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Date: Mon, 20 Mar 2017 14:20:21 +0100
From: Thierry Reding <thierry.reding@gmail.com>
To: Peter De Schrijver <pdeschrijver@nvidia.com>
Cc: Prashant Gaikwad <pgaikwad@nvidia.com>,
	Michael Turquette <mturquette@baylibre.com>,
	Stephen Boyd <sboyd@codeaurora.org>,
	Stephen Warren <swarren@wwwdotorg.org>,
	Alexandre Courbot <gnurou@gmail.com>, linux-clk@vger.kernel.org,
	linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] clk: tegra: rework pll_u
Message-ID: <20170320132021.GH22463@ulmo.ba.sec>
References: <1489500769-28694-1-git-send-email-pdeschrijver@nvidia.com>
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On Tue, Mar 14, 2017 at 04:12:49PM +0200, Peter De Schrijver wrote:
> In normal operation pll_u is under hardware control and has a fixed rate =
of
> 480MHz. Hardware will turn on pll_u on whenever any of the XUSB
> powerdomains is on. From a software point of view we model this is if pll=
_u
> is always on using a fixed rate clock. However the bootloader might or
> might not have configured pll_u this way. So we will check the current
> state of pll_u at boot and reconfigure it if required.
>=20
> There are 3 possiblities at kernel boot:
> 1) pll_u is under hardware control: do nothing
> 2) pll_u is under hardware control and enabled: enable hardware control
> 3) pll_u is disabled: enable pll_u and enable hardware control
>=20
> In all cases we also check if UTMIPLL is under hardware control at boot
> and configure it for hardware control if that is not the case.
> The same is done during SC7 resume.
>=20
> Thanks to Joseph Lo <josephl@nvidia.com> for bug fixes.
>=20
> Signed-off-by: Peter De Schrijver <pdeschrijver@nvidia.com>
> ---
>  drivers/clk/tegra/clk-pll.c      | 174 -----------------------
>  drivers/clk/tegra/clk-tegra210.c | 295 +++++++++++++++++++++++++++++++++=
+++---
>  2 files changed, 272 insertions(+), 197 deletions(-)

Applied, thanks.

Do you think this actually fixes a bug? We've had a long standing issue
with booting Debian on a Jetson TX1 which is due to some USB related PLL
failing to lock. This sounds like it could fix that particular issue.

Thierry

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