lkml.org 
[lkml]   [2012]   [Apr]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 1/3] ARM: imx: Add common imx cpuidle init functionality.
On Tue, Apr 17, 2012 at 2:43 AM, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> On Mon, Apr 16, 2012 at 06:50:12PM -0500, Robert Lee wrote:
>> Add common cpuidle init functionality that can be used by various
>> imx platforms.
>>
>> Signed-off-by: Robert Lee <rob.lee@linaro.org>
>> ---
>> diff --git a/arch/arm/plat-mxc/Makefile b/arch/arm/plat-mxc/Makefile
>> index e81290c..7c9e05f 100644
>> --- a/arch/arm/plat-mxc/Makefile
>> +++ b/arch/arm/plat-mxc/Makefile
>> @@ -16,6 +16,8 @@ obj-$(CONFIG_MXC_ULPI) += ulpi.o
>>  obj-$(CONFIG_MXC_USE_EPIT) += epit.o
>>  obj-$(CONFIG_MXC_DEBUG_BOARD) += 3ds_debugboard.o
>>  obj-$(CONFIG_CPU_FREQ_IMX)    += cpufreq.o
>> +obj-$(CONFIG_CPU_IDLE)    += cpuidle.o
>> +
>>  ifdef CONFIG_SND_IMX_SOC
>>  obj-y += ssi-fiq.o
>>  obj-y += ssi-fiq-ksym.o
>> diff --git a/arch/arm/plat-mxc/cpuidle.c b/arch/arm/plat-mxc/cpuidle.c
>> new file mode 100644
>> index 0000000..d1c9301
>> --- /dev/null
>> +++ b/arch/arm/plat-mxc/cpuidle.c
>> @@ -0,0 +1,89 @@
>> +/*
>> + * Copyright 2012 Freescale Semiconductor, Inc.
>> + * Copyright 2012 Linaro Ltd.
>> + *
>> + * The code contained herein is licensed under the GNU General Public
>> + * License. You may obtain a copy of the GNU General Public License
>> + * Version 2 or later at the following locations:
>> + *
>> + * http://www.opensource.org/licenses/gpl-license.html
>> + * http://www.gnu.org/copyleft/gpl.html
>> + */
>> +
>> +#include <linux/kernel.h>
>> +#include <linux/io.h>
>> +#include <linux/cpuidle.h>
>> +#include <linux/hrtimer.h>
>> +#include <linux/err.h>
>> +#include <linux/slab.h>
>> +
>> +static struct cpuidle_device __percpu * imx_cpuidle_devices;
>> +static struct cpuidle_driver *drv;
>> +
>> +void __init imx_cpuidle_set_driver(struct cpuidle_driver *p)
>> +{
>> +     drv = p;
>> +}
>
> You like it complicated, eh? Why do you introduce a function which sets
> a variable...
>

This complication is used to deal with the timing of various levels of
init calls. More explanation below.

>> +
>> +void imx_cpuidle_devices_uninit(void)
>> +{
>> +     int cpu_id;
>> +     struct cpuidle_device *dev;
>> +
>> +     for_each_possible_cpu(cpu_id) {
>> +             dev = per_cpu_ptr(imx_cpuidle_devices, cpu_id);
>> +             cpuidle_unregister_device(dev);
>> +     }
>> +
>> +     free_percpu(imx_cpuidle_devices);
>> +}
>> +
>> +static int __init imx_cpuidle_init(void)
>
> ... instead of passing it directly to the function which uses it?
>

If I called imx_cpuidle_init directly from imx5 or imx6q init
routines, it would be getting called before the coreinit_call of core
cpuidle causing a failure. There were various other directions to
take and all seemed less desirable than this one.

One alternative would be to add a function to return the pointer to
the cpuidle driver object based on the machine type. Functionality
exists to identify imx5 as a machine type but not imx6q, so I couldn't
use that machine based method without adding that extra code.

Another alternative would be to add a general platform lateinit_call
function to each platforms that support cpuidle.

>> +{
>> +     struct cpuidle_device *dev;
>> +     int cpu_id, ret;
>> +
>> +     if (!drv || drv->state_count > CPUIDLE_STATE_MAX) {
>> +             pr_err("%s: Invalid Input\n", __func__);
>
> You introduce a pointless error message on SoCs not setting a cpuidle
> driver. When will people learn that initcalls do not only run on
> machines they have on their desk?
>

Will fix in next version.

>> +             return -EINVAL;
>> +     }
>> +
>> +     ret = cpuidle_register_driver(drv);
>> +
>> +     if (ret) {
>> +             pr_err("%s: Failed to register cpuidle driver\n", __func__);
>
> It's always nice to add the return value to the error message to get a
> clue *what* went wrong. The function name though is rather
> uninteresting.

Will add the return value in the next version.

>
> Sascha
>
>
> --
> Pengutronix e.K.                           |                             |
> Industrial Linux Solutions                 | http://www.pengutronix.de/  |
> Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
> Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2012-04-17 15:57    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site