linux-kernel - Re: [PATCH 1/2] mfd: madera: Allow more time for hardware reset

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Message-ID: <20200113104141.GC5414@dell>
Date:   Mon, 13 Jan 2020 10:41:41 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Charles Keepax <ckeepax@...nsource.cirrus.com>
Cc:     linux-kernel@...r.kernel.org, patches@...nsource.cirrus.com
Subject: Re: [PATCH 1/2] mfd: madera: Allow more time for hardware reset

On Wed, 08 Jan 2020, Charles Keepax wrote:

> On Tue, Jan 07, 2020 at 02:27:42PM +0000, Lee Jones wrote:
> > On Mon, 06 Jan 2020, Charles Keepax wrote:
> > 
> > > Both manual and power on resets have a brief period where the chip will
> > > not be accessible immediately afterwards. Extend the time allowed for
> > > this from a minimum of 1mS to 2mS based on newer evaluation of the
> > > hardware and ensure this reset happens in all reset conditions. Whilst
> > > making the change also remove the redundant NULL checks in the reset
> > > functions as the GPIO functions already check for this.
> > > 
> > > Signed-off-by: Charles Keepax <ckeepax@...nsource.cirrus.com>
> > > ---
> > >  drivers/mfd/madera-core.c | 18 ++++++++++--------
> > >  1 file changed, 10 insertions(+), 8 deletions(-)
> > > 
> > > diff --git a/drivers/mfd/madera-core.c b/drivers/mfd/madera-core.c
> > > index a8cfadc1fc01e..f41ce408259fb 100644
> > > --- a/drivers/mfd/madera-core.c
> > > +++ b/drivers/mfd/madera-core.c
> > > @@ -238,6 +238,11 @@ static int madera_wait_for_boot(struct madera *madera)
> > >  	return ret;
> > >  }
> > >  
> > > +static inline void madera_reset_delay(void)
> > > +{
> > > +	usleep_range(2000, 3000);
> > > +}
> > 
> > Hmm ... We usually shy away from abstraction for the sake of
> > abstraction.  What's preventing you from using the preferred method of
> > simply calling the abstracted function from each of the call-sites?
> > 
> > I could understand (a little) if you needed to frequently change these
> > values, since changing them in once place is obviously simpler than
> > changing them in 3, but even then it's marginal.
> > 
> 
> I don't mind manually inline it, we don't plan on changing the
> values very often certainly. It really was just to avoid future
> bugs if someone adds a new place that needs the delay or does
> indeed change the delay. Would you mind if I used a define for
> the time instead, if I am manually inlining? That keeps the same
> single place to update, but without the extra function.

That would be my preference, yes.

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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