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

[Linus Walleij]

On Tue, Dec 4, 2012 at 10:00 PM, Mike Turquette <mturquette at 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 at pwsan.com>
> Signed-off-by: Mike Turquette <mturquette at 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 at 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