linux-kernel - Re: [PATCH v6 3/7] scsi: ufs: introduce common delay function

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Message-ID: <1584404000.14250.28.camel@mtksdccf07>
Date:   Tue, 17 Mar 2020 08:13:20 +0800
From:   Stanley Chu <stanley.chu@...iatek.com>
To:     Bart Van Assche <bvanassche@....org>
CC:     <linux-scsi@...r.kernel.org>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        <avri.altman@....com>, <alim.akhtar@...sung.com>,
        <jejb@...ux.ibm.com>, <beanhuo@...ron.com>,
        <asutoshd@...eaurora.org>, <cang@...eaurora.org>,
        <matthias.bgg@...il.com>, <linux-mediatek@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <kuohong.wang@...iatek.com>,
        <peter.wang@...iatek.com>, <chun-hung.wu@...iatek.com>,
        <andy.teng@...iatek.com>
Subject: Re: [PATCH v6 3/7] scsi: ufs: introduce common delay function

Hi Bart,

On Mon, 2020-03-16 at 09:23 -0700, Bart Van Assche wrote:
> On 3/16/20 1:52 AM, Stanley Chu wrote:
> > +void ufshcd_wait_us(unsigned long us, unsigned long tolerance, bool can_sleep)
> > +{
> > +	if (!us)
> > +		return;
> > +
> > +	if (us < 10 || !can_sleep)
> > +		udelay(us);
> > +	else
> > +		usleep_range(us, us + tolerance);
> > +}
> > +EXPORT_SYMBOL_GPL(ufshcd_wait_us);
> 
> I don't like this function because I think it makes the UFS code harder 
> to read instead of easier. The 'can_sleep' argument is only set by one 
> caller which I think is a strong argument to remove that argument again 
> and to move the code that depends on that argument from the above 
> function into the caller. Additionally, it is not possible to comprehend 
> what a ufshcd_wait_us() call does without looking up the function 
> definition to see what the meaning of the third argument is.
> 
> Please drop this patch.

Thanks for your review and comments.

If the problem is the third argument 'can_sleep' which makes the code
not be easily comprehensible, how about just removing 'can_sleep' from
this function and keeping left parts because this function provides good
flexibility to users to choose udelay or usleep_range according to the
'us' argument?

Thanks,
Stanley Chu


> 
> Thanks,
> 
> Bart.
>