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From: Lina Iyer <lina.iyer@linaro.org>
To: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: khilman@linaro.org, sboyd@codeaurora.org, galak@codeaurora.org,
	linux-arm-msm@vger.kernel.org, linux-pm@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, lorenzo.pieralisi@arm.com,
	msivasub@codeaurora.org, devicetree@vger.kernel.org
Subject: Re: [PATCH v9 2/9] qcom: spm: Add Subsystem Power Manager driver
Date: Wed, 26 Nov 2014 08:22:06 -0700	[thread overview]
Message-ID: <20141126152206.GD594@linaro.org> (raw)
In-Reply-To: <20141126152003.GC594@linaro.org>

On Wed, Nov 26 2014 at 08:20 -0700, Lina Iyer wrote:
>On Wed, Nov 26 2014 at 04:19 -0700, Daniel Lezcano wrote:
>>On 11/19/2014 06:43 PM, Lina Iyer wrote:
>>>On Fri, Nov 14 2014 at 08:56 -0700, Daniel Lezcano wrote:
>>>>On 10/25/2014 01:40 AM, Lina Iyer wrote:
>>>
>>
>>>>>+
>>>>>+    if ((cpu > -1) && !cpuidle_drv_init) {
>>>>>+        platform_device_register(&qcom_cpuidle_device);
>>>>>+        cpuidle_drv_init = true;
>>>>>+    }
>>>>
>>>>'cpu' is always > -1.
>>>>
>>>OK. I was hoping to use -1 for not a cpu (i.e, L2) SPM. For now, I will
>>>change.
>>>
>>>
>>>>If the 'spm_get_drv' succeed, cpu is no longer equal to -EINVAL.
>>>>Otherwise we do not reach this point because we return right after
>>>>spm_get_drv with an error.
>>>>
>>>>Adding the platform_device_register depending in a static variable is
>>>>not very nice. Why not add it explicitely in a separate init routine
>>>>we know it will be called one time (eg. at the same place than cpufreq
>>>>is) ?
>>>>
>>>We want to register the cpuidle device only if any of the SPM devices
>>>have been probed.
>>>
>>>Ideally, Stephen and I would like to register cpuidle device separately
>>>for each CPU SPM, when it is probed, so we would invoke cpuidle driver
>>>and thereby the low power modes only for those cpus. However, the
>>>complexity to do that, AFAICS, is very complex. I would need to change
>>>quite a bit of the framework and in the cpuidle driver, I may have to
>>>stray from the recommended format.
>>>
>>>Here I set up cpuidle device, when I know atleast 1 cpu is ready to
>>>allow low power modes.
>>
>>Yes, instead of using the generic cpuidle_register function, you can 
>>use the low level functions for that.
>>
>>One call to cpuidle_register_driver in a single place and then 
>>cpuidle_register_device for each spm probe.
>>
>>Wouldn't make sense ?
>
>Yes, but there are some assumptions if we dont use
>MULTIPLE_CPUIDLE_DRIVERS like this -
>
>static void __cpuidle_driver_init(struct cpuidle_driver *drv)
>{
>       int i;
>	
>	drv->refcnt = 0; // Overwrites any cpuidle_driver_get()
>
>
>The clean way was to use MULTIPLE_CPUIDLE_DRIVERS, which seems like an
>incorrect use for this SoC.
>
Also, I probe and parse the cpuidle dt states for every SPM, which seems
redundant and any optimization looks as hackish as this check.

>Thanks,
>Lina

  reply	other threads:[~2014-11-26 15:22 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-10-24 23:40 [PATCH v9 0/9] cpuidle driver for QCOM SoCs: 8064, 8074, 8084 Lina Iyer
2014-10-24 23:40 ` [PATCH v9 1/9] qcom: scm: scm_set_warm_boot_addr() to set the warmboot address Lina Iyer
2014-11-14  8:30   ` Daniel Lezcano
2014-11-14 16:33     ` Lina Iyer
2014-10-24 23:40 ` [PATCH v9 2/9] qcom: spm: Add Subsystem Power Manager driver Lina Iyer
2014-11-14 15:56   ` Daniel Lezcano
2014-11-19 17:43     ` Lina Iyer
2014-11-26 11:19       ` Daniel Lezcano
2014-11-26 15:20         ` Lina Iyer
2014-11-26 15:22           ` Lina Iyer [this message]
2014-11-14 22:46   ` Stephen Boyd
2014-11-18 16:56     ` Lina Iyer
2014-11-18 20:28       ` Stephen Boyd
2014-11-17 21:32   ` Daniel Lezcano
2014-11-18 18:00     ` Lina Iyer
2014-11-18 19:39     ` Bjorn Andersson
2014-11-26 18:04   ` Kevin Hilman
2014-11-26 21:25     ` Daniel Lezcano
2014-10-24 23:40 ` [PATCH v9 3/9] arm: dts: qcom: Add power-controller device node for 8974 Krait CPUs Lina Iyer
2014-10-24 23:40 ` [PATCH v9 4/9] arm: dts: qcom: Add power-controller device node for 8084 " Lina Iyer
2014-10-24 23:40 ` [PATCH v9 5/9] arm: dts: qcom: Update power-controller device node for 8064 " Lina Iyer
2014-10-24 23:40 ` [PATCH v9 6/9] qcom: cpuidle: Add cpuidle driver for QCOM cpus Lina Iyer
2014-11-16 21:20   ` Daniel Lezcano
2014-11-17 18:30     ` Lina Iyer
2014-11-17 17:39   ` Lorenzo Pieralisi
2014-11-17 22:15     ` Lina Iyer
2014-10-24 23:40 ` [PATCH v9 7/9] arm: dts: qcom: Add idle states device nodes for 8974 Lina Iyer
2014-10-24 23:40 ` [PATCH v9 8/9] arm: dts: qcom: Add idle states device nodes for 8084 Lina Iyer
2014-10-24 23:40 ` [PATCH v9 9/9] arm: dts: qcom: Add idle state device nodes for 8064 Lina Iyer
2014-10-27  9:15 ` [PATCH v9 0/9] cpuidle driver for QCOM SoCs: 8064, 8074, 8084 Ivan T. Ivanov
2014-10-27 14:45   ` Lina Iyer
2014-11-13 20:25 ` Lina Iyer

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