The common clk framework is an attempt to define a common struct clk
which can be used by most platforms, and an API that drivers can always
use safely for managing clks.
The net result is consolidation of many different struct clk definitions
and platform-specific clk framework implementations.
On 11/21/2011 05:40 PM, Mike Turquette wrote:
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
new file mode 100644
index 000..12c9994
--- /dev/null
+++ b/drivers/clk/clk.c
@@ -0,0 +1,538 @@
+/*
+ * Copyright (C) 2010-2011 Canonical Ltd
+ * Copyright (C) 2011 Linaro Ltd
+ *
+ * This program
On Tue, Nov 22, 2011 at 7:12 PM, Saravana Kannan wrote:
> On 11/21/2011 05:40 PM, Mike Turquette wrote:
>> +void __clk_unprepare(struct clk *clk)
>> +{
>> + if (!clk)
>> + return;
>> +
>> + if (WARN_ON(clk->prepare_count == 0))
>> + return;
>> +
>> + i
On Mon, Nov 21, 2011 at 05:40:45PM -0800, Mike Turquette wrote:
[...]
> +/**
> + * DOC: Using the CLK_PARENT_SET_RATE flag
> + *
> + * __clk_set_rate changes the child's rate before the parent's to more
> + * easily handle failure conditions.
> + *
> + * This means clk might run out of spec for a s
On Sat, Nov 26, 2011 at 5:22 AM, Shawn Guo wrote:
> On Mon, Nov 21, 2011 at 05:40:45PM -0800, Mike Turquette wrote:
>> + * To prevent this consider setting the CLK_GATE_SET_RATE flag on any
>> + * clk where you also set the CLK_PARENT_SET_RATE flag
>
> Eh, this is how flag CLK_GATE_SET_RATE is bor
Hello,
Here are some initial comments on clk_get_rate().
On Mon, 21 Nov 2011, Mike Turquette wrote:
> +/**
> + * clk_get_rate - return the rate of clk
> + * @clk: the clk whose rate is being returned
> + *
> + * Simply returns the cached rate of the clk. Does not query the hardware.
> If
> +
Hi
a few initial comments on clk_get_parent().
On Mon, 21 Nov 2011, Mike Turquette wrote:
> +/**
> + * clk_get_parent - return the parent of a clk
> + * @clk: the clk whose parent gets returned
> + *
> + * Simply returns clk->parent. It is up to the caller to hold the
> + * prepare_lock, if des
On Wed, Nov 30, 2011 at 5:20 PM, Paul Walmsley wrote:
> This implementation of clk_get_rate() is racy, and is, in general, unsafe.
> The problem is that, in many cases, the clock's rate may change between
> the time that clk_get_rate() is called and the time that the returned
> rate is used. This
Hi Mike
a few brief comments.
On Wed, 30 Nov 2011, Turquette, Mike wrote:
> Likewise when a clk is requested to transition to a new frequency it
> will have to clear it with all of the clks below it, so there is still
> a need to propagate a request throughout the clk tree whenever
> clk_set_rat
On Wed, Nov 30, 2011 at 06:20:50PM -0700, Paul Walmsley wrote:
> 1. When a clock user calls clk_enable() on a clock, the clock framework
> should prevent other users of the clock from changing the clock's rate.
> This should persist until the clock user calls clk_disable() (but see also
> #2 be
On Wed, Nov 30, 2011 at 11:39:59PM -0700, Paul Walmsley wrote:
> Clock rate/parent-change notifiers are requirements for DVFS use-cases,
> and they must be paired with something like the
> clk_{allow,block}_rate_change() functions to work efficiently. I intend
> to comment on this later; it's
On Thu, Dec 1, 2011 at 6:42 AM, Mark Brown
wrote:
> On Wed, Nov 30, 2011 at 11:39:59PM -0700, Paul Walmsley wrote:
>
>> Clock rate/parent-change notifiers are requirements for DVFS use-cases,
>> and they must be paired with something like the
>> clk_{allow,block}_rate_change() functions to work ef
Hi Mark,
On Thu, 1 Dec 2011, Mark Brown wrote:
> On Wed, Nov 30, 2011 at 11:39:59PM -0700, Paul Walmsley wrote:
>
> > Clock rate/parent-change notifiers are requirements for DVFS use-cases,
> > and they must be paired with something like the
> > clk_{allow,block}_rate_change() functions to wor
On Thu, Dec 01, 2011 at 11:30:16AM -0700, Paul Walmsley wrote:
> So for example, if you had a driver that did:
> c = clk_get(dev, clk_name);
> clk_enable(c);
> clk_set_rate(c, clk_rate);
> and c was currently not enabled by any other driver on the system, and
> nothing else had called clk_block
On Thu, Dec 01, 2011 at 11:30:16AM -0700, Paul Walmsley wrote:
> The intention behind the clk_{allow,block}_rate_change() proposal was to
> allow the current user of the clock to change its rate without having to
> call clk_{allow,block}_rate_change(), if that driver was the sole user of
> the c
Hi Russell,
On Thu, 1 Dec 2011, Russell King - ARM Linux wrote:
> On Wed, Nov 30, 2011 at 06:20:50PM -0700, Paul Walmsley wrote:
> > 1. When a clock user calls clk_enable() on a clock, the clock framework
> > should prevent other users of the clock from changing the clock's rate.
> > This shou
On Fri, Dec 02, 2011 at 10:13:10AM -0700, Paul Walmsley wrote:
> Hi Russell,
>
> On Thu, 1 Dec 2011, Russell King - ARM Linux wrote:
>
> > On Wed, Nov 30, 2011 at 06:20:50PM -0700, Paul Walmsley wrote:
> > > 1. When a clock user calls clk_enable() on a clock, the clock framework
> > > should pre
Hello,
On Fri, Dec 02, 2011 at 08:23:06PM +, Russell King - ARM Linux wrote:
> On Fri, Dec 02, 2011 at 10:13:10AM -0700, Paul Walmsley wrote:
> > Hi Russell,
> >
> > On Thu, 1 Dec 2011, Russell King - ARM Linux wrote:
> >
> > > On Wed, Nov 30, 2011 at 06:20:50PM -0700, Paul Walmsley wrote:
>
On Thu, 1 Dec 2011, Russell King - ARM Linux wrote:
> On Thu, Dec 01, 2011 at 11:30:16AM -0700, Paul Walmsley wrote:
> > The intention behind the clk_{allow,block}_rate_change() proposal was to
> > allow the current user of the clock to change its rate without having to
> > call clk_{allow,block
Hi
a brief comment concerning clock rates:
On Mon, 21 Nov 2011, Mike Turquette wrote:
> +unsigned long clk_get_rate(struct clk *clk)
...
> +long clk_round_rate(struct clk *clk, unsigned long rate)
...
> +int clk_set_rate(struct clk *clk, unsigned long rate)
...
> +struct clk {
...
> +
On Mon, Nov 21, 2011 at 5:40 PM, Mike Turquette wrote:
> +/**
> + * clk_get_parent - return the parent of a clk
> + * @clk: the clk whose parent gets returned
> + *
> + * Simply returns clk->parent. It is up to the caller to hold the
> + * prepare_lock, if desired. Returns NULL if clk is NULL.
>
On Mon, Dec 05, 2011 at 02:15:56PM -0700, Paul Walmsley wrote:
> The types associated with clock rates in the clock interface
> (include/linux/clk.h) are inconsistent, and we should fix this.
Rubbish. They're different with good reason. Rates are primerily
unsigned quantities - and should be t
On Mon, 5 Dec 2011, Russell King - ARM Linux wrote:
> On Mon, Dec 05, 2011 at 02:15:56PM -0700, Paul Walmsley wrote:
>
> > But I'd propose that we instead increase the size of struct clk.rate to be
> > s64:
> >
> > s64 clk_round_rate(struct clk *clk, s64 desired_rate);
> > int clk_set_rate(struc
On Mon, 5 Dec 2011, Paul Walmsley wrote:
> For example, here's a trivial implementation for rate recalculation for a
> integer divider clock node (that can't be handled with a right shift):
>
> s64 div(struct clk *clk, u32 div) {
> if (clk->flags & CLK_PARENT_RATE_MAX_U32)
>
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