[PATCH 2/2 v2] [ARM] [IMX]: Fix clock use counter from underflow on multiple clk_disable().

[vzapolskiy@gmail.com (Vladimir Zapolskiy)]

Hi Uwe

2010/3/18 Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>:
> Hi Vladimir,
>
> On Wed, Mar 17, 2010 at 02:03:31PM +0300, Vladimir Zapolskiy wrote:
>> If clk_disable() is called for already disabled clock clk->usecount
>> value is decremented anyway. This leads to a problem that sequent
>> clk_enable() call doesn't enable the clock as expected.
>>
>> Signed-off-by: Vladimir Zapolskiy <vzapolskiy@gmail.com>
>> Cc: Sascha Hauer <s.hauer@pengutronix.de>
>> Cc: Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>
>> ---
>> ?arch/arm/plat-mxc/clock.c | ? ?6 +++++-
>> ?1 files changed, 5 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/arm/plat-mxc/clock.c b/arch/arm/plat-mxc/clock.c
>> index 2daec3c..3189275 100644
>> --- a/arch/arm/plat-mxc/clock.c
>> +++ b/arch/arm/plat-mxc/clock.c
>> @@ -53,10 +53,14 @@ static void __clk_disable(struct clk *clk)
>> ? ? ? if (clk == NULL || IS_ERR(clk))
>> ? ? ? ? ? ? ? return;
>>
>> + ? ? if (!clk->usecount) {
>> + ? ? ? ? ? ? WARN(1, "Trying to disable a clock with 0 usecount\n");
>> + ? ? ? ? ? ? return;
>> + ? ? }
>> +
> The advantage of just using
>
> ? ? ? ?WARN(!clk->usecount, "Trying to disable a disabled clock\n");
>
> is that the error isn't caught and so is more likely to be fixed :-)
> I'n not a native English speaker, but I think "Trying to disable a clock
> with 0 usecount" isn't a proper English sentence.
>

I see, thank you. But why don't you use BUG() here, if this testifies
to a higher level bug and after such a call the whole kernel can be
unmaintainable on run-time?

> Best regards
> Uwe
>

Best wishes,
Vladimir