Date: Wed, 14 Nov 2012 11:54:06 +0100
From: Thierry Reding <thierry.reding@avionic-design.de>
To: Terje =?utf-8?Q?Bergstr=C3=B6m?= <tbergstrom@nvidia.com>
Cc: Stephen Warren <swarren@wwwdotorg.org>,
        "linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] ARM: tegra: Add Tegra20 host1x support
Message-ID: <20121114105406.GA31455@avionic-0098.mockup.avionic-design.de>
References: <1352467202-27903-1-git-send-email-thierry.reding@avionic-design.de>
 <1352467202-27903-2-git-send-email-thierry.reding@avionic-design.de>
 <50A357D3.9080002@nvidia.com>
 <20121114084931.GA31837@avionic-0098.mockup.avionic-design.de>
 <50A3712E.7000104@nvidia.com>
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On Wed, Nov 14, 2012 at 12:23:42PM +0200, Terje Bergstr=C3=B6m wrote:
> On 14.11.2012 10:49, Thierry Reding wrote:
> > Can you find out how the host1x clock is setup without this change? I
> > was told that freezes can occur when you try to access the registers
> > without the host1x clock being enabled. However, the host1x driver
> > should take care to properly setup the clock.
> >=20
> > To find out if the non-running clock is the issue, can you try to patch
> > that line and make the final element true instead of false? That should
> > enable the clock on boot so that it should always be running.
>=20
> I tried with fastboot and U-Boot, and whenever that line is there,
> kernel boot will halt at nvhost init. Same happens if I just change the
> false to true.
>=20
> nvhost will enable the clock and disable as it need. Also, part of
> host1x initialization did proceed, but it ended up hanging after a few
> registers were initialized. So it's not a case of host1x being off, but
> host1x hanging after a while.
>=20
> If I change this line to:
>=20
>        { "host1x",     "pll_p",        216000000,      false },
>=20
> it will also work properly. It looks like we have some problem with
> pll_c in Tegra20, or clock configuration with your patch. In Tegra30,
> pll_c with 144MHz seems to work fine, but on Tegra20, it doesn't.
>=20
> In internal kernel, we use pll_c for host1x, so hardware shouldn't be
> the problem here.

I suppose that if things work properly without this line, then we should
probably just drop it. Stephen, any objections?

Thierry

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