linux-kernel - Re: [PATCH 2/2] arm: omap_hwmod disable ick autoidling when a hwmod requires that

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Date:   Thu, 8 Nov 2018 12:08:47 +0100
From:   Andreas Kemnade <andreas@...nade.info>
To:     Tero Kristo <t-kristo@...com>
Cc:     <mturquette@...libre.com>, <sboyd@...nel.org>,
        <linux-omap@...r.kernel.org>, <linux-clk@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <bcousson@...libre.com>,
        <paul@...an.com>, <tony@...mide.com>,
        <letux-kernel@...nphoenux.org>
Subject: Re: [PATCH 2/2] arm: omap_hwmod disable ick autoidling when a hwmod
 requires that

Hi,

On Thu, 8 Nov 2018 12:26:08 +0200
Tero Kristo <t-kristo@...com> wrote:

> On 04/10/2018 23:38, Andreas Kemnade wrote:
> > Deny autoidle for hwmods with the OCPIF_SWSUP_IDLE flag,
> > that makes hwmods working properly which cannot handle
> > autoidle properly in lower power states.
> > Affected is e. g. the omap_hdq.
> > Since an ick might have mulitple users, autoidle is disabled
> > when an individual user requires that rather than in
> > _setup_iclk_autoidle. dss_ick is an example for that.
> > 
> > Signed-off-by: Andreas Kemnade <andreas@...nade.info>
> > ---
> >   arch/arm/mach-omap2/omap_hwmod.c | 16 ++++++++++++----
> >   1 file changed, 12 insertions(+), 4 deletions(-)
> > 
> > diff --git a/arch/arm/mach-omap2/omap_hwmod.c b/arch/arm/mach-omap2/omap_hwmod.c
> > index bb641e6c93d0..0078b0e1d242 100644
> > --- a/arch/arm/mach-omap2/omap_hwmod.c
> > +++ b/arch/arm/mach-omap2/omap_hwmod.c
> > @@ -986,8 +986,10 @@ static int _enable_clocks(struct omap_hwmod *oh)
> >   		clk_enable(oh->_clk);
> >   
> >   	list_for_each_entry(os, &oh->slave_ports, node) {
> > -		if (os->_clk && (os->flags & OCPIF_SWSUP_IDLE))
> > +		if (os->_clk && (os->flags & OCPIF_SWSUP_IDLE)) {
> > +			omap2_clk_deny_idle(os->_clk);  
> 
> I think calling this unconditionally across all platforms / clock types 
> might cause problems. Checking kernel, am33xx seems to have one clock 
> with this flag that is not of omap2 type. Do we have any testing data 
> that this doesn't break things?
> 
Somehow I have missed that am33xx clock. I have not tested it on that
platform. Concerning am3xxx I have only a beaglebone block but it not
am33xx I guess. So I have to recheck I guess.
But I think the intention of this flag was to control autoidle
vs. sw-controlled idle according to...
[...]
> >   		if (os->flags & OCPIF_SWSUP_IDLE) {
> > -			/* XXX omap_iclk_deny_idle(c); */
> > +			/*
this comment. So we need a if (clock_is_omap2()) or something like that
or remove that flag from any other clocks?

Regards,
Andreas

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