linux-kernel - Re: [PATCH v4 5/7] cpufreq: qcom-hw: Implement CPRh aware OSM programming

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Message-ID: <20210420033743.cqfw7vb4zrewdsbl@vireshk-i7>
Date:   Tue, 20 Apr 2021 09:07:43 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...ainline.org>, agross@...nel.org,
        rjw@...ysocki.net, devicetree@...r.kernel.org, robh+dt@...nel.org,
        amit.kucheria@...aro.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, phone-devel@...r.kernel.org,
        konrad.dybcio@...ainline.org, marijn.suijten@...ainline.org,
        martin.botka@...ainline.org, jeffrey.l.hugo@...il.com
Subject: Re: [PATCH v4 5/7] cpufreq: qcom-hw: Implement CPRh aware OSM
 programming

On 19-04-21, 13:52, Bjorn Andersson wrote:
> On Tue 19 Jan 11:45 CST 2021, AngeloGioacchino Del Regno wrote:
> @Viresh, do you have any suggestion regarding my last comment?

> >  static int qcom_cpufreq_hw_driver_probe(struct platform_device *pdev)
> >  {
> > +	const struct qcom_cpufreq_soc_data *soc_data;
> > +	struct device_node *pd_node;
> > +	struct platform_device *pd_dev;
> >  	struct device *cpu_dev;
> >  	struct clk *clk;
> > -	int ret;
> > +	int clk_div, ret;
> > +
> > +	cpu_dev = get_cpu_device(0);
> > +	if (!cpu_dev)
> > +		return -EPROBE_DEFER;
> > +
> > +	soc_data = of_device_get_match_data(&pdev->dev);
> > +	if (!soc_data)
> > +		return -EINVAL;
> > +
> > +	if (!soc_data->uses_tz) {
> > +		/*
> > +		 * When the OSM is not pre-programmed from TZ, we will
> > +		 * need to program the sequencer through SCM calls.
> > +		 */
> > +		if (!qcom_scm_is_available())
> > +			return -EPROBE_DEFER;
> > +
> > +		/*
> > +		 * If there are no power-domains, OSM programming cannot be
> > +		 * performed, as in that case, we wouldn't know where to take
> > +		 * the params from...
> > +		 */
> > +		pd_node = of_parse_phandle(cpu_dev->of_node,
> > +					   "power-domains", 0);
> > +		if (!pd_node) {
> > +			ret = PTR_ERR(pd_node);
> > +			dev_err(cpu_dev, "power domain not found: %d\n", ret);
> > +			return ret;
> > +		}
> > +
> > +		/*
> > +		 * If the power domain device is not registered yet, then
> > +		 * defer probing this driver until that is available.
> > +		 */
> > +		pd_dev = of_find_device_by_node(pd_node);
> > +		if (!pd_dev || !pd_dev->dev.driver ||
> > +		    !device_is_bound(&pd_dev->dev))
> > +			return -EPROBE_DEFER;
> 
> I wonder if there's a more appropriate way to probe defer on resources
> described in the CPU nodes...

Recently we made some updates to the OPP core to start returning
EPROBE_DEFER on failure to acquire resources. I think you can get rid
of many checks for resources here by just trying to create the OPP
table and check its return value for EPROBE_DEFER.

-- 
viresh