[PATCH v2 1/1] ARM: imx: clk-pllv3: change wait method for PLL lock

[u.kleine-koenig@pengutronix.de (Uwe Kleine-König)]

Hello Peter,

On Fri, Jun 07, 2013 at 04:43:55PM +0800, Peter Chen wrote:
> On Fri, Jun 07, 2013 at 10:35:28AM +0200, Uwe Kleine-K?nig wrote:
> > On Fri, Jun 07, 2013 at 04:31:35PM +0800, Peter Chen wrote:
> > > On Fri, Jun 07, 2013 at 10:24:57AM +0200, Uwe Kleine-K?nig wrote:
> > > > On Fri, Jun 07, 2013 at 04:19:06PM +0800, Peter Chen wrote:
> > > > > For some unknown reasons, the jiffies will be updated more
> > > > > than one tick at every short time. Eg, at this code:
> > > > > After timeout = jiffies + msecs_to_jiffies(10),
> > > > > the interrupt occurs, and the softirq updates jiffies (eg,  + 2 jiffies),
> > > > > then return back from interrupt, the time between above operations
> > > > > are tiny, the PLL is still not locked, but the timeout condition is satisfied.
> > > > > 
> > > > > Signed-off-by: Peter Chen <peter.chen@freescale.com>
> > > > Does this mean my patch doesn't solve the issue for you?
> > > 
> > > Not try, but your patch just delay timeout assignment, if there
> > > is jiffies update after that but before timeout check, it still
> > > has problem.
> > But if that large update happens because there was a long preemption the
> > pll should be locked because I only start counting when the pll is
> > programmed.
> > 
> > IMHO you should try my patch as it is the better fix (assuming it fixes
> > it for you).
> 
> I will try your fix, but still it just reduces the possibilities.
> The problem is not the preemption takes too long, it is the jiffies
> updates more than one tick at one short preemption.
If that is really the problem that many more instances that use the same
incarnation need the same fix. I would be surprised if that was the
case.

Best regards
Uwe

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