linux-kernel - Re: [PATCH/RFC 2/2] arm/tegra: add timeout to PCIe PLL lock detection loop

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Date:	Tue, 6 Mar 2012 20:09:12 +0100
From:	Thierry Reding <thierry.reding@...onic-design.de>
To:	Stephen Warren <swarren@...dotorg.org>
Cc:	Dmitry Artamonow <mad_soft@...ox.ru>, linux-tegra@...r.kernel.org,
	Colin Cross <ccross@...roid.com>,
	Olof Johansson <olof@...om.net>,
	Stephen Warren <swarren@...dia.com>,
	Mike Rapoport <mike@...pulab.co.il>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH/RFC 2/2] arm/tegra: add timeout to PCIe PLL lock
 detection loop

* Stephen Warren wrote:
> On 03/06/2012 01:45 AM, Dmitry Artamonow wrote:
> > Tegra PCIe driver waits for PLL to lock using busy loop.
> > If PLL fails to lock for some reason, this leads to silent lockup
> > while booting (as PCIe code is not modular).
> > 
> > Fix by adding timeout, so if PLL doesn't lock in a couple
> > of seconds, just PCIe driver fails and machine continues to boot.
> > 
> > Signed-off-by: Dmitry Artamonow <mad_soft@...ox.ru>
> 
> That seems reasonable. So once the mdelay discussion is resolved,
> 
> Acked-by: Stephen Warren <swarren@...dotorg.org>
> 
> Any idea why the PLL doesn't lock sometimes?

I've seen this happen when the 1.05V regulator (GPIO#2 of the PMU on Harmony)
isn't enabled.

Thierry

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