linux-kernel - Re: [PATCH v2 4/5] OPP: Update the bandwidth on OPP frequency changes

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Date:   Wed, 24 Apr 2019 15:35:01 +0530
From:   Sibi Sankar <sibis@...eaurora.org>
To:     Georgi Djakov <georgi.djakov@...aro.org>, vireshk@...nel.org,
        sboyd@...nel.org, nm@...com, robh+dt@...nel.org,
        mark.rutland@....com, rjw@...ysocki.net
Cc:     jcrouse@...eaurora.org, vincent.guittot@...aro.org,
        bjorn.andersson@...aro.org, amit.kucheria@...aro.org,
        seansw@....qualcomm.com, daidavid1@...eaurora.org,
        evgreen@...omium.org, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v2 4/5] OPP: Update the bandwidth on OPP frequency changes

Hey Georgi,

On 4/23/19 6:58 PM, Georgi Djakov wrote:
> If the OPP bandwidth values are populated, we want to switch also the
> interconnect bandwidth in addition to frequency and voltage.
> 
> Signed-off-by: Georgi Djakov <georgi.djakov@...aro.org>
> ---
>   drivers/opp/core.c | 9 ++++++++-
>   1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index 97ee39ecdebd..91d1c2abfb3e 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -707,7 +707,7 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
>   	unsigned long freq, old_freq;
>   	struct dev_pm_opp *old_opp, *opp;
>   	struct clk *clk;
> -	int ret;
> +	int ret, i;
>   
>   	if (unlikely(!target_freq)) {
>   		dev_err(dev, "%s: Invalid target frequency %lu\n", __func__,
> @@ -780,6 +780,13 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
>   		ret = _generic_set_opp_clk_only(dev, clk, freq);
>   	}
>   
> +	if (!ret && !IS_ERR_OR_NULL(opp_table->paths)) {
> +		for (i = 0; i < opp_table->path_count; i++) {
> +			icc_set_bw(opp_table->paths[i], opp->bandwidth[i].avg,
> +				   opp->bandwidth[i].peak);
> +		}
> +	}

An helper funcion dev_pm_opp_set_bw() would be needed by devices that
use alternative ways of scaling like "qcom-cpufreq-hw". I can probably
do that when I get ddr scaling working on sdm845 with your series.

> +
>   	/* Scaling down? Configure required OPPs after frequency */
>   	if (!ret && freq < old_freq) {
>   		ret = _set_required_opps(dev, opp_table, opp);
> 

-- 
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