Re: [PATCH 0/2] OMAP3: wdtimer: fix wdtimer blocking CORE idle

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Hi Benoît,

On Thu, 10 Mar 2011, Cousson, Benoit wrote:

> On 3/10/2011 11:28 AM, kalle.jokiniemi@xxxxxxxxx wrote:
> > 
> > 
> > > -----Original Message-----
> > > From: ext Paul Walmsley [mailto:paul@xxxxxxxxx]
> > > Sent: 10. maaliskuuta 2011 11:50
> > > To: Jokiniemi Kalle (Nokia-MS/Tampere)
> > > Cc: khilman@xxxxxx; linux-omap@xxxxxxxxxxxxxxx; Koskinen Ilkka (Nokia-
> > > MS/Tampere); jhnikula@xxxxxxxxx; b-cousson@xxxxxx
> > > Subject: Re: [PATCH 0/2] OMAP3: wdtimer: fix wdtimer blocking CORE idle
> > > 
> > > 
> > > Thanks Kalle for tracking this down,
> > > 
> > > could you try this patch along with the patch from this message:
> > > 
> > >    http://www.spinics.net/lists/linux-omap/msg48115.html
> 
> I have some question with that patch.
> By using pm_runtime API, you are suppose to idle the whole IP.
> In this case, just because you cannot idle a wdt that is running, it works,
> but the point is that the pm_runtime state will not reflect the HW state.
> For pm_runtime point of view, the wdt is supposed to be fully idle (both fclk
> and iclk). Whereas in that case, only the iclk will be gated.
> 
> Did I miss something?

Looking at it, I don't know how the old driver managed to work at all.  
Commit 7ec5ad0f3c1e28b693185c35f768953c5db32291 ("OMAP: WDT: Use PM 
runtime APIs instead of clk FW APIs") removed this from omap_wdt_probe():

-       /* autogate OCP interface clock */
-       __raw_writel(0x01, wdev->base + OMAP_WATCHDOG_SYS_CONFIG);

This would put the WDTIMER into force-idle, and nothing ever took it out 
of force-idle.  So I don't quite understand why the PRCM wouldn't just 
turn off the functional clock to the WDTIMER at this point.  Any thoughts 
on this?


- Paul

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