Using clock rate protection, we can now enforce CLK_SET_RATE_GATE along the
clock tree

Acked-by: Linus Walleij <[email protected]>
Tested-by: Quentin Schulz <[email protected]>
Tested-by: Maxime Ripard <[email protected]>
Acked-by: Michael Turquette <[email protected]>
Signed-off-by: Jerome Brunet <[email protected]>
---
 drivers/clk/clk.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index f6fe5e5595ca..1af843ae20ff 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -605,6 +605,9 @@ static void clk_core_unprepare(struct clk_core *core)
        if (WARN_ON(core->prepare_count == 1 && core->flags & CLK_IS_CRITICAL))
                return;
 
+       if (core->flags & CLK_SET_RATE_GATE)
+               clk_core_rate_unprotect(core);
+
        if (--core->prepare_count > 0)
                return;
 
@@ -679,6 +682,16 @@ 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);
@@ -1780,9 +1793,6 @@ 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)
-- 
2.14.3

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