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Message-ID: <BYAPR11MB30959EDCE4CAED3834982CD2D9919@BYAPR11MB3095.namprd11.prod.outlook.com>
Date: Wed, 10 Mar 2021 20:26:02 +0000
From: "Chen, Mike Ximing" <mike.ximing.chen@...el.com>
To: Greg KH <gregkh@...uxfoundation.org>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"davem@...emloft.net" <davem@...emloft.net>,
"kuba@...nel.org" <kuba@...nel.org>,
"arnd@...db.de" <arnd@...db.de>,
"Williams, Dan J" <dan.j.williams@...el.com>,
"pierre-louis.bossart@...ux.intel.com"
<pierre-louis.bossart@...ux.intel.com>
Subject: RE: [PATCH v10 03/20] dlb: add resource and device initialization
> -----Original Message-----
> From: Greg KH <gregkh@...uxfoundation.org>
> Sent: Wednesday, March 10, 2021 3:13 AM
> To: Chen, Mike Ximing <mike.ximing.chen@...el.com>
> Cc: netdev@...r.kernel.org; davem@...emloft.net; kuba@...nel.org;
> arnd@...db.de; Williams, Dan J <dan.j.williams@...el.com>; pierre-
> louis.bossart@...ux.intel.com; Gage Eads <gage.eads@...el.com>
> Subject: Re: [PATCH v10 03/20] dlb: add resource and device initialization
>
> On Wed, Mar 10, 2021 at 01:33:24AM +0000, Chen, Mike Ximing wrote:
> >
> > > -----Original Message-----
> > > From: Greg KH <gregkh@...uxfoundation.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.
>
OK. I will use FIELD_GET() and FIELD_PREP() macros in the next revision.
Thanks
Mike
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