[PATCH 0/2] clk: misc bits for 3.8

[PATCH 0/2] clk: misc bits for 3.8

[Mike Turquette]

Hi all,

Unless there are any objections I plan to add these patches to the
clk-next queue for 3.8.  If there is discussion of the first patch then
I'll hold off until it's ready.

Thanks,
Mike

Mike Turquette (2):
  clk: introduce optional disable_unused callback
  MAINTAINERS: bad email address for Mike Turquette

 MAINTAINERS                  |    1 -
 drivers/clk/clk.c            |   13 +++++++++++--
 include/linux/clk-provider.h |    6 ++++++
 3 files changed, 17 insertions(+), 3 deletions(-)

-- 
1.7.9.5

[PATCH 1/2] clk: introduce optional disable_unused callback

[Mike Turquette]

Some gate clocks have special needs which must be handled during the
disable-unused clocks sequence.  These needs might be driven by software
due to the fact that we're disabling a clock outside of the normal
clk_disable path and a clk's enable_count will not be accurate.  On the
other hand a specific hardware programming sequence might need to be
followed for this corner case.

This change is needed for the upcoming OMAP port to the common clock
framework.  Specifically, it is undesirable to treat the disable-unused
path identically to the normal clk_disable path since other software
layers are involved.  In this case OMAP's clockdomain code throws WARNs
and bails early due to the clock's enable_count being set to zero.  A
custom callback mitigates this problem nicely.

Cc: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
---
 drivers/clk/clk.c            |   13 +++++++++++--
 include/linux/clk-provider.h |    6 ++++++
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 9955ad7..251e45d 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -219,8 +219,17 @@ static void clk_disable_unused_subtree(struct clk *clk)
 	if (clk->flags & CLK_IGNORE_UNUSED)
 		goto unlock_out;
 
-	if (__clk_is_enabled(clk) && clk->ops->disable)
-		clk->ops->disable(clk->hw);
+	/*
+	 * some gate clocks have special needs during the disable-unused
+	 * sequence.  call .disable_unused if available, otherwise fall
+	 * back to .disable
+	 */
+	if (__clk_is_enabled(clk)) {
+		if (clk->ops->disable_unused)
+			clk->ops->disable_unused(clk->hw);
+		else if (clk->ops->disable)
+			clk->ops->disable(clk->hw);
+	}
 
 unlock_out:
 	spin_unlock_irqrestore(&enable_lock, flags);
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 3593a3c..1c94d18 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -57,6 +57,11 @@ struct clk_hw;
  * 		This function must not sleep. Optional, if this op is not
  * 		set then the enable count will be used.
  *
+ * @disable_unused: Disable the clock atomically.  Only called from
+ *		clk_disable_unused for gate clocks with special needs.
+ *		Called with enable_lock held.  This function must not
+ *		sleep.
+ *
  * @recalc_rate	Recalculate the rate of this clock, by querying hardware. The
  * 		parent rate is an input parameter.  It is up to the caller to
  * 		ensure that the prepare_mutex is held across this call.
@@ -106,6 +111,7 @@ struct clk_ops {
 	int		(*enable)(struct clk_hw *hw);
 	void		(*disable)(struct clk_hw *hw);
 	int		(*is_enabled)(struct clk_hw *hw);
+	void		(*disable_unused)(struct clk_hw *hw);
 	unsigned long	(*recalc_rate)(struct clk_hw *hw,
 					unsigned long parent_rate);
 	long		(*round_rate)(struct clk_hw *hw, unsigned long,
-- 
1.7.9.5

[PATCH 2/2] MAINTAINERS: bad email address for Mike Turquette

[Mike Turquette]

Signed-off-by: Mike Turquette <mturquette@linaro.org>
---
 MAINTAINERS |    1 -
 1 file changed, 1 deletion(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index 1fa9074..6d7295f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1986,7 +1986,6 @@ F:	fs/coda/
 F:	include/linux/coda*.h
 
 COMMON CLK FRAMEWORK
-M:	Mike Turquette <mturquette@ti.com>
 M:	Mike Turquette <mturquette@linaro.org>
 L:	linux-arm-kernel at lists.infradead.org (same as CLK API & CLKDEV)
 T:	git git://git.linaro.org/people/mturquette/linux.git
-- 
1.7.9.5

[PATCH 1/2] clk: introduce optional disable_unused callback

[Ulf Hansson]

On 4 December 2012 22:00, Mike Turquette <mturquette@linaro.org> wrote:
> Some gate clocks have special needs which must be handled during the
> disable-unused clocks sequence.  These needs might be driven by software
> due to the fact that we're disabling a clock outside of the normal
> clk_disable path and a clk's enable_count will not be accurate.  On the
> other hand a specific hardware programming sequence might need to be
> followed for this corner case.
>
> This change is needed for the upcoming OMAP port to the common clock
> framework.  Specifically, it is undesirable to treat the disable-unused
> path identically to the normal clk_disable path since other software
> layers are involved.  In this case OMAP's clockdomain code throws WARNs
> and bails early due to the clock's enable_count being set to zero.  A
> custom callback mitigates this problem nicely.
>
> Cc: Paul Walmsley <paul@pwsan.com>
> Signed-off-by: Mike Turquette <mturquette@linaro.org>
> ---
>  drivers/clk/clk.c            |   13 +++++++++++--
>  include/linux/clk-provider.h |    6 ++++++
>  2 files changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 9955ad7..251e45d 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -219,8 +219,17 @@ static void clk_disable_unused_subtree(struct clk *clk)
>         if (clk->flags & CLK_IGNORE_UNUSED)
>                 goto unlock_out;
>
> -       if (__clk_is_enabled(clk) && clk->ops->disable)
> -               clk->ops->disable(clk->hw);
> +       /*
> +        * some gate clocks have special needs during the disable-unused
> +        * sequence.  call .disable_unused if available, otherwise fall
> +        * back to .disable
> +        */
> +       if (__clk_is_enabled(clk)) {
> +               if (clk->ops->disable_unused)
> +                       clk->ops->disable_unused(clk->hw);
> +               else if (clk->ops->disable)
> +                       clk->ops->disable(clk->hw);
> +       }
>
>  unlock_out:
>         spin_unlock_irqrestore(&enable_lock, flags);
> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> index 3593a3c..1c94d18 100644
> --- a/include/linux/clk-provider.h
> +++ b/include/linux/clk-provider.h
> @@ -57,6 +57,11 @@ struct clk_hw;
>   *             This function must not sleep. Optional, if this op is not
>   *             set then the enable count will be used.
>   *
> + * @disable_unused: Disable the clock atomically.  Only called from
> + *             clk_disable_unused for gate clocks with special needs.
> + *             Called with enable_lock held.  This function must not
> + *             sleep.
> + *
>   * @recalc_rate        Recalculate the rate of this clock, by querying hardware. The
>   *             parent rate is an input parameter.  It is up to the caller to
>   *             ensure that the prepare_mutex is held across this call.
> @@ -106,6 +111,7 @@ struct clk_ops {
>         int             (*enable)(struct clk_hw *hw);
>         void            (*disable)(struct clk_hw *hw);
>         int             (*is_enabled)(struct clk_hw *hw);
> +       void            (*disable_unused)(struct clk_hw *hw);
>         unsigned long   (*recalc_rate)(struct clk_hw *hw,
>                                         unsigned long parent_rate);
>         long            (*round_rate)(struct clk_hw *hw, unsigned long,
> --
> 1.7.9.5
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Is there a need for updating the clk documentation around this?

Anyway, you have my:

Acked-by: Ulf Hansson <ulf.hansson@linaro.org>


Kind regards
Ulf Hansson

[PATCH 1/2] clk: introduce optional disable_unused callback

[Mike Turquette]

On Wed, Dec 5, 2012 at 8:13 AM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> On 4 December 2012 22:00, Mike Turquette <mturquette@linaro.org> wrote:
>> Some gate clocks have special needs which must be handled during the
>> disable-unused clocks sequence.  These needs might be driven by software
>> due to the fact that we're disabling a clock outside of the normal
>> clk_disable path and a clk's enable_count will not be accurate.  On the
>> other hand a specific hardware programming sequence might need to be
>> followed for this corner case.
>>
>> This change is needed for the upcoming OMAP port to the common clock
>> framework.  Specifically, it is undesirable to treat the disable-unused
>> path identically to the normal clk_disable path since other software
>> layers are involved.  In this case OMAP's clockdomain code throws WARNs
>> and bails early due to the clock's enable_count being set to zero.  A
>> custom callback mitigates this problem nicely.
>>
>> Cc: Paul Walmsley <paul@pwsan.com>
>> Signed-off-by: Mike Turquette <mturquette@linaro.org>
>> ---
>>  drivers/clk/clk.c            |   13 +++++++++++--
>>  include/linux/clk-provider.h |    6 ++++++
>>  2 files changed, 17 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
>> index 9955ad7..251e45d 100644
>> --- a/drivers/clk/clk.c
>> +++ b/drivers/clk/clk.c
>> @@ -219,8 +219,17 @@ static void clk_disable_unused_subtree(struct clk *clk)
>>         if (clk->flags & CLK_IGNORE_UNUSED)
>>                 goto unlock_out;
>>
>> -       if (__clk_is_enabled(clk) && clk->ops->disable)
>> -               clk->ops->disable(clk->hw);
>> +       /*
>> +        * some gate clocks have special needs during the disable-unused
>> +        * sequence.  call .disable_unused if available, otherwise fall
>> +        * back to .disable
>> +        */
>> +       if (__clk_is_enabled(clk)) {
>> +               if (clk->ops->disable_unused)
>> +                       clk->ops->disable_unused(clk->hw);
>> +               else if (clk->ops->disable)
>> +                       clk->ops->disable(clk->hw);
>> +       }
>>
>>  unlock_out:
>>         spin_unlock_irqrestore(&enable_lock, flags);
>> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
>> index 3593a3c..1c94d18 100644
>> --- a/include/linux/clk-provider.h
>> +++ b/include/linux/clk-provider.h
>> @@ -57,6 +57,11 @@ struct clk_hw;
>>   *             This function must not sleep. Optional, if this op is not
>>   *             set then the enable count will be used.
>>   *
>> + * @disable_unused: Disable the clock atomically.  Only called from
>> + *             clk_disable_unused for gate clocks with special needs.
>> + *             Called with enable_lock held.  This function must not
>> + *             sleep.
>> + *
>>   * @recalc_rate        Recalculate the rate of this clock, by querying hardware. The
>>   *             parent rate is an input parameter.  It is up to the caller to
>>   *             ensure that the prepare_mutex is held across this call.
>> @@ -106,6 +111,7 @@ struct clk_ops {
>>         int             (*enable)(struct clk_hw *hw);
>>         void            (*disable)(struct clk_hw *hw);
>>         int             (*is_enabled)(struct clk_hw *hw);
>> +       void            (*disable_unused)(struct clk_hw *hw);
>>         unsigned long   (*recalc_rate)(struct clk_hw *hw,
>>                                         unsigned long parent_rate);
>>         long            (*round_rate)(struct clk_hw *hw, unsigned long,
>> --
>> 1.7.9.5
>>
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel at lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
> Is there a need for updating the clk documentation around this?
>

I knew I was forgetting something.  The documentation needs a general
cleanup effort and this callback should not go undocumented for long.

> Anyway, you have my:
>
> Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
>

Thanks!

Regards,
Mike

>
> Kind regards
> Ulf Hansson

[PATCH 1/2] clk: introduce optional disable_unused callback

[Linus Walleij]

On Tue, Dec 4, 2012 at 10:00 PM, Mike Turquette <mturquette@linaro.org> wrote:

> Some gate clocks have special needs which must be handled during the
> disable-unused clocks sequence.  These needs might be driven by software
> due to the fact that we're disabling a clock outside of the normal
> clk_disable path and a clk's enable_count will not be accurate.  On the
> other hand a specific hardware programming sequence might need to be
> followed for this corner case.
>
> This change is needed for the upcoming OMAP port to the common clock
> framework.  Specifically, it is undesirable to treat the disable-unused
> path identically to the normal clk_disable path since other software
> layers are involved.  In this case OMAP's clockdomain code throws WARNs
> and bails early due to the clock's enable_count being set to zero.  A
> custom callback mitigates this problem nicely.
>
> Cc: Paul Walmsley <paul@pwsan.com>
> Signed-off-by: Mike Turquette <mturquette@linaro.org>

This semantic change:

> -       if (__clk_is_enabled(clk) && clk->ops->disable)
> -               clk->ops->disable(clk->hw);
> +       /*
> +        * some gate clocks have special needs during the disable-unused
> +        * sequence.  call .disable_unused if available, otherwise fall
> +        * back to .disable
> +        */
> +       if (__clk_is_enabled(clk)) {
> +               if (clk->ops->disable_unused)
> +                       clk->ops->disable_unused(clk->hw);
> +               else if (clk->ops->disable)
> +                       clk->ops->disable(clk->hw);
> +       }

Means that you should probably go into all drivers and set their
.disable_unused to point to the clk_disable() implentation. Something
like the below (untested, Signed-off-by: Linus Walleij
<linus.walleij@linaro.org>

diff --git a/drivers/clk/clk-u300.c b/drivers/clk/clk-u300.c
index a15f792..504abde 100644
--- a/drivers/clk/clk-u300.c
+++ b/drivers/clk/clk-u300.c
@@ -340,6 +340,7 @@ static const struct clk_ops syscon_clk_ops = {
 	.unprepare = syscon_clk_unprepare,
 	.enable = syscon_clk_enable,
 	.disable = syscon_clk_disable,
+	.disable_unused = syscon_clk_disable,
 	.is_enabled = syscon_clk_is_enabled,
 	.recalc_rate = syscon_clk_recalc_rate,
 	.round_rate = syscon_clk_round_rate,
diff --git a/drivers/clk/ux500/clk-prcc.c b/drivers/clk/ux500/clk-prcc.c
index 7eee7f7..1d3ff60 100644
--- a/drivers/clk/ux500/clk-prcc.c
+++ b/drivers/clk/ux500/clk-prcc.c
@@ -84,12 +84,14 @@ static int clk_prcc_is_enabled(struct clk_hw *hw)
 static struct clk_ops clk_prcc_pclk_ops = {
 	.enable = clk_prcc_pclk_enable,
 	.disable = clk_prcc_pclk_disable,
+	.disable_unused = clk_prcc_pclk_disable,
 	.is_enabled = clk_prcc_is_enabled,
 };

 static struct clk_ops clk_prcc_kclk_ops = {
 	.enable = clk_prcc_kclk_enable,
 	.disable = clk_prcc_kclk_disable,
+	.disable_unused = clk_prcc_kclk_disable,
 	.is_enabled = clk_prcc_is_enabled,
 };

diff --git a/drivers/clk/ux500/clk-prcmu.c b/drivers/clk/ux500/clk-prcmu.c
index 74faa7e..00498f2 100644
--- a/drivers/clk/ux500/clk-prcmu.c
+++ b/drivers/clk/ux500/clk-prcmu.c
@@ -172,6 +172,7 @@ static struct clk_ops clk_prcmu_scalable_ops = {
 	.unprepare = clk_prcmu_unprepare,
 	.enable = clk_prcmu_enable,
 	.disable = clk_prcmu_disable,
+	.disable_unused = clk_prcmu_disable,
 	.is_enabled = clk_prcmu_is_enabled,
 	.recalc_rate = clk_prcmu_recalc_rate,
 	.round_rate = clk_prcmu_round_rate,
@@ -183,6 +184,7 @@ static struct clk_ops clk_prcmu_gate_ops = {
 	.unprepare = clk_prcmu_unprepare,
 	.enable = clk_prcmu_enable,
 	.disable = clk_prcmu_disable,
+	.disable_unused = clk_prcmu_disable,
 	.is_enabled = clk_prcmu_is_enabled,
 	.recalc_rate = clk_prcmu_recalc_rate,
 };
@@ -204,6 +206,7 @@ static struct clk_ops clk_prcmu_opp_gate_ops = {
 	.unprepare = clk_prcmu_opp_unprepare,
 	.enable = clk_prcmu_enable,
 	.disable = clk_prcmu_disable,
+	.disable_unused = clk_prcmu_disable,
 	.is_enabled = clk_prcmu_is_enabled,
 	.recalc_rate = clk_prcmu_recalc_rate,
 };
@@ -213,6 +216,7 @@ static struct clk_ops clk_prcmu_opp_volt_scalable_ops = {
 	.unprepare = clk_prcmu_opp_volt_unprepare,
 	.enable = clk_prcmu_enable,
 	.disable = clk_prcmu_disable,
+	.disable_unused = clk_prcmu_disable,
 	.is_enabled = clk_prcmu_is_enabled,
 	.recalc_rate = clk_prcmu_recalc_rate,
 	.round_rate = clk_prcmu_round_rate,


Yours,
Linus Walleij

[PATCH 1/2] clk: introduce optional disable_unused callback

[Ulf Hansson]

On 6 December 2012 20:07, Linus Walleij <linus.walleij@linaro.org> wrote:
> On Tue, Dec 4, 2012 at 10:00 PM, Mike Turquette <mturquette@linaro.org> wrote:
>
>> Some gate clocks have special needs which must be handled during the
>> disable-unused clocks sequence.  These needs might be driven by software
>> due to the fact that we're disabling a clock outside of the normal
>> clk_disable path and a clk's enable_count will not be accurate.  On the
>> other hand a specific hardware programming sequence might need to be
>> followed for this corner case.
>>
>> This change is needed for the upcoming OMAP port to the common clock
>> framework.  Specifically, it is undesirable to treat the disable-unused
>> path identically to the normal clk_disable path since other software
>> layers are involved.  In this case OMAP's clockdomain code throws WARNs
>> and bails early due to the clock's enable_count being set to zero.  A
>> custom callback mitigates this problem nicely.
>>
>> Cc: Paul Walmsley <paul@pwsan.com>
>> Signed-off-by: Mike Turquette <mturquette@linaro.org>
>
> This semantic change:
>
>> -       if (__clk_is_enabled(clk) && clk->ops->disable)
>> -               clk->ops->disable(clk->hw);
>> +       /*
>> +        * some gate clocks have special needs during the disable-unused
>> +        * sequence.  call .disable_unused if available, otherwise fall
>> +        * back to .disable
>> +        */
>> +       if (__clk_is_enabled(clk)) {
>> +               if (clk->ops->disable_unused)
>> +                       clk->ops->disable_unused(clk->hw);
>> +               else if (clk->ops->disable)
>> +                       clk->ops->disable(clk->hw);
>> +       }
>
> Means that you should probably go into all drivers and set their
> .disable_unused to point to the clk_disable() implentation. Something
> like the below (untested, Signed-off-by: Linus Walleij
> <linus.walleij@linaro.org>
>
> diff --git a/drivers/clk/clk-u300.c b/drivers/clk/clk-u300.c
> index a15f792..504abde 100644
> --- a/drivers/clk/clk-u300.c
> +++ b/drivers/clk/clk-u300.c
> @@ -340,6 +340,7 @@ static const struct clk_ops syscon_clk_ops = {
>         .unprepare = syscon_clk_unprepare,
>         .enable = syscon_clk_enable,
>         .disable = syscon_clk_disable,
> +       .disable_unused = syscon_clk_disable,
>         .is_enabled = syscon_clk_is_enabled,
>         .recalc_rate = syscon_clk_recalc_rate,
>         .round_rate = syscon_clk_round_rate,
> diff --git a/drivers/clk/ux500/clk-prcc.c b/drivers/clk/ux500/clk-prcc.c
> index 7eee7f7..1d3ff60 100644
> --- a/drivers/clk/ux500/clk-prcc.c
> +++ b/drivers/clk/ux500/clk-prcc.c
> @@ -84,12 +84,14 @@ static int clk_prcc_is_enabled(struct clk_hw *hw)
>  static struct clk_ops clk_prcc_pclk_ops = {
>         .enable = clk_prcc_pclk_enable,
>         .disable = clk_prcc_pclk_disable,
> +       .disable_unused = clk_prcc_pclk_disable,
>         .is_enabled = clk_prcc_is_enabled,
>  };
>
>  static struct clk_ops clk_prcc_kclk_ops = {
>         .enable = clk_prcc_kclk_enable,
>         .disable = clk_prcc_kclk_disable,
> +       .disable_unused = clk_prcc_kclk_disable,
>         .is_enabled = clk_prcc_is_enabled,
>  };
>
> diff --git a/drivers/clk/ux500/clk-prcmu.c b/drivers/clk/ux500/clk-prcmu.c
> index 74faa7e..00498f2 100644
> --- a/drivers/clk/ux500/clk-prcmu.c
> +++ b/drivers/clk/ux500/clk-prcmu.c
> @@ -172,6 +172,7 @@ static struct clk_ops clk_prcmu_scalable_ops = {
>         .unprepare = clk_prcmu_unprepare,
>         .enable = clk_prcmu_enable,
>         .disable = clk_prcmu_disable,
> +       .disable_unused = clk_prcmu_disable,
>         .is_enabled = clk_prcmu_is_enabled,
>         .recalc_rate = clk_prcmu_recalc_rate,
>         .round_rate = clk_prcmu_round_rate,
> @@ -183,6 +184,7 @@ static struct clk_ops clk_prcmu_gate_ops = {
>         .unprepare = clk_prcmu_unprepare,
>         .enable = clk_prcmu_enable,
>         .disable = clk_prcmu_disable,
> +       .disable_unused = clk_prcmu_disable,
>         .is_enabled = clk_prcmu_is_enabled,
>         .recalc_rate = clk_prcmu_recalc_rate,
>  };
> @@ -204,6 +206,7 @@ static struct clk_ops clk_prcmu_opp_gate_ops = {
>         .unprepare = clk_prcmu_opp_unprepare,
>         .enable = clk_prcmu_enable,
>         .disable = clk_prcmu_disable,
> +       .disable_unused = clk_prcmu_disable,
>         .is_enabled = clk_prcmu_is_enabled,
>         .recalc_rate = clk_prcmu_recalc_rate,
>  };
> @@ -213,6 +216,7 @@ static struct clk_ops clk_prcmu_opp_volt_scalable_ops = {
>         .unprepare = clk_prcmu_opp_volt_unprepare,
>         .enable = clk_prcmu_enable,
>         .disable = clk_prcmu_disable,
> +       .disable_unused = clk_prcmu_disable,
>         .is_enabled = clk_prcmu_is_enabled,
>         .recalc_rate = clk_prcmu_recalc_rate,
>         .round_rate = clk_prcmu_round_rate,
>
>
> Yours,
> Linus Walleij
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

I am not sure such change is needed. It kind of depends on what Mike
decides to put in the clk documentation. :-)

According to commit msg, it seems like the .disable_unused function
will be optional and must only be implemented for those clks that has
has special issues to consider.

Kind regards
Ulf Hansson

[PATCH 1/2] clk: introduce optional disable_unused callback

[Mike Turquette]

On Thu, Dec 6, 2012 at 1:58 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> On 6 December 2012 20:07, Linus Walleij <linus.walleij@linaro.org> wrote:
>> On Tue, Dec 4, 2012 at 10:00 PM, Mike Turquette <mturquette@linaro.org> wrote:
>>
>>> Some gate clocks have special needs which must be handled during the
>>> disable-unused clocks sequence.  These needs might be driven by software
>>> due to the fact that we're disabling a clock outside of the normal
>>> clk_disable path and a clk's enable_count will not be accurate.  On the
>>> other hand a specific hardware programming sequence might need to be
>>> followed for this corner case.
>>>
>>> This change is needed for the upcoming OMAP port to the common clock
>>> framework.  Specifically, it is undesirable to treat the disable-unused
>>> path identically to the normal clk_disable path since other software
>>> layers are involved.  In this case OMAP's clockdomain code throws WARNs
>>> and bails early due to the clock's enable_count being set to zero.  A
>>> custom callback mitigates this problem nicely.
>>>
>>> Cc: Paul Walmsley <paul@pwsan.com>
>>> Signed-off-by: Mike Turquette <mturquette@linaro.org>
>>
>> This semantic change:
>>
>>> -       if (__clk_is_enabled(clk) && clk->ops->disable)
>>> -               clk->ops->disable(clk->hw);
>>> +       /*
>>> +        * some gate clocks have special needs during the disable-unused
>>> +        * sequence.  call .disable_unused if available, otherwise fall
>>> +        * back to .disable
>>> +        */
>>> +       if (__clk_is_enabled(clk)) {
>>> +               if (clk->ops->disable_unused)
>>> +                       clk->ops->disable_unused(clk->hw);
>>> +               else if (clk->ops->disable)
>>> +                       clk->ops->disable(clk->hw);
>>> +       }
>>
>> Means that you should probably go into all drivers and set their
>> .disable_unused to point to the clk_disable() implentation. Something
>> like the below (untested, Signed-off-by: Linus Walleij
>> <linus.walleij@linaro.org>
>>
>> diff --git a/drivers/clk/clk-u300.c b/drivers/clk/clk-u300.c
>> index a15f792..504abde 100644
>> --- a/drivers/clk/clk-u300.c
>> +++ b/drivers/clk/clk-u300.c
>> @@ -340,6 +340,7 @@ static const struct clk_ops syscon_clk_ops = {
>>         .unprepare = syscon_clk_unprepare,
>>         .enable = syscon_clk_enable,
>>         .disable = syscon_clk_disable,
>> +       .disable_unused = syscon_clk_disable,
>>         .is_enabled = syscon_clk_is_enabled,
>>         .recalc_rate = syscon_clk_recalc_rate,
>>         .round_rate = syscon_clk_round_rate,
>> diff --git a/drivers/clk/ux500/clk-prcc.c b/drivers/clk/ux500/clk-prcc.c
>> index 7eee7f7..1d3ff60 100644
>> --- a/drivers/clk/ux500/clk-prcc.c
>> +++ b/drivers/clk/ux500/clk-prcc.c
>> @@ -84,12 +84,14 @@ static int clk_prcc_is_enabled(struct clk_hw *hw)
>>  static struct clk_ops clk_prcc_pclk_ops = {
>>         .enable = clk_prcc_pclk_enable,
>>         .disable = clk_prcc_pclk_disable,
>> +       .disable_unused = clk_prcc_pclk_disable,
>>         .is_enabled = clk_prcc_is_enabled,
>>  };
>>
>>  static struct clk_ops clk_prcc_kclk_ops = {
>>         .enable = clk_prcc_kclk_enable,
>>         .disable = clk_prcc_kclk_disable,
>> +       .disable_unused = clk_prcc_kclk_disable,
>>         .is_enabled = clk_prcc_is_enabled,
>>  };
>>
>> diff --git a/drivers/clk/ux500/clk-prcmu.c b/drivers/clk/ux500/clk-prcmu.c
>> index 74faa7e..00498f2 100644
>> --- a/drivers/clk/ux500/clk-prcmu.c
>> +++ b/drivers/clk/ux500/clk-prcmu.c
>> @@ -172,6 +172,7 @@ static struct clk_ops clk_prcmu_scalable_ops = {
>>         .unprepare = clk_prcmu_unprepare,
>>         .enable = clk_prcmu_enable,
>>         .disable = clk_prcmu_disable,
>> +       .disable_unused = clk_prcmu_disable,
>>         .is_enabled = clk_prcmu_is_enabled,
>>         .recalc_rate = clk_prcmu_recalc_rate,
>>         .round_rate = clk_prcmu_round_rate,
>> @@ -183,6 +184,7 @@ static struct clk_ops clk_prcmu_gate_ops = {
>>         .unprepare = clk_prcmu_unprepare,
>>         .enable = clk_prcmu_enable,
>>         .disable = clk_prcmu_disable,
>> +       .disable_unused = clk_prcmu_disable,
>>         .is_enabled = clk_prcmu_is_enabled,
>>         .recalc_rate = clk_prcmu_recalc_rate,
>>  };
>> @@ -204,6 +206,7 @@ static struct clk_ops clk_prcmu_opp_gate_ops = {
>>         .unprepare = clk_prcmu_opp_unprepare,
>>         .enable = clk_prcmu_enable,
>>         .disable = clk_prcmu_disable,
>> +       .disable_unused = clk_prcmu_disable,
>>         .is_enabled = clk_prcmu_is_enabled,
>>         .recalc_rate = clk_prcmu_recalc_rate,
>>  };
>> @@ -213,6 +216,7 @@ static struct clk_ops clk_prcmu_opp_volt_scalable_ops = {
>>         .unprepare = clk_prcmu_opp_volt_unprepare,
>>         .enable = clk_prcmu_enable,
>>         .disable = clk_prcmu_disable,
>> +       .disable_unused = clk_prcmu_disable,
>>         .is_enabled = clk_prcmu_is_enabled,
>>         .recalc_rate = clk_prcmu_recalc_rate,
>>         .round_rate = clk_prcmu_round_rate,
>>
>>
>> Yours,
>> Linus Walleij
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel at lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
> I am not sure such change is needed. It kind of depends on what Mike
> decides to put in the clk documentation. :-)
>
> According to commit msg, it seems like the .disable_unused function
> will be optional and must only be implemented for those clks that has
> has special issues to consider.
>

That is correct.  I don't want people to read the above code while
porting their platform and perceive that .disable_unused is mandatory
in any way.  Using the same function in both pointers defeats the
purpose of the new optional callback.

Regards,
Mike

> Kind regards
> Ulf Hansson

[PATCH 1/2] clk: introduce optional disable_unused callback

[Linus Walleij]

On Thu, Dec 6, 2012 at 11:05 PM, Mike Turquette <mturquette@linaro.org> wrote:
> On Thu, Dec 6, 2012 at 1:58 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:

>> According to commit msg, it seems like the .disable_unused function
>> will be optional and must only be implemented for those clks that has
>> has special issues to consider.
>>
>
> That is correct.  I don't want people to read the above code while
> porting their platform and perceive that .disable_unused is mandatory
> in any way.  Using the same function in both pointers defeats the
> purpose of the new optional callback.

Aha I get it...
Acked-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij