linux-kernel - RE: [PATCH] drm/amd/powerplay: use ARRAY

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Date:	Fri, 13 May 2016 17:23:22 +0000
From:	"Deucher, Alexander" <Alexander.Deucher@....com>
To:	'Muhammad Falak R Wani' <falakreyaz@...il.com>,
	Jani Nikula <jani.nikula@...ux.intel.com>
CC:	"Koenig, Christian" <Christian.Koenig@....com>,
	Nils Wallménius <nils.wallmenius@...il.com>,
	"Zhou, Jammy" <Jammy.Zhou@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	"Zhu, Rex" <Rex.Zhu@....com>,
	"Dan Carpenter" <dan.carpenter@...cle.com>
Subject: RE: [PATCH] drm/amd/powerplay: use ARRAY_SIZE() for size of array

> -----Original Message-----
> From: Muhammad Falak R Wani [mailto:falakreyaz@...il.com]
> Sent: Friday, May 13, 2016 1:17 PM
> To: Jani Nikula
> Cc: Koenig, Christian; Nils Wallménius; Zhou, Jammy; linux-
> kernel@...r.kernel.org; dri-devel@...ts.freedesktop.org; Deucher,
> Alexander; Zhu, Rex; Dan Carpenter
> Subject: Re: [PATCH] drm/amd/powerplay: use ARRAY_SIZE() for size of
> array
> 
> On Thu, May 12, 2016 at 12:53:48PM +0300, Jani Nikula wrote:
> > On Wed, 11 May 2016, Muhammad Falak R Wani <falakreyaz@...il.com>
> wrote:
> > > Use ARRAY_SIZE() for the size calculation of the array. Also move the
> > > condition evaulation function out of the for loop.
> > > Although, any respectable c-compiler would optimize this and evaluate
> > > the function only once outside the loop, but the optimzation engine
> > > of gcc is bit brain-dead, and at times needs some hand holding.
> >
> > This just caught my eye. ARRAY_SIZE is a macro that expands to a compile
> > time constant. Arguably adding the the local variable here gives GCC
> > more chances to go wrong than keeping the ARRAY_SIZE in the loop
> > condition.
> >
> > BR,
> > Jani.
> >
> > >
> > > Signed-off-by: Muhammad Falak R Wani <falakreyaz@...il.com>
> > > ---
> > >  drivers/gpu/drm/amd/powerplay/smumgr/cz_smumgr.c | 3 ++-
> > >  1 file changed, 2 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/amd/powerplay/smumgr/cz_smumgr.c
> b/drivers/gpu/drm/amd/powerplay/smumgr/cz_smumgr.c
> > > index da18f44..718a551 100644
> > > --- a/drivers/gpu/drm/amd/powerplay/smumgr/cz_smumgr.c
> > > +++ b/drivers/gpu/drm/amd/powerplay/smumgr/cz_smumgr.c
> > > @@ -636,10 +636,11 @@ static int
> cz_smu_populate_firmware_entries(struct pp_smumgr *smumgr)
> > >  	int ret;
> > >  	enum cgs_ucode_id ucode_id;
> > >  	struct cgs_firmware_info info = {0};
> > > +	int n = ARRAY_SIZE(firmware_list);
> > >
> > >  	cz_smu->driver_buffer_length = 0;
> > >
> > > -	for (i = 0; i < sizeof(firmware_list)/sizeof(*firmware_list); i++) {
> > > +	for (i = 0; i < n; i++) {
> > >
> > >  		firmware_type =
> cz_translate_firmware_enum_to_arg(smumgr,
> > >  					firmware_list[i]);
> >
> > --
> > Jani Nikula, Intel Open Source Technology Center
> Should i send a new patch, with these modifications. Sorry for my
> childish mistake, i got a little too carried away.

Yes, please send an updated patch.

Thanks,

Alex