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

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Date:	Fri, 13 May 2016 22:47:05 +0530
From:	Muhammad Falak R Wani <falakreyaz@...il.com>
To:	Jani Nikula <jani.nikula@...ux.intel.com>
Cc:	Christian Knig <christian.koenig@....com>,
	Nils Wallménius <nils.wallmenius@...il.com>,
	Jammy Zhou <Jammy.Zhou@....com>, linux-kernel@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	Alex Deucher <alexander.deucher@....com>,
	Rex Zhu <Rex.Zhu@....com>,
	Dan Carpenter <dan.carpenter@...cle.com>
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.