On Wed, Mar 04, 2020 at 06:27:36PM +0100, Pavel Machek wrote: > On Tue 2020-03-03 18:43:51, Greg Kroah-Hartman wrote: > > From: Peter Chen <peter.chen@xxxxxxx> > > > > commit ca4b43c14cd88d28cfc6467d2fa075aad6818f1d upstream. > > > > To work properly on every architectures and compilers, the enum value > > needs to be specific numbers. > > All compilers are expected to handle this in the same way, as this is > in C standard. This patch is not neccessary, and should not be in mainline, > either. > > http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf > > 6.7.2.2 Enumeration specifiers > Syntax > ... > 3 The identifiers in an enumerator list are declared as constants that have type int and > may appear wherever such are permitted.107) An enumerator with = defines its > enumeration constant as the value of the constant expression. If the first enumerator has > no =, the value of its enumeration constant is 0. Each subsequent enumerator with no = > defines its enumeration constant as the value of the constant expression obtained by > adding 1 to the value of the previous enumeration constant. (The use of enumerators with > = may produce enumeration constants with values that duplicate other values in the same > enumeration.) The enumerators of an enumeration are also known as its members. > > Best regards, > Pavel > > > enum usb_charger_type { > > - UNKNOWN_TYPE, > > - SDP_TYPE, > > - DCP_TYPE, > > - CDP_TYPE, > > - ACA_TYPE, > > + UNKNOWN_TYPE = 0, > > + SDP_TYPE = 1, > > + DCP_TYPE = 2, > > + CDP_TYPE = 3, > > + ACA_TYPE = 4, > > }; It specified that we need to do this by the in-kernel documentation about how to write a solid api (which I can't find at the moment to point you at, sorry...) Also, you pointed at a draft C standard, is that really implemented by older compilers? thanks, greg k-h
