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Commit fc8726a2 authored by Dong Aisheng's avatar Dong Aisheng Committed by Stephen Boyd
Browse files

clk: core: support clocks which requires parents enable (part 2) 



On Freescale i.MX7D platform, all clocks operations, including
enable/disable, rate change and re-parent, requires its parent clock on.
Current clock core can not support it well.
This patch adding flag CLK_OPS_PARENT_ENABLE to handle this special case in
clock core that enable its parent clock firstly for each operation and
disable it later after operation complete.

The patch part 2 fixes set clock rate and set parent while its parent
is off. The most special case is for set_parent() operation which requires
all parents including both old and new one to be enabled at the same time
during the operation.

Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: default avatarDong Aisheng <aisheng.dong@nxp.com>
[sboyd@codeaurora.org: Move set_rate tracepoint after prepare_enable]
Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
parent a4b3518d

drivers/clk/clk.c

+33 −15
Original line number Diff line number Diff line
@@ -1172,7 +1172,9 @@ static struct clk_core *__clk_set_parent_before(struct clk_core *core, 
	struct clk_core *old_parent = core->parent;



	/*

	 * Migrate prepare state between parents and prevent race with

	 * 1. enable parents for CLK_OPS_PARENT_ENABLE clock

	 *

	 * 2. Migrate prepare state between parents and prevent race with

	 * clk_enable().

	 *

	 * If the clock is not prepared, then a race with
@@ -1188,12 +1190,17 @@ static struct clk_core *__clk_set_parent_before(struct clk_core *core, 
	 *

	 * See also: Comment for clk_set_parent() below.

	 */



	/* enable old_parent & parent if CLK_OPS_PARENT_ENABLE is set */

	if (core->flags & CLK_OPS_PARENT_ENABLE) {

		clk_core_prepare_enable(old_parent);

		clk_core_prepare_enable(parent);

	}



	/* migrate prepare count if > 0 */

	if (core->prepare_count) {

		clk_core_prepare(parent);

		flags = clk_enable_lock();

		clk_core_enable(parent);

		clk_core_enable(core);

		clk_enable_unlock(flags);

		clk_core_prepare_enable(parent);

		clk_core_enable_lock(core);

	}



	/* update the clk tree topology */
@@ -1208,18 +1215,19 @@ static void __clk_set_parent_after(struct clk_core *core, 
				   struct clk_core *parent,

				   struct clk_core *old_parent)

{

	unsigned long flags;



	/*

	 * Finish the migration of prepare state and undo the changes done

	 * for preventing a race with clk_enable().

	 */

	if (core->prepare_count) {

		flags = clk_enable_lock();

		clk_core_disable(core);

		clk_core_disable(old_parent);

		clk_enable_unlock(flags);

		clk_core_unprepare(old_parent);

		clk_core_disable_lock(core);

		clk_core_disable_unprepare(old_parent);

	}



	/* re-balance ref counting if CLK_OPS_PARENT_ENABLE is set */

	if (core->flags & CLK_OPS_PARENT_ENABLE) {

		clk_core_disable_unprepare(parent);

		clk_core_disable_unprepare(old_parent);

	}

}
@@ -1466,13 +1474,17 @@ static void clk_change_rate(struct clk_core *core) 
	unsigned long best_parent_rate = 0;

	bool skip_set_rate = false;

	struct clk_core *old_parent;

	struct clk_core *parent = NULL;



	old_rate = core->rate;



	if (core->new_parent)

	if (core->new_parent) {

		parent = core->new_parent;

		best_parent_rate = core->new_parent->rate;

	else if (core->parent)

	} else if (core->parent) {

		parent = core->parent;

		best_parent_rate = core->parent->rate;

	}



	if (core->flags & CLK_SET_RATE_UNGATE) {

		unsigned long flags;
@@ -1500,6 +1512,9 @@ static void clk_change_rate(struct clk_core *core) 
		__clk_set_parent_after(core, core->new_parent, old_parent);

	}



	if (core->flags & CLK_OPS_PARENT_ENABLE)

		clk_core_prepare_enable(parent);



	trace_clk_set_rate(core, core->new_rate);



	if (!skip_set_rate && core->ops->set_rate)
@@ -1518,6 +1533,9 @@ static void clk_change_rate(struct clk_core *core) 
		clk_core_unprepare(core);

	}



	if (core->flags & CLK_OPS_PARENT_ENABLE)

		clk_core_disable_unprepare(parent);



	if (core->notifier_count && old_rate != core->rate)

		__clk_notify(core, POST_RATE_CHANGE, old_rate, core->rate);