linux-kernel - Re: [PATCH v5 1/8] clocksource: dmtimer: Remove all the exports

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Date:   Tue, 12 Dec 2017 09:19:23 +0100
From:   Ladislav Michl <ladis@...ux-mips.org>
To:     Keerthy <j-keerthy@...com>
Cc:     tony@...mide.com, daniel.lezcano@...aro.org, aaro.koskinen@....fi,
        thierry.reding@...il.com, grygorii.strashko@...com,
        linux-omap@...r.kernel.org, robh+dt@...nel.org,
        linux-arm-kernel@...ts.infradead.org, linux-pwm@...r.kernel.org,
        sebastian.reichel@...labora.co.uk, linux-kernel@...r.kernel.org,
        t-kristo@...com, linux@...linux.org.uk
Subject: Re: [PATCH v5 1/8] clocksource: dmtimer: Remove all the exports

On Tue, Dec 12, 2017 at 01:38:04PM +0530, Keerthy wrote:
> On Tuesday 12 December 2017 01:31 PM, Ladislav Michl wrote:
> > On Tue, Dec 12, 2017 at 01:01:51PM +0530, Keerthy wrote:
> >>
> >>
> >> On Tuesday 12 December 2017 12:46 PM, Ladislav Michl wrote:
> >>> Keerthy,
> >>>
> >>> On Tue, Dec 12, 2017 at 11:42:10AM +0530, Keerthy wrote:
> >>>> Remove all the unwanted exports from the driver
> >>>
> >>> I'm adding event capture capability to the pwm-omap driver and so far used
> >>> v4.15-rc3 as codebase.
> >>>
> >>> Intended use is an IR receiver; for that I need to measure pulses width and
> >>> spaces between pulses. So DM timer was setup to generate interupt after
> >>> both TCAR1 and TCAR2 are filled, values are passed to IR decoder and
> >>> TCAR_IT_FLAG is cleared.
> >>>
> >>> Of course, this is just proof of concept and needs to be polished and
> >>> generalized, but to make it at least work I need functions you just
> >>> unexported (plus some new).
> >>>
> >>> Question is whenever we need this level of indirection (omap_dm_timer_ops)
> >>> or plain exports are enough.
> >>
> >> The general guidance is not to do plain exports and go via
> >> omap_dm_timer_ops.
> > 
> > ...in contrary what other clocksource drivers are doing.
> > 
> > Now I'm assuming it is okay to extend omap_dm_timer_ops. That would mean
> > check for ops members to be assigned should be also extended or we should
> > delete it altogether and assume all members are populated?
> 
> It should be fine to extend omap_dm_timer_ops. What are the ops missing
> for your new implementation?

Read capture registers, configure capture and ack interrupt. Perhaps set_pwm
could be extended to configure capture as well.

I'll update my code on top of your changes and we'll see how it would work.

> Tony,
> 
> Your thoughts on the above?
> 
> R