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

From: Taniya Das
Date: Thu Dec 13 2018 - 23:10:30 EST

Hello Stephen, Viresh,

On 12/13/2018 3:28 PM, Stephen Boyd wrote:
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@xxxxxxxxxxxxxx>
Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
Signed-off-by: Taniya Das <tdas@xxxxxxxxxxxxxx>

Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>

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()

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?

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;

Updated the above in the next series.

/* HW should be in enabled state to proceed */
if (!(readl_relaxed(base + REG_ENABLE) & 0x1)) {

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