[PATCH] opp: Fix dev_pm_opp_set_rate() to not return early

[PATCH] opp: Fix dev_pm_opp_set_rate() to not return early

[Rajendra Nayak]

dev_pm_opp_set_rate() can now be called with freq = 0 inorder
to either drop performance or bandwidth votes or to disable
regulators on platforms which support them.
In such cases, a subsequent call to dev_pm_opp_set_rate() with
the same frequency ends up returning early because 'old_freq == freq'
Instead make it fall through and put back the dropped performance
and bandwidth votes and/or enable back the regulators.

Fixes: cd7ea582 ("opp: Make dev_pm_opp_set_rate() handle freq = 0 to drop performance votes")
Reported-by: Sajida Bhanu <sbhanu@codeaurora.org>
Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
---
 drivers/opp/core.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 0c8c74a..a994f30 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -901,6 +901,9 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
 
 	/* Return early if nothing to do */
 	if (old_freq == freq) {
+		if (opp_table->required_opp_tables || opp_table->regulators ||
+		    opp_table->paths)
+			goto skip_clk_only;
 		dev_dbg(dev, "%s: old/new frequencies (%lu Hz) are same, nothing to do\n",
 			__func__, freq);
 		ret = 0;
@@ -919,6 +922,7 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
 		goto put_opp_table;
 	}
 
+skip_clk_only:
 	temp_freq = old_freq;
 	old_opp = _find_freq_ceil(opp_table, &temp_freq);
 	if (IS_ERR(old_opp)) {
@@ -954,8 +958,10 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
 						 IS_ERR(old_opp) ? NULL : old_opp->supplies,
 						 opp->supplies);
 	} else {
+		ret = 0;
 		/* Only frequency scaling */
-		ret = _generic_set_opp_clk_only(dev, clk, freq);
+		if (freq != old_freq)
+			ret = _generic_set_opp_clk_only(dev, clk, freq);
 	}
 
 	/* Scaling down? Configure required OPPs after frequency */
-- 
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation

Re: [PATCH] opp: Fix dev_pm_opp_set_rate() to not return early

[Sibi Sankar]

On 2020-08-10 12:36, Rajendra Nayak wrote:
> dev_pm_opp_set_rate() can now be called with freq = 0 inorder
> to either drop performance or bandwidth votes or to disable
> regulators on platforms which support them.
> In such cases, a subsequent call to dev_pm_opp_set_rate() with
> the same frequency ends up returning early because 'old_freq == freq'
> Instead make it fall through and put back the dropped performance
> and bandwidth votes and/or enable back the regulators.
> 
> Fixes: cd7ea582 ("opp: Make dev_pm_opp_set_rate() handle freq = 0 to
> drop performance votes")
> Reported-by: Sajida Bhanu <sbhanu@codeaurora.org>
> Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>

Reviewed-by: Sibi Sankar <sibis@codeaurora.org>

> ---
>  drivers/opp/core.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index 0c8c74a..a994f30 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -901,6 +901,9 @@ int dev_pm_opp_set_rate(struct device *dev,
> unsigned long target_freq)
> 
>  	/* Return early if nothing to do */
>  	if (old_freq == freq) {
> +		if (opp_table->required_opp_tables || opp_table->regulators ||
> +		    opp_table->paths)
> +			goto skip_clk_only;
>  		dev_dbg(dev, "%s: old/new frequencies (%lu Hz) are same, nothing to 
> do\n",
>  			__func__, freq);
>  		ret = 0;
> @@ -919,6 +922,7 @@ int dev_pm_opp_set_rate(struct device *dev,
> unsigned long target_freq)
>  		goto put_opp_table;
>  	}
> 
> +skip_clk_only:
>  	temp_freq = old_freq;
>  	old_opp = _find_freq_ceil(opp_table, &temp_freq);
>  	if (IS_ERR(old_opp)) {
> @@ -954,8 +958,10 @@ int dev_pm_opp_set_rate(struct device *dev,
> unsigned long target_freq)
>  						 IS_ERR(old_opp) ? NULL : old_opp->supplies,
>  						 opp->supplies);
>  	} else {
> +		ret = 0;
>  		/* Only frequency scaling */
> -		ret = _generic_set_opp_clk_only(dev, clk, freq);
> +		if (freq != old_freq)
> +			ret = _generic_set_opp_clk_only(dev, clk, freq);
>  	}
> 
>  	/* Scaling down? Configure required OPPs after frequency */

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project.

Re: [PATCH] opp: Fix dev_pm_opp_set_rate() to not return early

[Matthias Kaehlcke]

On Mon, Aug 10, 2020 at 12:36:19PM +0530, Rajendra Nayak wrote:
> dev_pm_opp_set_rate() can now be called with freq = 0 inorder
> to either drop performance or bandwidth votes or to disable
> regulators on platforms which support them.
> In such cases, a subsequent call to dev_pm_opp_set_rate() with
> the same frequency ends up returning early because 'old_freq == freq'
> Instead make it fall through and put back the dropped performance
> and bandwidth votes and/or enable back the regulators.
> 
> Fixes: cd7ea582 ("opp: Make dev_pm_opp_set_rate() handle freq = 0 to drop performance votes")
> Reported-by: Sajida Bhanu <sbhanu@codeaurora.org>
> Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>

Tested-by: Matthias Kaehlcke <mka@chromium.org>

Originally-reported-by: Matthias Kaehlcke <mka@chromium.org>
  https://patchwork.kernel.org/patch/11675369/#23514895 :P

Re: [PATCH] opp: Fix dev_pm_opp_set_rate() to not return early

[Rajendra Nayak]

On 8/11/2020 10:42 PM, Matthias Kaehlcke wrote:
> On Mon, Aug 10, 2020 at 12:36:19PM +0530, Rajendra Nayak wrote:
>> dev_pm_opp_set_rate() can now be called with freq = 0 inorder
>> to either drop performance or bandwidth votes or to disable
>> regulators on platforms which support them.
>> In such cases, a subsequent call to dev_pm_opp_set_rate() with
>> the same frequency ends up returning early because 'old_freq == freq'
>> Instead make it fall through and put back the dropped performance
>> and bandwidth votes and/or enable back the regulators.
>>
>> Fixes: cd7ea582 ("opp: Make dev_pm_opp_set_rate() handle freq = 0 to drop performance votes")
>> Reported-by: Sajida Bhanu <sbhanu@codeaurora.org>
>> Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
> 
> Tested-by: Matthias Kaehlcke <mka@chromium.org>
> 
> Originally-reported-by: Matthias Kaehlcke <mka@chromium.org>
>    https://patchwork.kernel.org/patch/11675369/#23514895 :P

Sorry to have missed that :/
Thanks for testing.

-- 
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation

Re: [PATCH] opp: Fix dev_pm_opp_set_rate() to not return early

[Stephen Boyd]

Quoting Rajendra Nayak (2020-08-10 00:06:19)
> dev_pm_opp_set_rate() can now be called with freq = 0 inorder
> to either drop performance or bandwidth votes or to disable
> regulators on platforms which support them.
> In such cases, a subsequent call to dev_pm_opp_set_rate() with
> the same frequency ends up returning early because 'old_freq == freq'
> Instead make it fall through and put back the dropped performance
> and bandwidth votes and/or enable back the regulators.
> 
> Fixes: cd7ea582 ("opp: Make dev_pm_opp_set_rate() handle freq = 0 to drop performance votes")
> Reported-by: Sajida Bhanu <sbhanu@codeaurora.org>
> Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
> ---
>  drivers/opp/core.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index 0c8c74a..a994f30 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -901,6 +901,9 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
>  
>         /* Return early if nothing to do */
>         if (old_freq == freq) {
> +               if (opp_table->required_opp_tables || opp_table->regulators ||
> +                   opp_table->paths)
> +                       goto skip_clk_only;

This is a goto maze! Any chance we can clean this up?

        if (!opp_table->required_opp_tables && !opp_table->regulators &&
	    !opp_table->paths)
	    if (old_freq == freq) {
		    ret = 0
		    dev_dbg(..)
	    } else if (!_get_opp_count(opp_table)) {
		    ret = _generic_set_opp_clk_only(dev, clk, freq);
	    }
	} else {
		temp_freq = old_freq;
		old_opp = _find_freq_ceil(opp_table, &temp_freq);
		...
	        dev_pm_opp_put(opp);
	put_old_opp:
		if (!IS_ERR(old_opp))
			dev_pm_opp_put(old_opp);
	}
put_opp_table:
	dev_pm_opp_put_opp_table(opp_table);

And that stuff in the else should probably go to another function.

>                 dev_dbg(dev, "%s: old/new frequencies (%lu Hz) are same, nothing to do\n",
>                         __func__, freq);
>                 ret = 0;
> @@ -919,6 +922,7 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
>                 goto put_opp_table;
>         }
>  
> +skip_clk_only:
>         temp_freq = old_freq;
>         old_opp = _find_freq_ceil(opp_table, &temp_freq);
>         if (IS_ERR(old_opp)) {
> @@ -954,8 +958,10 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
>                                                  IS_ERR(old_opp) ? NULL : old_opp->supplies,
>                                                  opp->supplies);
>         } else {
> +               ret = 0;
>                 /* Only frequency scaling */
> -               ret = _generic_set_opp_clk_only(dev, clk, freq);
> +               if (freq != old_freq)
> +                       ret = _generic_set_opp_clk_only(dev, clk, freq);
>         }

And write this as 

	else if (freq != old_freq) {
		ret = _generic_set_opp_clk_only(..)
	} else {
		ret = 0;
	}

Re: [PATCH] opp: Fix dev_pm_opp_set_rate() to not return early

[Viresh Kumar]

On 11-08-20, 14:09, Stephen Boyd wrote:
> This is a goto maze! Any chance we can clean this up?

I have sent a short series in reply to this series, please have a
look. It should look better now.

-- 
viresh

Re: [PATCH] opp: Fix dev_pm_opp_set_rate() to not return early

[Rajendra Nayak]

On 8/13/2020 9:59 AM, Viresh Kumar wrote:
> On 11-08-20, 14:09, Stephen Boyd wrote:
>> This is a goto maze! Any chance we can clean this up?
> 
> I have sent a short series in reply to this series, please have a
> look. It should look better now.

Thanks, I was out a few days so could not get to the cleanups
that Stephen was suggesting.
I will give your series a try.

-- 
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation