linux-kernel - Re: [PATCH v2 2/3] clk: ti: check clock type before doing autoidle ops

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Date:   Fri, 30 Nov 2018 15:51:55 -0800
From:   Stephen Boyd <sboyd@...nel.org>
To:     Tero Kristo <t-kristo@...com>, Tony Lindgren <tony@...mide.com>
Cc:     Andreas Kemnade <andreas@...nade.info>, bcousson@...libre.com,
        letux-kernel@...nphoenux.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
        mturquette@...libre.com, paul@...an.com
Subject: Re: [PATCH v2 2/3] clk: ti: check clock type before doing autoidle ops

Quoting Tony Lindgren (2018-11-30 07:37:29)
> Hi,
> 
> * Tero Kristo <t-kristo@...com> [181130 09:21]:
> > On 30/11/2018 09:57, Stephen Boyd wrote:
> > > No that is not preferred. Can the omap2_clk_deny_idle() function be
> > > integrated closer into the clk framework in some way that allows it to
> > > be part of the clk_ops structure? And then have that take a clk_hw
> > > structure instead of a struct clk? I haven't looked at this in any
> > > detail whatsoever so I may be way off right now.
> > 
> > It could be added under the main clk_ops struct, however this would
> > introduce two new func pointers to it which are not used by anything else
> > but OMAP. Are you aware of any other platforms requiring similar feature?
> 
> From consumer usage point of view, I'm still wondering about
> the relationship of clk_deny_idle() and clkdm_deny_idle().
> 
> It seems that we need to allow reset control drivers call
> clk_deny_idle() for the duration of reset. And it seems the
> clk_deny_idle() should propagate to also up to the related
> clock domain driver to do clkdm_deny_idle().
> 
> So maybe clk_deny_idle() is could just be something like:
> 
> dev = clk_get_device(clk);
> ...
> error = pm_runtime_get(dev);
> ...
> pm_runtime_put(dev);
> ...
> 
> And that way it would just propagate to the parent clock
> domain driver and the clock framework does not need to know
> about clockdomains. A clockdomain could be just a genpd
> domain.
> 
> Or do you guys have better ideas?
> 

Wouldn't the device link in clk framework patches do this for you if we
had the RUNTIME_PM flag passed in. If this is about keeping the clock
controller active when a consumer device is using it then I think it may
work.