases like >> __constant_<foo> are already converted to <foo>? >> >> As far as I know, if the argument is a constant the >> conversion happens at compile time. And unfolding both >> definitions returns to same expression. Still I am trying if >> someone can test it for me on big endian system. > > Flip one to cpu_to_be16() and see if it still compiles. Yes. It still compiles. > Static initialisers and case labels can be expressions, but the > expression itself must only contain constants. > So it needs to be constant regardless of the value of any constants. > If it contains 'a ? t : f' then both 't' and 'f' must be constant. > > In code, if 'a' is constant the optimiser discards one of 't' or 'f'. > I'm not sure what happens for non-static initialisers (they generate > odd code at the best of times). > > David > -- Vaishali -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
