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Commit a5e1baf7 authored by Heiko Stübner's avatar Heiko Stübner Committed by Michael Turquette
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clk: rockchip: fix deadlock possibility in cpuclk 



Lockdep reported a possible deadlock between the cpuclk lock and for example
the i2c driver.

       CPU0                    CPU1
       ----                    ----
  lock(clk_lock);
                               local_irq_disable();
                               lock(&(&i2c->lock)->rlock);
                               lock(clk_lock);
  <Interrupt>
    lock(&(&i2c->lock)->rlock);

 *** DEADLOCK ***

The generic clock-types of the core ccf already use spin_lock_irqsave when
touching clock registers, so do the same for the cpuclk.

Signed-off-by: default avatarHeiko Stuebner <heiko@sntech.de>
Reviewed-by: default avatarDoug Anderson <dianders@chromium.org>
Signed-off-by: default avatarMichael Turquette <mturquette@linaro.org>
[mturquette@linaro.org: removed initialization of "flags"]
parent b71e8ecd

drivers/clk/rockchip/clk-cpu.c

+6 −4
Original line number Original line Diff line number Diff line
@@ -124,10 +124,11 @@ static int rockchip_cpuclk_pre_rate_change(struct rockchip_cpuclk *cpuclk, 
{

{

	const struct rockchip_cpuclk_reg_data *reg_data = cpuclk->reg_data;

	const struct rockchip_cpuclk_reg_data *reg_data = cpuclk->reg_data;

	unsigned long alt_prate, alt_div;

	unsigned long alt_prate, alt_div;

	unsigned long flags;





	alt_prate = clk_get_rate(cpuclk->alt_parent);

	alt_prate = clk_get_rate(cpuclk->alt_parent);





	spin_lock(cpuclk->lock);

	spin_lock_irqsave(cpuclk->lock, flags);





	/*

	/*

	 * If the old parent clock speed is less than the clock speed

	 * If the old parent clock speed is less than the clock speed
@@ -164,7 +165,7 @@ static int rockchip_cpuclk_pre_rate_change(struct rockchip_cpuclk *cpuclk, 
			cpuclk->reg_base + reg_data->core_reg);

			cpuclk->reg_base + reg_data->core_reg);

	}

	}





	spin_unlock(cpuclk->lock);

	spin_unlock_irqrestore(cpuclk->lock, flags);

	return 0;

	return 0;

}

}
@@ -173,6 +174,7 @@ static int rockchip_cpuclk_post_rate_change(struct rockchip_cpuclk *cpuclk, 
{

{

	const struct rockchip_cpuclk_reg_data *reg_data = cpuclk->reg_data;

	const struct rockchip_cpuclk_reg_data *reg_data = cpuclk->reg_data;

	const struct rockchip_cpuclk_rate_table *rate;

	const struct rockchip_cpuclk_rate_table *rate;

	unsigned long flags;





	rate = rockchip_get_cpuclk_settings(cpuclk, ndata->new_rate);

	rate = rockchip_get_cpuclk_settings(cpuclk, ndata->new_rate);

	if (!rate) {

	if (!rate) {
@@ -181,7 +183,7 @@ static int rockchip_cpuclk_post_rate_change(struct rockchip_cpuclk *cpuclk, 
		return -EINVAL;

		return -EINVAL;

	}

	}





	spin_lock(cpuclk->lock);

	spin_lock_irqsave(cpuclk->lock, flags);





	if (ndata->old_rate < ndata->new_rate)

	if (ndata->old_rate < ndata->new_rate)

		rockchip_cpuclk_set_dividers(cpuclk, rate);

		rockchip_cpuclk_set_dividers(cpuclk, rate);
@@ -201,7 +203,7 @@ static int rockchip_cpuclk_post_rate_change(struct rockchip_cpuclk *cpuclk, 
	if (ndata->old_rate > ndata->new_rate)

	if (ndata->old_rate > ndata->new_rate)

		rockchip_cpuclk_set_dividers(cpuclk, rate);

		rockchip_cpuclk_set_dividers(cpuclk, rate);





	spin_unlock(cpuclk->lock);

	spin_unlock_irqrestore(cpuclk->lock, flags);

	return 0;

	return 0;

}

}