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

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Date:   Tue, 12 Dec 2017 19:03:17 +0100
From:   Ladislav Michl <ladis@...ux-mips.org>
To:     Tony Lindgren <tony@...mide.com>
Cc:     Keerthy <j-keerthy@...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 09:00:54AM -0800, Tony Lindgren wrote:
> Hmm what do you mean? We don't want to export tons of custom functions from
> the timers in and then be in trouble when at some point we have a Linux
> generic hw timer framework. We already had to deal with these custom
> exports earlier with conversion to multiarch and then again with
> device tree.
>
> For now, it's best to pass the timer information to the pwm driver in
> platform data. In the long run that will be much easier to deal with than
> fixing random drivers tinkering with the timer registers directly.

All that register access would happen only in drivers/clocksource/timer-dm.c?
So platform data will hold all function pointers needed for event capture
and the pwm driver will do only interface to pwm framework.

> Ideally the pwm driver would just do a request_irq from the dmtimer code
> where dmtimer code would implement an interrupt controller. That would
> be already most fo the Linux generic hardware timer framework right there :)

I do not follow. Each general-purpose timer module has its own interrupt line,
so claiming that irq directly using request_irq seems enough. Could you
explain interrupt controller idea a bit more?

Thank you,
	ladis