On Wed, Mar 10, 2021 at 01:33:24AM +0000, Chen, Mike Ximing wrote: > > > -----Original Message----- > > From: Greg KH <gre...@linuxfoundation.org> > > > > On Wed, Feb 10, 2021 at 11:54:06AM -0600, Mike Ximing Chen wrote: > > > + > > > +#include "dlb_bitmap.h" > > > + > > > +#define BITS_SET(x, val, mask) (x = ((x) & ~(mask)) \ > > > + | (((val) << (mask##_LOC)) & (mask))) > > > +#define BITS_GET(x, mask) (((x) & (mask)) >> (mask##_LOC)) > > > > Why not use the built-in kernel functions for this? Why are you > > creating your own? > > > FIELD_GET(_mask, _val) and FIELD_PREP(_mask, _val) in include/linux/bitfield.h > are similar to our BITS_GET() and BITS_SET(). However in our case, mask##_LOC > is a known constant defined in dlb_regs.h, so we don't need to use > _buildin_ffs(mask) to calculate the location of mask as FIELD_GET() and > FIELD_PREP() > do. We can still use FIELD_GET and FIELD_PREP, but our macros are a little > more > efficient. Would it be OK to keep them?
No, please use the kernel-wide proper functions, there's no need for single tiny driver to be "special" in this regard. If somehow the in-kernel functions are not sufficient, it's always better to fix them up than to go your own way here. thanks, greg k-h
