linux-kernel - Re: [PATCH v2 2/2] clk: tegra20: Enable lock-status polling for PLLs

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Date:   Mon, 10 Dec 2018 03:58:36 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Marcel Ziswiler <marcel.ziswiler@...adex.com>,
        "pdeschrijver@...dia.com" <pdeschrijver@...dia.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "jonathanh@...dia.com" <jonathanh@...dia.com>,
        "mturquette@...libre.com" <mturquette@...libre.com>,
        "pgaikwad@...dia.com" <pgaikwad@...dia.com>,
        "sboyd@...nel.org" <sboyd@...nel.org>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] clk: tegra20: Enable lock-status polling for
 PLLs

В Wed, 17 Oct 2018 14:41:35 +0300
Dmitry Osipenko <digetx@...il.com> пишет:

> On 10/17/18 1:59 PM, Marcel Ziswiler wrote:
> > On Fri, 2018-08-31 at 12:29 +0300, Peter De Schrijver wrote:  
> >> On Thu, Aug 30, 2018 at 09:42:10PM +0300, Dmitry Osipenko wrote:  
> >>> Currently all PLL's on Tegra20 use a hardcoded delay despite of
> >>> having
> >>> a lock-status bit. The lock-status polling was disabled ~7 years
> >>> ago
> >>> because PLLE was failing to lock and was a suspicion that other
> >>> PLLs
> >>> might be faulty too. Other PLLs are okay, hence enable the lock-
> >>> status
> >>> polling for them. This reduces delay of any operation that require
> >>> PLL
> >>> to lock.
> >>>
> >>> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> >>> ---
> >>>
> >>> Changelog:
> >>>
> >>> v2:	Don't enable polling for PLLE as it known to not being
> >>> able to lock.
> >>>  
> >>
> >> This isn't correct. The lock bit of PLLE can declare lock too
> >> early, but the
> >> PLL itself does lock.  
> > 
> > Is there an errata documenting this? As I could not really find any
> > mentioning of this anywhere at least up to the v11 from Dec 21,
> > 2010 I still have access to.
> > 
> > BTW: It looks like also PLLA may not always lock properly with those
> > changes. Is there anything known about that as well? Here is what I
> > get on various Colibri T20 modules (while random other ones seem to
> > work fine):  
> Could you please try to increase the timeout value?

Hello Marcel,

Do you have any update on the PLL-lock-failure problem?