[ARM] omap: clk_set_parent: deny changing parent if clock is enabled (4da37821) · Commits · 戴 / test

Richard Woodruff writes: | The historic usage of this has been against single use leaf clocks | (1st instance of gptimer). When it was used it did: | clk_get() | clk_set_parent() | clk_enable() | | This usage was ok for that. Use on a disabled clock is needed. | | If there are multiple users on the clock or it is enabled there are | problems. | | The call can still be unfriendly if 2 different drivers are using the | clock with their own clock get/enable. It might be the function should | return an error if usecount != 0 to stop surprises. It is all around | better if the parenting is done when the clock is off. This is a good reason to ensure that the clock is not enabled when clk_set_parent() is called. Acked-by:

Richard Woodruff <r-woodruff2@ti.com> Signed-off-by:

Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-omap2/clock.c

+0 −6

Original line number	Diff line number	Diff line
		@@ -807,9 +807,6 @@ int omap2_clk_set_parent(struct clk clk, struct clk new_parent)
		if (!parent_div)
		return -EINVAL;

		if (clk->usecount > 0)
		_omap2_clk_disable(clk);

		/* Set new source value (previous dividers if any in effect) */
		v = __raw_readl(clk->clksel_reg);
		v &= ~clk->clksel_mask;
		@@ -819,9 +816,6 @@ int omap2_clk_set_parent(struct clk clk, struct clk new_parent)

		_omap2xxx_clk_commit(clk);

		if (clk->usecount > 0)
		_omap2_clk_enable(clk);

		clk_reparent(clk, new_parent);

		/* CLKSEL clocks follow their parents' rates, divided by a divisor */

arch/arm/plat-omap/clock.c

+10 −7

Original line number	Diff line number	Diff line
		@@ -144,6 +144,7 @@ int clk_set_parent(struct clk clk, struct clk parent)
		return ret;

		spin_lock_irqsave(&clockfw_lock, flags);
		if (clk->usecount == 0) {
		if (arch_clock->clk_set_parent)
		ret = arch_clock->clk_set_parent(clk, parent);
		if (ret == 0) {
		@@ -151,6 +152,8 @@ int clk_set_parent(struct clk clk, struct clk parent)
		clk->rate = clk->recalc(clk);
		propagate_rate(clk);
		}
		} else
		ret = -EBUSY;
		spin_unlock_irqrestore(&clockfw_lock, flags);

		return ret;

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