linux-kernel - Re: [PATCH v12 2/2] cpufreq: qcom-hw: Add support for QCOM cpufreq HW driver

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Message-ID: <154469510700.19322.7762676027024031719@swboyd.mtv.corp.google.com>
Date:   Thu, 13 Dec 2018 01:58:27 -0800
From:   Stephen Boyd <swboyd@...omium.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Taniya Das <tdas@...eaurora.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Cc:     Rajendra Nayak <rnayak@...eaurora.org>, devicetree@...r.kernel.org,
        robh@...nel.org, skannan@...eaurora.org,
        linux-arm-msm@...r.kernel.org, evgreen@...gle.com,
        Matthias Kaehlcke <mka@...omium.org>,
        Taniya Das <tdas@...eaurora.org>,
        Stephen Boyd <swboyd@...omium.org>
Subject: Re: [PATCH v12 2/2] cpufreq: qcom-hw: Add support for QCOM cpufreq HW driver

Quoting Taniya Das (2018-12-12 23:49:54)
> The CPUfreq HW present in some QCOM chipsets offloads the steps necessary
> for changing the frequency of CPUs. The driver implements the cpufreq
> driver interface for this hardware engine.
> 
> Signed-off-by: Saravana Kannan <skannan@...eaurora.org>
> Signed-off-by: Stephen Boyd <swboyd@...omium.org>
> Signed-off-by: Taniya Das <tdas@...eaurora.org>
> ---

Reviewed-by: Stephen Boyd <swboyd@...omium.org>

But I noticed that we don't release the I/O region anymore so hotplug
and replug of a whole clk domain fails. I guess devm_ioremap_resource()
was just too much magic so how about we downgrade to devm_ioremap()
instead?

BTW, Viresh, I see a lockdep splat when cpufreq_init returns an error
upon bringing the policy online the second time. I guess cpufreq_stats
aren't able to be freed from there because they take locks in different
order vs. the normal path?

-----8<-------
diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
index fce7a1162e87..0e1105151478 100644
--- a/drivers/cpufreq/qcom-cpufreq-hw.c
+++ b/drivers/cpufreq/qcom-cpufreq-hw.c
@@ -182,9 +182,12 @@ static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
 	index = args.args[0];
 
 	res = platform_get_resource(global_pdev, IORESOURCE_MEM, index);
-	base = devm_ioremap_resource(dev, res);
-	if (IS_ERR(base))
-		return PTR_ERR(base);
+	if (!res)
+		return -ENODEV;
+
+	base = devm_ioremap(dev, res->start, resource_size(res));
+	if (!base)
+		return -ENOMEM;
 
 	/* HW should be in enabled state to proceed */
 	if (!(readl_relaxed(base + REG_ENABLE) & 0x1)) {