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

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Date:   Mon, 3 Sep 2018 11:01:11 +0300
From:   Peter De Schrijver <pdeschrijver@...dia.com>
To:     Dmitry Osipenko <digetx@...il.com>
CC:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Prashant Gaikwad <pgaikwad@...dia.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, <linux-clk@...r.kernel.org>,
        <linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] clk: tegra20: Enable lock-status polling for PLLs

On Fri, Aug 31, 2018 at 12:45:17PM +0300, Dmitry Osipenko wrote:
> On 8/31/18 12:29 PM, 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.
> 
> Indeed, it locks but can't be polled for the lock-status as it doesn't have the
> lock-status bit.
> 
> Do you want me to adjust the commit description or it is fine as is?
> 

I think it's better to adjust it.

> It is also a bit odd that PLLE has "lock_delay = 0", is it correct?

That seems odd yes..

Peter.