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

[Sibi Sankar <sibis@codeaurora.org>]

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.