linux-kernel - Re: [PATCH v3 3/3] arm: omap_hwmod disable ick autoidling when a hwmod requires that

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Date:   Mon, 21 Jan 2019 18:53:44 +0100
From:   Andreas Kemnade <andreas@...nade.info>
To:     Tony Lindgren <tony@...mide.com>
Cc:     Tero Kristo <t-kristo@...com>, 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, letux-kernel@...nphoenux.org
Subject: Re: [PATCH v3 3/3] arm: omap_hwmod disable ick autoidling when a
 hwmod requires that

Hi,

On Mon, 21 Jan 2019 09:07:43 -0800
Tony Lindgren <tony@...mide.com> wrote:

> * Tero Kristo <t-kristo@...com> [190121 07:13]:
> > On 18/01/2019 21:45, Tony Lindgren wrote:  
> > > * Andreas Kemnade <andreas@...nade.info> [190118 19:39]:  
> > > > Hi,
> > > > 
> > > > On Fri, 18 Jan 2019 10:36:30 -0800
> > > > Tony Lindgren <tony@...mide.com> wrote:
> > > > 
> > > > [...]  
> > > > > til the next workaround.
> > > > >   
> > > > > > That flags also causes the iclk being enabled/disabled
> > > > > > manually.  
> > > > > 
> > > > > Yes but SWSUP_IDLE for the interface clock to me currently
> > > > > just means:
> > > > > 
> > > > > "manually enable and disable ocp interface clock"
> > > > >   
> > > > well, if we want to manually disable it and not automatically,
> > > > we have to disable autoidle or it will be automatically disabled.
> > > > 
> > > > Disabling it manually when it is already auto-disabled (by autoidle) is
> > > > just practically a no-op towards the clock.  
> > > 
> > > OK I buy that :) It should be probably added to the patch
> > > description to make it clear what it changes.
> > > 
> > > Tero, any comments on this change?  
> > 
> > Well, seeing the flag is pretty much only used for a handful of hwmods
> > nowadays, it should be fine. OMAP3 PM should be tested with this change
> > though, as there are couple of hwmods impacted on that platform. I wonder
> > what happens to cpuidle when display is active...  
> 
> OK so that's a good test case. AFAIK, we should have DSS idle
> and have the SoC hit at least core retention with DSI command mode
> displays. I don't know if this patch would block DSS autoidle then
> or not.. I'm guessing 80% chance that we still need DSS hit runtime
> suspend to enter SoC idle states meaning this patch would not
> affect it :)
> 
So this is a call to Nokia N950 owners?
Unfortunately, I do not have one. I have seen on non-command-mode
displays that dss goes to idle when display is blanked.

Regards,
Andreas

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