Re: [PATCH 1/4] Add smp support for Allwinner A20(sunxi 7i).

From: Russell King - ARM Linux
Date: Thu Sep 12 2013 - 10:41:58 EST


Some other comments:

On Thu, Sep 12, 2013 at 02:51:24PM +0800, Fan Rong wrote:
> + /* L1RSTDISABLE hold low */
> + pwr_reg = readl(cc_base + AW_CPUCFG_GENCTL);
> + pwr_reg &= ~(1<<cpu);

If you pass your patch through checkpatch.pl, it will warn about some of
this. You should have one space each side of <<.

> + /* step3: clear power-off gating */
> + pwr_reg = readl(cc_base + AW_CPU1_PWROFF_REG);
> + pwr_reg &= ~(1);

You don't need the parens here.

> + pwr_reg = readl(cc_base + AW_CPUCFG_DBGCTL1);
> + pwr_reg |= (1<<cpu);

Nor here.

> +static int sunxi7i_boot_secondary(unsigned int cpu, struct task_struct *idle)
> +{
> + pr_debug("[%s] enter cpu %d\n", __func__, cpu);
> + spin_lock(&boot_lock);
> + enable_aw_cpu(cpu);
> + spin_unlock(&boot_lock);

What exactly does this spinlock protect? The core code already provides
the guarantee that only one CPU will be brought online or taken offline
at a time.
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