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FROMLIST: clk: adjust clocks to their requested rate after parent changes

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Given a hirarchy of clk1 -> [div] -> clk2, when the rate of clk1 gets
changed, clk2 changes as well as the divider stays the same. There may
be cases where a user of clk2 needs it at a specific rate, so clk2
needs to be readjusted for the changed rate of clk1.

So if a rate was requested for the clock, and its rate changed during
the underlying rate-change, with this change the clock framework now
tries to readjust the rate back to/near the requested one.

The whole process is protected by a new clock-flag to not force this
behaviour change onto every clock defined in the ccf.

(am from https://patchwork.kernel.org/patch/8993761/)

Change-Id: Ie2636710cb4e66815ee45b28ec86eeaaa47c55c7
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Xing Zheng <zhengxing@rock-chips.com>
Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>
This commit is contained in:
Heiko Stuebner
2016-05-02 18:36:21 +02:00
committed by Tao Huang
parent 679371c2f0
commit 12da448610
2 changed files with 12 additions and 1 deletions
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12
drivers/clk/clk.c
View File

@@ -1753,6 +1753,9 @@ static struct clk_core *clk_propagate_rate_change(struct clk_core *core,
return fail_clk;
}
static int clk_core_set_rate_nolock(struct clk_core *core,
unsigned long req_rate);
/*
* walk down a subtree and set the new rates notifying the rate
* change on the way
@@ -1851,6 +1854,12 @@ static void clk_change_rate(struct clk_core *core)
if (core->new_child)
clk_change_rate(core->new_child);
/* handle a changed clock that needs to readjust its rate */
if (core->flags & CLK_KEEP_REQ_RATE && core->req_rate
&& core->new_rate != old_rate
&& core->new_rate != core->req_rate)
clk_core_set_rate_nolock(core, core->req_rate);
clk_pm_runtime_put(core);
}
@@ -1920,10 +1929,11 @@ static int clk_core_set_rate_nolock(struct clk_core *core,
goto err;
}
core->req_rate = req_rate;
/* change the rates */
clk_change_rate(top);
core->req_rate = req_rate;
err:
clk_pm_runtime_put(core);

1
include/linux/clk-provider.h
View File

@@ -40,6 +40,7 @@
#define CLK_OPS_PARENT_ENABLE BIT(12)
/* duty cycle call may be forwarded to the parent clock */
#define CLK_DUTY_CYCLE_PARENT BIT(13)
#define CLK_KEEP_REQ_RATE BIT(14) /* keep reqrate on parent rate change */
struct clk;
struct clk_hw;