clk: fix CLK_SET_RATE_GATE with clock rate protection (9461f7b3) · Commits · 戴 / test

CLK_SET_RATE_GATE should prevent any operation which may result in a rate change or glitch while the clock is prepared/enabled. IOW, the following sequence is not allowed anymore with CLK_SET_RATE_GATE: * clk_get() * clk_prepare_enable() * clk_get_rate() * clk_set_rate() At the moment this is enforced on the leaf clock of the operation, not along the tree. This problematic because, if a PLL has the CLK_RATE_GATE, it won't be enforced if the clk_set_rate() is called on its child clocks. Using clock rate protection, we can now enforce CLK_SET_RATE_GATE along the clock tree Acked-by:

Linus Walleij <linus.walleij@linaro.org> Tested-by:

Quentin Schulz <quentin.schulz@free-electrons.com> Tested-by:

Maxime Ripard <maxime.ripard@free-electrons.com> Signed-off-by:

Jerome Brunet <jbrunet@baylibre.com> Signed-off-by:

Michael Turquette <mturquette@baylibre.com> Link: lkml.kernel.org/r/20180619134051.16726-3-jbrunet@baylibre.com

drivers/clk/clk.c

+13 −3

Original line number	Diff line number	Diff line
		@@ -691,6 +691,9 @@ static void clk_core_unprepare(struct clk_core *core)
		"Unpreparing critical %s\n", core->name))
		return;

		if (core->flags & CLK_SET_RATE_GATE)
		clk_core_rate_unprotect(core);

		if (--core->prepare_count > 0)
		return;

		@@ -765,6 +768,16 @@ static int clk_core_prepare(struct clk_core *core)

		core->prepare_count++;

		/*
		* CLK_SET_RATE_GATE is a special case of clock protection
		* Instead of a consumer claiming exclusive rate control, it is
		* actually the provider which prevents any consumer from making any
		* operation which could result in a rate change or rate glitch while
		* the clock is prepared.
		*/
		if (core->flags & CLK_SET_RATE_GATE)
		clk_core_rate_protect(core);

		return 0;
		unprepare:
		clk_core_unprepare(core->parent);
		@@ -1888,9 +1901,6 @@ static int clk_core_set_rate_nolock(struct clk_core *core,
		if (clk_core_rate_is_protected(core))
		return -EBUSY;

		if ((core->flags & CLK_SET_RATE_GATE) && core->prepare_count)
		return -EBUSY;

		/* calculate new rates and get the topmost changed clock */
		top = clk_calc_new_rates(core, req_rate);
		if (!top)

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