* Eduardo Valentin <edubezval@xxxxxxxxx> [080330 21:49]:
> Hi Tony and Paul,
>
> Just a little question/warn, these kind of code may not be preempt safe:
> <snip>
> +/* Enables clock without considering parent dependencies or use count
> + * REVISIT: Maybe change this to use clk->enable like on omap1?
> + */
> +int _omap2_clk_enable(struct clk *clk)
> +{
> + u32 regval32;
> +
> + if (clk->flags & (ALWAYS_ENABLED | PARENT_CONTROLS_CLOCK))
> + return 0;
> +
> + if (clk->enable)
> + return clk->enable(clk);
> +
> + if (unlikely(clk->enable_reg == 0)) {
> + printk(KERN_ERR "clock.c: Enable for %s without enable code\n",
> + clk->name);
> + return 0; /* REVISIT: -EINVAL */
> + }
> +
> + regval32 = cm_read_reg(clk->enable_reg);
> + if (clk->flags & INVERT_ENABLE)
> + regval32 &= ~(1 << clk->enable_bit);
> + else
> + regval32 |= (1 << clk->enable_bit);
> + cm_write_reg(regval32, clk->enable_reg);
> + wmb();
> +
> + omap2_clk_wait_ready(clk);
> +
> + return 0;
> +}
> <snip>
>
> Are these registers protected somehow? because this read followed by a write
> may not be a preempt safe operation. Or this code is not designed for
> CONFIG_PREEMPT?
Yeah, it's OK. Both clk24xx.c and clk34xx.c register omap2_clk_enable()
with omap common clock code.
Then omap common clock code calls omap2_clk_enable() with spin_lock_irqsave(),
see clk_enable() in arch/arm/plat-omap/clock.c.
Regards,
Tony
>
> Cheers,
>
> Eduardo Valentin
>
> On Fri, Mar 28, 2008 at 8:38 AM, Tony Lindgren <tony@xxxxxxxxxxx> wrote:
> > * Tony Lindgren <tony@xxxxxxxxxxx> [080318 17:04]:
> >
> > > From: Paul Walmsley <paul@xxxxxxxxx>
> > >
> > > This patch adds a common clock framework for 24xx and 34xx.
> > > Note that this patch does not add it to Makefile until in
> > > next patch. Some functions are modified from earlier 24xx
> > > clock framework code.
> >
> > Here's an updated version of this patch. I've folded in two more patches
> > from Paul [1][2]. Patches change to use __ffs() instead of
> > mask_to_shift,
> > and clean up clock register defines.
> >
> > Regards,
> >
> > Tony
> >
> > [1] http://master.kernel.org/git/?p=linux/kernel/git/tmlind/linux-omap-2.6.git;a=commitdiff;h=f417e171cd2d2bd0302c8f420ee97295a165a39c
> > [2] http://master.kernel.org/git/?p=linux/kernel/git/tmlind/linux-omap-2.6.git;a=commitdiff;h=70d19cc5c7999445b84e6ffea8e025512b877e8c
> >
>
>
>
> --
> Eduardo Bezerra Valentin
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