Re: [PATCH] clk: ti: Fix FAPLL udelay in clk_enable with clk_prepare

[Tony Lindgren]

* Peter Ujfalusi  [150922 23:17]:
> Tony,
> 
> On 09/23/2015 12:23 AM, Tony Lindgren wrote:
> > As recently pointed out (again) by Thomas and Russell, we must not
> > wait in in clk_enable. The wait for PLL to lock needs to happen
> > in clk_prepare instead.
> > 
> > It seems this is a common copy paste error with the PLL drivers,
> > and similar fixes should be applied to other PLL drivers after
> > testing.
> 
> One thing to note:
> because of how the hwmod code works, at boot time we prepare all clocks for
> the devices and in runtime the hwmod only uses clk_enable/disable, it will
> never unprepare the clock(s). This will means that these clocks will be
> enabled all the time and will never turned off.

Good point, we need to check that for hwmod pm_runtime related
functions. Basically the PLLs we can't disable until in
pm_runtime_disable.

I think the approach we need to take to be that clk_enable/disable
is really optional clk_gate_enable/disable. And in many cases PLLs
don't have a gate, so it's correct for pm_runtime enable/disable
to not do anything for the PLLs.

And the reason we don't want to change pm_runtime hooks to use
clk_prepare_enable/disable is that then drivers can't use
pm_runtime_irq_safe like some do currently.

Regards,

Tony
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Re: [PATCH] clk: ti: Fix FAPLL udelay in clk_enable with clk_prepare

[Peter Ujfalusi]

Tony,

On 09/23/2015 12:23 AM, Tony Lindgren wrote:
> As recently pointed out (again) by Thomas and Russell, we must not
> wait in in clk_enable. The wait for PLL to lock needs to happen
> in clk_prepare instead.
> 
> It seems this is a common copy paste error with the PLL drivers,
> and similar fixes should be applied to other PLL drivers after
> testing.

One thing to note:
because of how the hwmod code works, at boot time we prepare all clocks for
the devices and in runtime the hwmod only uses clk_enable/disable, it will
never unprepare the clock(s). This will means that these clocks will be
enabled all the time and will never turned off.

-- 
Péter

> Cc: Brian Hutchinson 
> Cc: Felipe Balbi 
> Cc: Grygorii Strashko 
> Cc: Nishanth Menon 
> Cc: Russell King - ARM Linux 
> Cc: Thomas Gleixner 
> Cc: Sekhar Nori 
> Signed-off-by: Tony Lindgren 
> ---
>  drivers/clk/ti/fapll.c | 18 +-
>  1 file changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/clk/ti/fapll.c b/drivers/clk/ti/fapll.c
> index f4b2e98..e1db74a 100644
> --- a/drivers/clk/ti/fapll.c
> +++ b/drivers/clk/ti/fapll.c
> @@ -37,7 +37,7 @@
>  #define FAPLL_PWD_OFFSET 4
>  
>  #define MAX_FAPLL_OUTPUTS7
> -#define FAPLL_MAX_RETRIES1000
> +#define FAPLL_MAX_RETRIES5
>  
>  #define to_fapll(_hw)container_of(_hw, struct fapll_data, hw)
>  #define to_synth(_hw)container_of(_hw, struct fapll_synth, 
> hw)
> @@ -126,7 +126,7 @@ static int ti_fapll_wait_lock(struct fapll_data *fd)
>   if (retries-- <= 0)
>   break;
>  
> - udelay(1);
> + usleep_range(200, 300);
>   }
>  
>   pr_err("%s failed to lock\n", fd->name);
> @@ -134,7 +134,7 @@ static int ti_fapll_wait_lock(struct fapll_data *fd)
>   return -ETIMEDOUT;
>  }
>  
> -static int ti_fapll_enable(struct clk_hw *hw)
> +static int ti_fapll_prepare(struct clk_hw *hw)
>  {
>   struct fapll_data *fd = to_fapll(hw);
>   u32 v = readl_relaxed(fd->base);
> @@ -146,7 +146,7 @@ static int ti_fapll_enable(struct clk_hw *hw)
>   return 0;
>  }
>  
> -static void ti_fapll_disable(struct clk_hw *hw)
> +static void ti_fapll_unprepare(struct clk_hw *hw)
>  {
>   struct fapll_data *fd = to_fapll(hw);
>   u32 v = readl_relaxed(fd->base);
> @@ -155,7 +155,7 @@ static void ti_fapll_disable(struct clk_hw *hw)
>   writel_relaxed(v, fd->base);
>  }
>  
> -static int ti_fapll_is_enabled(struct clk_hw *hw)
> +static int ti_fapll_is_prepared(struct clk_hw *hw)
>  {
>   struct fapll_data *fd = to_fapll(hw);
>   u32 v = readl_relaxed(fd->base);
> @@ -261,7 +261,7 @@ static int ti_fapll_set_rate(struct clk_hw *hw, unsigned 
> long rate,
>   v |= pre_div_p << FAPLL_MAIN_DIV_P_SHIFT;
>   v |= mult_n << FAPLL_MAIN_MULT_N_SHIFT;
>   writel_relaxed(v, fd->base);
> - if (ti_fapll_is_enabled(hw))
> + if (ti_fapll_is_prepared(hw))
>   ti_fapll_wait_lock(fd);
>   ti_fapll_clear_bypass(fd);
>  
> @@ -269,9 +269,9 @@ static int ti_fapll_set_rate(struct clk_hw *hw, unsigned 
> long rate,
>  }
>  
>  static struct clk_ops ti_fapll_ops = {
> - .enable = ti_fapll_enable,
> - .disable = ti_fapll_disable,
> - .is_enabled = ti_fapll_is_enabled,
> + .prepare = ti_fapll_prepare,
> + .unprepare = ti_fapll_unprepare,
> + .is_prepared = ti_fapll_is_prepared,
>   .recalc_rate = ti_fapll_recalc_rate,
>   .get_parent = ti_fapll_get_parent,
>   .round_rate = ti_fapll_round_rate,
> 


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Re: [PATCH] clk: ti: Fix FAPLL udelay in clk_enable with clk_prepare

[Russell King - ARM Linux]

On Tue, Sep 22, 2015 at 02:23:05PM -0700, Tony Lindgren wrote:
> As recently pointed out (again) by Thomas and Russell, we must not
> wait in in clk_enable. The wait for PLL to lock needs to happen
> in clk_prepare instead.
> 
> It seems this is a common copy paste error with the PLL drivers,
> and similar fixes should be applied to other PLL drivers after
> testing.
> 
> Cc: Brian Hutchinson 
> Cc: Felipe Balbi 
> Cc: Grygorii Strashko 
> Cc: Nishanth Menon 
> Cc: Russell King - ARM Linux 

As this moves things in the right direction (and only based on that):

Acked-by: Russell King 

> Cc: Thomas Gleixner 
> Cc: Sekhar Nori 
> Signed-off-by: Tony Lindgren 
> ---
>  drivers/clk/ti/fapll.c | 18 +-
>  1 file changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/clk/ti/fapll.c b/drivers/clk/ti/fapll.c
> index f4b2e98..e1db74a 100644
> --- a/drivers/clk/ti/fapll.c
> +++ b/drivers/clk/ti/fapll.c
> @@ -37,7 +37,7 @@
>  #define FAPLL_PWD_OFFSET 4
>  
>  #define MAX_FAPLL_OUTPUTS7
> -#define FAPLL_MAX_RETRIES1000
> +#define FAPLL_MAX_RETRIES5
>  
>  #define to_fapll(_hw)container_of(_hw, struct fapll_data, hw)
>  #define to_synth(_hw)container_of(_hw, struct fapll_synth, 
> hw)
> @@ -126,7 +126,7 @@ static int ti_fapll_wait_lock(struct fapll_data *fd)
>   if (retries-- <= 0)
>   break;
>  
> - udelay(1);
> + usleep_range(200, 300);
>   }
>  
>   pr_err("%s failed to lock\n", fd->name);
> @@ -134,7 +134,7 @@ static int ti_fapll_wait_lock(struct fapll_data *fd)
>   return -ETIMEDOUT;
>  }
>  
> -static int ti_fapll_enable(struct clk_hw *hw)
> +static int ti_fapll_prepare(struct clk_hw *hw)
>  {
>   struct fapll_data *fd = to_fapll(hw);
>   u32 v = readl_relaxed(fd->base);
> @@ -146,7 +146,7 @@ static int ti_fapll_enable(struct clk_hw *hw)
>   return 0;
>  }
>  
> -static void ti_fapll_disable(struct clk_hw *hw)
> +static void ti_fapll_unprepare(struct clk_hw *hw)
>  {
>   struct fapll_data *fd = to_fapll(hw);
>   u32 v = readl_relaxed(fd->base);
> @@ -155,7 +155,7 @@ static void ti_fapll_disable(struct clk_hw *hw)
>   writel_relaxed(v, fd->base);
>  }
>  
> -static int ti_fapll_is_enabled(struct clk_hw *hw)
> +static int ti_fapll_is_prepared(struct clk_hw *hw)
>  {
>   struct fapll_data *fd = to_fapll(hw);
>   u32 v = readl_relaxed(fd->base);
> @@ -261,7 +261,7 @@ static int ti_fapll_set_rate(struct clk_hw *hw, unsigned 
> long rate,
>   v |= pre_div_p << FAPLL_MAIN_DIV_P_SHIFT;
>   v |= mult_n << FAPLL_MAIN_MULT_N_SHIFT;
>   writel_relaxed(v, fd->base);
> - if (ti_fapll_is_enabled(hw))
> + if (ti_fapll_is_prepared(hw))
>   ti_fapll_wait_lock(fd);
>   ti_fapll_clear_bypass(fd);
>  
> @@ -269,9 +269,9 @@ static int ti_fapll_set_rate(struct clk_hw *hw, unsigned 
> long rate,
>  }
>  
>  static struct clk_ops ti_fapll_ops = {
> - .enable = ti_fapll_enable,
> - .disable = ti_fapll_disable,
> - .is_enabled = ti_fapll_is_enabled,
> + .prepare = ti_fapll_prepare,
> + .unprepare = ti_fapll_unprepare,
> + .is_prepared = ti_fapll_is_prepared,
>   .recalc_rate = ti_fapll_recalc_rate,
>   .get_parent = ti_fapll_get_parent,
>   .round_rate = ti_fapll_round_rate,
> -- 
> 2.1.4
> 

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[PATCH] clk: ti: Fix FAPLL udelay in clk_enable with clk_prepare

[Tony Lindgren]

As recently pointed out (again) by Thomas and Russell, we must not
wait in in clk_enable. The wait for PLL to lock needs to happen
in clk_prepare instead.

It seems this is a common copy paste error with the PLL drivers,
and similar fixes should be applied to other PLL drivers after
testing.

Cc: Brian Hutchinson 
Cc: Felipe Balbi 
Cc: Grygorii Strashko 
Cc: Nishanth Menon 
Cc: Russell King - ARM Linux 
Cc: Thomas Gleixner 
Cc: Sekhar Nori 
Signed-off-by: Tony Lindgren 
---
 drivers/clk/ti/fapll.c | 18 +-
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/clk/ti/fapll.c b/drivers/clk/ti/fapll.c
index f4b2e98..e1db74a 100644
--- a/drivers/clk/ti/fapll.c
+++ b/drivers/clk/ti/fapll.c
@@ -37,7 +37,7 @@
 #define FAPLL_PWD_OFFSET   4
 
 #define MAX_FAPLL_OUTPUTS  7
-#define FAPLL_MAX_RETRIES  1000
+#define FAPLL_MAX_RETRIES  5
 
 #define to_fapll(_hw)  container_of(_hw, struct fapll_data, hw)
 #define to_synth(_hw)  container_of(_hw, struct fapll_synth, hw)
@@ -126,7 +126,7 @@ static int ti_fapll_wait_lock(struct fapll_data *fd)
if (retries-- <= 0)
break;
 
-   udelay(1);
+   usleep_range(200, 300);
}
 
pr_err("%s failed to lock\n", fd->name);
@@ -134,7 +134,7 @@ static int ti_fapll_wait_lock(struct fapll_data *fd)
return -ETIMEDOUT;
 }
 
-static int ti_fapll_enable(struct clk_hw *hw)
+static int ti_fapll_prepare(struct clk_hw *hw)
 {
struct fapll_data *fd = to_fapll(hw);
u32 v = readl_relaxed(fd->base);
@@ -146,7 +146,7 @@ static int ti_fapll_enable(struct clk_hw *hw)
return 0;
 }
 
-static void ti_fapll_disable(struct clk_hw *hw)
+static void ti_fapll_unprepare(struct clk_hw *hw)
 {
struct fapll_data *fd = to_fapll(hw);
u32 v = readl_relaxed(fd->base);
@@ -155,7 +155,7 @@ static void ti_fapll_disable(struct clk_hw *hw)
writel_relaxed(v, fd->base);
 }
 
-static int ti_fapll_is_enabled(struct clk_hw *hw)
+static int ti_fapll_is_prepared(struct clk_hw *hw)
 {
struct fapll_data *fd = to_fapll(hw);
u32 v = readl_relaxed(fd->base);
@@ -261,7 +261,7 @@ static int ti_fapll_set_rate(struct clk_hw *hw, unsigned 
long rate,
v |= pre_div_p << FAPLL_MAIN_DIV_P_SHIFT;
v |= mult_n << FAPLL_MAIN_MULT_N_SHIFT;
writel_relaxed(v, fd->base);
-   if (ti_fapll_is_enabled(hw))
+   if (ti_fapll_is_prepared(hw))
ti_fapll_wait_lock(fd);
ti_fapll_clear_bypass(fd);
 
@@ -269,9 +269,9 @@ static int ti_fapll_set_rate(struct clk_hw *hw, unsigned 
long rate,
 }
 
 static struct clk_ops ti_fapll_ops = {
-   .enable = ti_fapll_enable,
-   .disable = ti_fapll_disable,
-   .is_enabled = ti_fapll_is_enabled,
+   .prepare = ti_fapll_prepare,
+   .unprepare = ti_fapll_unprepare,
+   .is_prepared = ti_fapll_is_prepared,
.recalc_rate = ti_fapll_recalc_rate,
.get_parent = ti_fapll_get_parent,
.round_rate = ti_fapll_round_rate,
-- 
2.1.4

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