Date: Wed, 18 Mar 2015 07:44:39 +0100
From: Nicholas Mc Guire <der.herr@hofr.at>
To: Joe Perches <joe@perches.com>
Cc: Nicholas Mc Guire <hofrat@osadl.org>,
	Brett Rudley <brudley@broadcom.com>,
	Arend van Spriel <arend@broadcom.com>,
	"Franky (Zhenhui) Lin" <frankyl@broadcom.com>,
	Hante Meuleman <meuleman@broadcom.com>,
	Kalle Valo <kvalo@codeaurora.org>,
	"John W. Linville" <linville@tuxdriver.com>,
	Pieter-Paul Giesberts <pieterpg@broadcom.com>,
	Daniel Kim <dekim@broadcom.com>,
	Johannes Berg <johannes.berg@intel.com>,
	linux-wireless@vger.kernel.org, brcm80211-dev-list@broadcom.com,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] brcmfmac: cfg80211: use msecs_to_jiffies for time
	conversion
Message-ID: <20150318064439.GA25924@opentech.at> (sfid-20150318_074529_588362_3F6B6561)
References: <1426593972-17652-1-git-send-email-hofrat@osadl.org> <1426596159.23897.61.camel@perches.com>
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Sender: linux-wireless-owner@vger.kernel.org

On Tue, 17 Mar 2015, Joe Perches wrote:

> On Tue, 2015-03-17 at 08:06 -0400, Nicholas Mc Guire wrote:
> > Converting milliseconds to jiffies by "val * HZ / 1000" is technically
> > OK but msecs_to_jiffies(val) is the cleaner solution and handles all
> > corner cases correctly. This is a minor API consolidation only and
> > should make things more readable.
> 
> Hi Nicholas
> 
> These API consolidation changes now always have a function
> call when the compiler may have previously been able to
> optimize out the "constant * HZ / 1000" calculation.
>
> Perhaps the [um]secs_to_jiffies calls should be indirected
> with yet another static inline with a __builtin_constant_p()
> test so that the function calls can again be avoided when
> possible.

will give it a try 

> 
> (and a trivial style note)
> 
> > diff --git a/drivers/net/wireless/brcm80211/brcmfmac/cfg80211.c b/drivers/net/wireless/brcm80211/brcmfmac/cfg80211.c
> []
> > @@ -1110,7 +1110,7 @@ brcmf_cfg80211_escan(struct wiphy *wiphy, struct brcmf_cfg80211_vif *vif,
> >  
> >  	/* Arm scan timeout timer */
> >  	mod_timer(&cfg->escan_timeout, jiffies +
> > -			WL_ESCAN_TIMER_INTERVAL_MS * HZ / 1000);
> > +		  msecs_to_jiffies(WL_ESCAN_TIMER_INTERVAL_MS));
> 
> It may be nicer to keep the arithmetic on one line

sorry that was plain carelessness afer it went over 80 char.

> 
>  	mod_timer(&cfg->escan_timeout,
> 		  jiffies + msecs_to_jiffies(WL_ESCAN_TIMER_INTERVAL_MS));
>

thx!
hofrat