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Commit d9ba36b8 authored by Patrick Daly's avatar Patrick Daly
Browse files

qcom: clk: Support deferred clock initialization 



Clocks may depend on other clocks which are not registered yet. Handle
the error code -EPROBE_DEFER during clock initialization by placing
the offender on a clock orphan list, which will redo clock
initialization when another clock is registered successfully. Client
drivers may not obtain references to clocks on the orphan list.

Change-Id: I1a12feebe003884b775381d881e434bc9376f693
Signed-off-by: default avatarPatrick Daly <pdaly@codeaurora.org>
parent 3de56173

drivers/clk/qcom/clock.c

+36 −7
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ struct handoff_vdd { 
static LIST_HEAD(handoff_vdd_list);



static DEFINE_MUTEX(msm_clock_init_lock);

static LIST_HEAD(orphan_clk_list);



/* Find the voltage level required for a given rate. */

int find_vdd_level(struct clk *clk, unsigned long rate)
@@ -701,6 +702,9 @@ static int __handoff_clk(struct clk *clk) 
	if (clk->flags & CLKFLAG_INIT_ERR)

		return -ENXIO;



	if (clk->flags & CLKFLAG_EPROBE_DEFER)

		return -EPROBE_DEFER;



	/* Handoff any 'depends' clock first. */

	rc = __handoff_clk(clk->depends);

	if (rc)
@@ -761,6 +765,9 @@ static int __handoff_clk(struct clk *clk) 
	}



	clk->flags |= CLKFLAG_INIT_DONE;

	/* if the clk is on orphan list, remove it */

	list_del_init(&clk->list);

	clock_debug_register(clk);



	return 0;
@@ -768,8 +775,14 @@ err_depends: 
	clk_disable_unprepare(clk->parent);

err:

	kfree(h);

	clk->flags |= CLKFLAG_INIT_ERR;

	if (rc == -EPROBE_DEFER) {

		clk->flags |= CLKFLAG_EPROBE_DEFER;

		if (list_empty(&clk->list))

			list_add_tail(&clk->list, &orphan_clk_list);

	} else {

		pr_err("%s handoff failed (%d)\n", clk->dbg_name, rc);

		clk->flags |= CLKFLAG_INIT_ERR;

	}

	return rc;

}
@@ -783,7 +796,9 @@ err: 
 */

int msm_clock_register(struct clk_lookup *table, size_t size)

{

	int n = 0;

	int n = 0, rc;

	struct clk *c, *safe;

	bool found_more_clks;



	mutex_lock(&msm_clock_init_lock);
@@ -803,13 +818,27 @@ int msm_clock_register(struct clk_lookup *table, size_t size) 
	 * Detect and preserve initial clock state until clock_late_init() or

	 * a driver explicitly changes it, whichever is first.

	 */

	for (n = 0; n < size; n++) {



	for (n = 0; n < size; n++)

		__handoff_clk(table[n].clk);

		clock_debug_register(table[n].clk);

	}



	/* maintain backwards compatibility */

	if (table[0].con_id || table[0].dev_id)

		clkdev_add_table(table, size);



	do {

		found_more_clks = false;

		/* clear cached __handoff_clk return values */

		list_for_each_entry_safe(c, safe, &orphan_clk_list, list)

			c->flags &= ~CLKFLAG_EPROBE_DEFER;



		list_for_each_entry_safe(c, safe, &orphan_clk_list, list) {

			rc = __handoff_clk(c);

			if (!rc)

				found_more_clks = true;

		}

	} while (found_more_clks);



	mutex_unlock(&msm_clock_init_lock);



	return 0;

include/linux/clk/msm-clk.h

+1 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#define CLKFLAG_INIT_ERR		0x00002000

#define CLKFLAG_NO_RATE_CACHE		0x00004000

#define CLKFLAG_MEASURE			0x00008000

#define CLKFLAG_EPROBE_DEFER		0x00010000



struct clk_lookup;

struct clk;