From mboxrd@z Thu Jan  1 00:00:00 1970
From: dirk.behme@gmail.com (Dirk Behme)
Date: Sat, 25 May 2013 07:59:45 +0200
Subject: clock framework: Don't disable a clock already enabled by boot
 loader?
In-Reply-To: <20130524230021.GF31135@pengutronix.de>
References: <519F60CA.6090302@de.bosch.com>
 <20130524230021.GF31135@pengutronix.de>
Message-ID: <51A05351.7000501@gmail.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

Hi Sascha,

Am 25.05.2013 01:00, schrieb Sascha Hauer:
> Hi Dirk,
>
> On Fri, May 24, 2013 at 02:44:58PM +0200, Dirk Behme wrote:
>> Hi,
>>
>> we register a clock using clk_register_clkdev() etc already enabled
>> by a boot loader. We are doing only the clk_register_clkdev(), but
>> no clock_enable() etc on this clock.
>>
>> With this, enable_count for this clock is zero, while in fact it's
>> already on. I.e. the kernel doesn't know that it is on.
>>
>> This results in
>>
>> late_initcall(clk_disable_unused())
>>
>> disabling this clock because the kernel thinks it's unused.
>>
>> Is this the intended behavior?
>
> Yes, and it's great since after this point the hardware state is in sync
> with the enable counter.
>
>> Is there a way to let the kernel know
>> "the clock is enabled already, set enable_count != 0"? Or is the
>> only way to do this correctly calling clock_enable() on an already
>> enabled clock?
>
> You could set the CLK_IGNORE_UNUSED flag in the clock, but I suggest to
> just clk_get/clk_enable the clock in the driver using it.

Thanks for the fast answer! :)

Hmm, but what's the best way to set a flag in

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/arm/mach-imx/clk-imx6q.c

?

In mx6q_clocks_init() there doesn't seem to be an explicit interface 
to set the flags?

I'm not sure if

clk[xxx]->flags |= CLK_IGNORE_UNUSED;

is the way to go?

Best regards

Dirk