linux-kernel - Re: [PATCH v2 2/3] ARM: imx: Add imx5 cpuidle driver

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Message-ID: <CAMXH7KE1jao1p5ZQ1aw8p7qzOQUftck22QTMKJ1oGwiPhY=FMA@mail.gmail.com>
Date:	Wed, 2 May 2012 15:11:35 -0500
From:	Rob Lee <rob.lee@...aro.org>
To:	Sascha Hauer <s.hauer@...gutronix.de>
Cc:	kernel@...gutronix.de, shawn.guo@...aro.org,
	amit.kucheria@...aro.org, daniel.lezcano@...aro.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linaro-dev@...ts.linaro.org, patches@...aro.org, jj@...osbits.net
Subject: Re: [PATCH v2 2/3] ARM: imx: Add imx5 cpuidle driver

Sascha,

On Wed, May 2, 2012 at 2:33 AM, Sascha Hauer <s.hauer@...gutronix.de> wrote:
> On Tue, May 01, 2012 at 09:12:39PM -0500, Robert Lee wrote:
>> Add imx5 cpuidle driver.
>>
>> Signed-off-by: Robert Lee <rob.lee@...aro.org>
>> ---
>>  arch/arm/mach-imx/mm-imx5.c |   42 +++++++++++++++++++++++++++++++++++++++---
>>  1 file changed, 39 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/arm/mach-imx/mm-imx5.c b/arch/arm/mach-imx/mm-imx5.c
>> index d6b7e9f..cbd9bad 100644
>> --- a/arch/arm/mach-imx/mm-imx5.c
>> +++ b/arch/arm/mach-imx/mm-imx5.c
>> @@ -22,24 +22,59 @@
>>  #include <mach/common.h>
>>  #include <mach/devices-common.h>
>>  #include <mach/iomux-v3.h>
>> +#include <mach/cpuidle.h>
>>
>>  static struct clk *gpc_dvfs_clk;
>>
>> -static void imx5_idle(void)
>> +static int imx5_idle(void)
>>  {
>> +     int ret = 0;
>> +
>>       /* gpc clock is needed for SRPG */
>>       if (gpc_dvfs_clk == NULL) {
>>               gpc_dvfs_clk = clk_get(NULL, "gpc_dvfs");
>>               if (IS_ERR(gpc_dvfs_clk))
>> -                     return;
>> +                     return -ENODEV;
>>       }
>>       clk_enable(gpc_dvfs_clk);
>>       mx5_cpu_lp_set(WAIT_UNCLOCKED_POWER_OFF);
>>       if (!tzic_enable_wake())
>>               cpu_do_idle();
>> +     else
>> +             ret = -EBUSY;
>>       clk_disable(gpc_dvfs_clk);
>> +
>> +     return ret;
>> +}
>> +
>> +static int imx5_cpuidle_enter(struct cpuidle_device *dev,
>> +                             struct cpuidle_driver *drv, int idx)
>> +{
>> +     int ret;
>> +
>> +     ret = imx5_idle();
>> +
>> +     if (ret < 0)
>> +             return ret;
>> +
>> +     return idx;
>>  }
>>
>> +static struct cpuidle_driver imx5_cpuidle_driver = {
>> +     .name                   = "imx5_cpuidle",
>> +     .owner                  = THIS_MODULE,
>> +     .en_core_tk_irqen       = 1,
>> +     .states[0]      = {
>> +             .enter                  = imx5_cpuidle_enter,
>> +             .exit_latency           = 20, /* max latency at 160MHz */
>> +             .target_residency       = 1,
>> +             .flags                  = CPUIDLE_FLAG_TIME_VALID,
>> +             .name                   = "IMX5 SRPG",
>> +             .desc                   = "CPU state retained,powered off",
>> +     },
>> +     .state_count            = 1,
>> +};
>> +
>>  /*
>>   * Define the MX50 memory map.
>>   */
>> @@ -103,7 +138,7 @@ void __init imx51_init_early(void)
>>       mxc_set_cpu_type(MXC_CPU_MX51);
>>       mxc_iomux_v3_init(MX51_IO_ADDRESS(MX51_IOMUXC_BASE_ADDR));
>>       mxc_arch_reset_init(MX51_IO_ADDRESS(MX51_WDOG1_BASE_ADDR));
>> -     arm_pm_idle = imx5_idle;
>> +     arm_pm_idle = (void *)imx5_idle;
>
> I don't like this. It will cover all warnings when the prototype of
> arm_pm_idle changes in future. Better add a static void imx5_idle
> which calls a static int imx5_do_idle, then you have an idle function
> which returns an int.
>

What about using the following:

arm_pm_idle =  (void (*)(void))imx5_idle;

This will give warnings if arm_pm_idle prototype changes.

Thanks,
Rob

>>  }
>>
>>  void __init imx53_init_early(void)
>> @@ -238,4 +273,5 @@ void __init imx53_soc_init(void)
>>  void __init imx51_init_late(void)
>>  {
>>       mx51_neon_fixup();
>> +     imx_cpuidle_init(&imx5_cpuidle_driver);
>>  }
>> --
>> 1.7.10
>>
>>
>
> --
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