lkml.org 
[lkml]   [2014]   [Jan]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v4 2/5] arm: add new asm macro update_sctlr
On Wed, Jan 22, 2014 at 11:20:55AM +0000, Will Deacon wrote:
> > +#ifdef CONFIG_CPU_CP15
> > +/* Macro for setting/clearing bits in sctlr */
> > + .macro update_sctlr, set:req, clear:req, tmp:req, tmp2:req
> > + mrc p15, 0, \tmp, c1, c0, 0
> > + ldr \tmp2, =\set
> > + orr \tmp, \tmp, \tmp2
> > + ldr \tmp2, =\clear
> > + mvn \tmp2, \tmp2
> > + and \tmp, \tmp, \tmp2
> > + mcr p15, 0, \tmp, c1, c0, 0
>
> I think this would be cleaner if you force the caller to put set and clear
> into registers beforehand, rather than have to do the literal load every
> time. Also, I don't think set and clear should be required (and then you can
> lose tmp2 as well).

I can't figure out how to make register-parameters non-required
(i.e. conditionalise on whether an optional parameter was provided),
so my attempt of refactoring actually ends up using an additional
register:

#ifdef CONFIG_CPU_CP15
/* Macro for setting/clearing bits in sctlr */
.macro update_sctlr, set:req, clear:req, tmp:req
mrc p15, 0, \tmp, c1, c0, 0
orr \tmp, \set
mvn \clear, \clear
and \tmp, \tmp, \clear
mcr p15, 0, \tmp, c1, c0, 0
.endm
#endif

If you think that's an improvement I can do that, and I have (just)
enough registers to spare.
If I'm being daft with my macro issues, do point it out.

/
Leif


\
 
 \ /
  Last update: 2014-01-29 20:01    [W:0.357 / U:0.024 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site