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SubjectRe: [PATCH] arm: mxc: utilise usecount field in clock operations
On 10 Apr 22, Sascha Hauer wrote:
> On Wed, Apr 21, 2010 at 09:37:31PM +0300, Amit Kucheria wrote:
> > clk->usecount can be used by platform code to check if a clock is active or
> > not.
>
> The patch seems mostly fine but the commit log not. How about something like
> 'This patch fixes the clock refcounting when reparenting is used.'
>
> A reference to
>
> http://www.spinics.net/lists/arm-kernel/msg85879.html
>
> might help aswell.

Interesting. I had no idea about this work. I was just resurrecting old
patches from January.

Will fix and resend.

/Amit

> >
> > Signed-off-by: Amit Kucheria <amit.kucheria@canonical.com>
> > ---
> > arch/arm/plat-mxc/clock.c | 37 ++++++++++++++++++++++++-------------
> > 1 files changed, 24 insertions(+), 13 deletions(-)
> >
> > diff --git a/arch/arm/plat-mxc/clock.c b/arch/arm/plat-mxc/clock.c
> > index 323ff8c..c791f38 100644
> > --- a/arch/arm/plat-mxc/clock.c
> > +++ b/arch/arm/plat-mxc/clock.c
> > @@ -50,15 +50,15 @@ static DEFINE_MUTEX(clocks_mutex);
> >
> > static void __clk_disable(struct clk *clk)
> > {
> > - if (clk == NULL || IS_ERR(clk))
> > + if (clk == NULL || IS_ERR(clk) || !clk->usecount)
> > return;
> >
> > - __clk_disable(clk->parent);
> > - __clk_disable(clk->secondary);
> > -
> > - WARN_ON(!clk->usecount);
> > - if (!(--clk->usecount) && clk->disable)
> > - clk->disable(clk);
> > + if (!(--clk->usecount)) {
> > + if (clk->disable)
> > + clk->disable(clk);
> > + __clk_disable(clk->parent);
> > + __clk_disable(clk->secondary);
> > + }
> > }
> >
> > static int __clk_enable(struct clk *clk)
> > @@ -66,12 +66,13 @@ static int __clk_enable(struct clk *clk)
> > if (clk == NULL || IS_ERR(clk))
> > return -EINVAL;
> >
> > - __clk_enable(clk->parent);
> > - __clk_enable(clk->secondary);
> > -
> > - if (clk->usecount++ == 0 && clk->enable)
> > - clk->enable(clk);
> > + if (clk->usecount++ == 0) {
> > + __clk_enable(clk->parent);
> > + __clk_enable(clk->secondary);
> >
> > + if (clk->enable)
> > + clk->enable(clk);
> > + }
> > return 0;
> > }
> >
> > @@ -160,17 +161,27 @@ EXPORT_SYMBOL(clk_set_rate);
> > int clk_set_parent(struct clk *clk, struct clk *parent)
> > {
> > int ret = -EINVAL;
> > + struct clk *prev_parent = clk->parent;
> >
> > if (clk == NULL || IS_ERR(clk) || parent == NULL ||
> > IS_ERR(parent) || clk->set_parent == NULL)
> > return ret;
> >
> > + if (clk->usecount != 0) {
> > + clk_enable(parent);
> > + }
> > +
> > mutex_lock(&clocks_mutex);
> > ret = clk->set_parent(clk, parent);
> > - if (ret == 0)
> > + if (ret == 0) {
> > clk->parent = parent;
> > + }
>
> Please remove this hunk. It does not change anything except violating
> the coding style. Also, please remove unnecessary braces.
>
> > mutex_unlock(&clocks_mutex);
> >
> > + if (clk->usecount != 0) {
> > + clk_disable(prev_parent);
> > + }
> > +
> > return ret;
> > }
> > EXPORT_SYMBOL(clk_set_parent);
> > --
> > 1.7.0.4
> >
> >
>
> --
> Pengutronix e.K. | |
> Industrial Linux Solutions | http://www.pengutronix.de/ |
> Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
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--
----------------------------------------------------------------------
Amit Kucheria, Kernel Engineer || amit.kucheria@canonical.com
----------------------------------------------------------------------


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