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 <mturque...@baylibre.com>
Cc: Stephen Boyd <sb...@codeaurora.org>
Cc: Shawn Guo <shawn...@kernel.org>
Signed-off-by: Dong Aisheng <aisheng.d...@nxp.com>
---
drivers/clk/clk.c | 52 +++++++++++++++++++++++++++++++++++-----------------
1 file changed, 35 insertions(+), 17 deletions(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index e3bd28c9ef28..f1f56158b8c7 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1172,7 +1172,7 @@ 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. Migrate prepare state between parents and prevent race with
* clk_enable().
*
* If the clock is not prepared, then a race with
@@ -1187,13 +1187,20 @@ static struct clk_core *__clk_set_parent_before(struct
clk_core *core,
* hardware and software states.
*
* See also: Comment for clk_set_parent() below.
+ *
+ * 2. enable parent clocks for CLK_OPS_PARENT_ENABLE clock
*/
+
+ /* 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 */
@@ -1208,19 +1215,20 @@ 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);
- }
+ if (core->prepare_count) {
+ 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);
+ }
+
}
static int __clk_set_parent(struct clk_core *core, struct clk_core *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;
@@ -1502,6 +1514,9 @@ static void clk_change_rate(struct clk_core *core)
trace_clk_set_rate(core, core->new_rate);
+ if (core->flags & CLK_OPS_PARENT_ON)
+ clk_core_prepare_enable(parent);
+
if (!skip_set_rate && core->ops->set_rate)
core->ops->set_rate(core->hw, core->new_rate, best_parent_rate);
@@ -1518,6 +1533,9 @@ static void clk_change_rate(struct clk_core *core)
clk_core_unprepare(core);
}
+ if (core->flags & CLK_OPS_PARENT_ON)
+ clk_core_disable_unprepare(parent);
+
if (core->notifier_count && old_rate != core->rate)
__clk_notify(core, POST_RATE_CHANGE, old_rate, core->rate);
--
1.9.1
