Re: [RFC PATCH v4 3/3] PM / clock_ops: add and enable clocks always if !CONFIG_PM_RUNTIME

[Grygorii Strashko]

On 11/06/2014 08:09 PM, Dmitry Torokhov wrote:
> On Thu, Nov 06, 2014 at 03:51:02PM +0200, Grygorii Strashko wrote:
> > Device's clocks need to be enabled always at probing time
> > if !CONFIG_PM_RUNTIME - in that way, device will become accesible
> > and, later, its clocks can be disabled/enabled during system
> > suspend/resume by using pm_clk_suspend/pm_clk_resume APIs.
> >
> > But now, the clocks management code doesn't enable clocks when
> > clocks are being registered per-device by using pm_clk_add/_clk().
> > So, update pm_clk_acquire(), which is called from pm_clk_add/_clk(),
> > to enable clock always if !CONFIG_PM_RUNTIME.
> >
> > Also, Platform PM domains drivers will not have to add code like below
> > each time they need to handle the case when !CONFIG_PM_RUNTIME [1 - 3]:
> >
> >         if (!IS_ENABLED(CONFIG_PM_RUNTIME)) {
> >                 ret = pm_clk_resume(dev);
> >                 if (ret) {
> >                         dev_err(dev, "pm_clk_resume failed %d\n", ret);
> >                         goto clk_err;
> >                 };
> >         }
> >
> > [1] https://lkml.org/lkml/2014/10/3/306
> > [2] https://lkml.org/lkml/2014/10/16/305
> > [3] https://lkml.org/lkml/2014/10/20/249
> >
> > CC: Santosh Shilimkar <ssantosh@xxxxxxxxxx>
> > CC: Kevin Hilman <khilman@xxxxxxxxxx>
> > CC: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
> > CC: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> > CC: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> > CC: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
> > CC: Caesar Wang <caesar.wang@xxxxxxxxxxxxxx>
> >
> > Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx>
> > ---
> > Hi,
> >
> > I marked it as RFC, because:
> >    Generic clock manipulation PM callbacks can be used for any device
> >    for which list of clocks need to be maintained - and it doesn't mean
> >    that this framework need to be always connected to GPD/Runtime PM or
> >    used during suspend resume. Also, for DT-use case - it doesn't perform
> >    any actions (except clk_prepare) on clocks by itself and only
> >    by request from framework's consumer.
> >
> >   For example, it can be reused by Power domain/controller drivers like:
> >   - Rockchip RK3288 PM Domain (https://lkml.org/lkml/2014/11/6/30)
> >   - IMX.6 PU power domain (http://www.spinics.net/lists/arm-kernel/msg360709.html)
> >
> >   to maintain list of clocks for GPD itself and these clocks should not
> >   be enabled by default, because they are used to power on/off Power domain
> >   in a specific way:
> >       - enable all clocks assigned to PD
> >       - power on/off PD
> >       - disable all clocks assigned to PD.
> >   After this patch it will be impossible to reuse Generic clock manipulation PM
> >   callbacks in cases described above.
>
> I'd rather keep it separate and concentrate on making pm_clk* code
> working with the power management core. Individual drivers can easily
> keep list of their clocks for whatever additional purpose they need
> without involving pm_clk* API.

In general, I'm ok with this patch for Keystone 2 proposes,
just added some notes about introduced limitations. And  all
current users of pm_clk* APIs will not regress with this patch, because
they will go through different code path if !CONFIG_PM_RUNTIME.

Regards,
-grygorii




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