linux-kernel - Re: [PATCH 46/58] clocksource/drivers: Add a new driver for the Atmel ARM TC blocks

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Date:   Wed, 7 Jun 2017 23:08:48 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Cc:     Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 46/58] clocksource/drivers: Add a new driver for the
 Atmel ARM TC blocks

On Wed, Jun 07, 2017 at 05:27:50PM +0200, Alexandre Belloni wrote:
> On 07/06/2017 at 16:17:35 +0200, Daniel Lezcano wrote:
> > > You mean you don't like how it is used? Or you don't think having the
> > > timer full name is useful?
> > 
> > The field is not needed, the only place where it is used is where we affect it.
> >  
> 
> It is used in tcb_clksrc_register:
> 
> tc.clksrc.name = tc.name;

Yes, but tc.name is only in the scope of the function, so there is no need to
include this field in the structure, just a working buffer in the function is
enough.
 
> > > The main reason is that RobH doesn't want to have the use (clocksource
> > > or clockevent) of the timer in the DT so when probing a timer, I need to
> > > know whether I already have a clocksource to decide when it is time to
> > > register a clockevent.
> > 
> > Yes, we had this discussion some weeks ago.
> > 
> > This registered hack forces the DT to define first the clocksource, then the
> > clockevent.
> > 
> > So, I suggest you fold the timer definition into a single one like the other
> > drivers.
> 
> I was going to agree but this is not flexible enough because the
> quadrature decoder always uses the first two channels. So on some
> products, we may have:
>  - TCB0:
>    o channels 0,1: qdec
>    o channel 2: clocksource
> 
>  - TCB1:
>    o channels 0,1: qdec
>    o channel 2: clockevent
> 
> This avoids wasting TCB channels.

Ok. In this case you can check if the interrupt is specified for the node, if
yes, then it is a clockevent.

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