linux-kernel - Re: [PATCH v2 05/21] ARM: tegra: clock: Disable clocks left on by bootloader

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Message-ID: <AANLkTin_4AfAgfWu=Qq_rO2T6o=u=JX9YKHquX85HrWe@mail.gmail.com>
Date:	Sun, 20 Feb 2011 19:43:35 -0800
From:	Colin Cross <ccross@...roid.com>
To:	Olof Johansson <olof@...om.net>
Cc:	linux-tegra@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	konkers@...roid.com, Russell King <linux@....linux.org.uk>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 05/21] ARM: tegra: clock: Disable clocks left on by bootloader

On Sun, Feb 20, 2011 at 4:40 PM, Olof Johansson <olof@...om.net> wrote:
> Hi,
>
> On Sat, Feb 19, 2011 at 2:25 PM, Colin Cross <ccross@...roid.com> wrote:
>> Adds CONFIG_TEGRA_DISABLE_BOOTLOADER_CLOCKS that iterates
>> through all clocks, disabling any for which the refcount
>> is 0 but the clock init detected the bootloader left the
>> clock on.
>
>
> I would argue that any kernel functionality that relies on clocks
> being left on my bootloader is buggy, and/or should at least have
> those clocks enabled in the static clock tables for the boards in
> question, since it creates an undocumented dependency on firmware.
>
> I would prefer if it disabled the clocks by default (after warning),
> but that there was a runtime way to override while debugging (i.e. add
> a bootarg 'keep_fwclocks' or similar to keep the firmware-enabled
> clocks running and just warn about them).

That was the plan, but since many of the drivers are missing I didn't
want to enable it by default yet.  However, it turns out the problems
I was seeing at boot from this patch were actually due to a bug in the
clock code causing the cpu clock to be disabled for clocks that have
no disable.  I will drop this patch, and post a separate series after
these that fixes the bug and turns off clocks by default, with a
runtime argument like you suggested.
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