linux-kernel - Re: [PATCH] cpufreq: st: enable selective initialization based on the platform

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Message-ID: <20160427160746.GG4892@dell>
Date:	Wed, 27 Apr 2016 17:07:46 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Sudeep Holla <sudeep.holla@....com>
Cc:	linux-kernel@...r.kernel.org,
	Viresh Kumar <viresh.kumar@...aro.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>, linux-pm@...r.kernel.org
Subject: Re: [PATCH] cpufreq: st: enable selective initialization based on
 the platform

On Wed, 27 Apr 2016, Sudeep Holla wrote:

> The sti-cpufreq does unconditional registration of the cpufreq-dt driver
> which causes issue on an multi-platform build. For example, on Vexpress
> TC2 platform, we get the following error on boot:
> 
> cpu cpu0: OPP-v2 not supported
> cpu cpu0: Not doing voltage scaling
> cpu: dev_pm_opp_of_cpumask_add_table: couldn't find opp table
> 	for cpu:0, -19
> cpu cpu0: dev_pm_opp_get_max_volt_latency: Invalid regulator (-6)
> ...
> arm_big_little: bL_cpufreq_register: Failed registering platform driver:
> 		vexpress-spc, err: -17
> 
> The actual driver fails to initialise as cpufreq-dt is probed
> successfully, which is incorrect. This issue can happen to any platform
> not using cpufreq-dt in a multi-platform build.

Ah yes.  One of the pitfalls of not requiring platform registration.

> This patch adds a check to do selective initialization of the driver.
> 
> Cc: Lee Jones <lee.jones@...aro.org>
> Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
> Cc: Viresh Kumar <viresh.kumar@...aro.org>
> Cc: linux-pm@...r.kernel.org
> Fixes: ab0ea257fc58 ("cpufreq: st: Provide runtime initialised driver for ST's platforms")
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> ---
>  drivers/cpufreq/sti-cpufreq.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/cpufreq/sti-cpufreq.c b/drivers/cpufreq/sti-cpufreq.c
> index a9c659f58974..5fce58712a97 100644
> --- a/drivers/cpufreq/sti-cpufreq.c
> +++ b/drivers/cpufreq/sti-cpufreq.c
> @@ -259,6 +259,10 @@ static int sti_cpufreq_init(void)
>  {
>  	int ret;
>  
> +	if ((!of_machine_is_compatible("st,stih407-b2120")) &&
> +		(!of_machine_is_compatible("st,stih407")))
> +		return -ENODEV;

You need to check for "st,stih407" and "st,stih410".

>  	ddata.cpu = get_cpu_device(0);
>  	if (!ddata.cpu) {
>  		dev_err(ddata.cpu, "Failed to get device for CPU0\n");

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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