linux-kernel - Re: [PATCH v5] cpuidle: sunplus: Create cpuidle driver for sunplus sp7021

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Message-ID: <748eb0e1-684c-a772-bccd-64b80780192f@kernel.org>
Date:   Tue, 1 Mar 2022 12:33:56 +0100
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Edwin Chiu 邱垂峰 <edwin.chiu@...plus.com>,
        Edwin Chiu <edwinchiu0505tw@...il.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "rafael@...nel.org" <rafael@...nel.org>,
        "daniel.lezcano@...aro.org" <daniel.lezcano@...aro.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v5] cpuidle: sunplus: Create cpuidle driver for sunplus
 sp7021

On 01/03/2022 10:30, Edwin Chiu 邱垂峰 wrote:
> 
> 
>> -----Original Message-----
>> From: Krzysztof Kozlowski <krzk@...nel.org>
>> Sent: Tuesday, February 22, 2022 12:48 AM
>> To: Edwin Chiu <edwinchiu0505tw@...il.com>; Edwin Chiu 邱垂峰 <edwin.chiu@...plus.com>;
>> robh+dt@...nel.org; devicetree@...r.kernel.org; linux-kernel@...r.kernel.org; rafael@...nel.org;
>> daniel.lezcano@...aro.org; linux-pm@...r.kernel.org
>> Subject: Re: [PATCH v5] cpuidle: sunplus: Create cpuidle driver for sunplus sp7021
>>
>> On 21/02/2022 08:26, Edwin Chiu wrote:
>>> Create cpuidle driver for sunplus sp7021 chip
>>>
>>> Signed-off-by: Edwin Chiu <edwinchiu0505tw@...il.com>
>>> ---
>>> Changes in v3
>>>  - Rearrangement #include sequence
>>>  - Change remark style to /*~*/
>>>  - Align author email address to same as sob
>>>  - Optimal code
>>> Changes in v4
>>>  - According Rob Herringrobh's comment
>>>    There is no need for this binding.
>>>    Just wanting a different driver is not a reason
>>>    for a duplicate schema.
>>>    So remove yaml file and submit driver again.
>>> Changes in v5
>>>  - According Krzysztof's comment
>>>    You either use appropriate compatible in DT
>>>    or add your compatible to cpuidle-arm.
>>>    Even if this did not work, then the solution is to
>>>    use common parts, not to duplicate entire driver.
>>>    According Sudeep's comment
>>>    In short NACK for any dedicated driver for this platform,
>>>    use the generic cpuidle-arm driver with appropriate platform hooks
>>>    Create cpuidle-sunplus.c in arch/arm/mach-sunplus/
>>>    for hook generic cpuidle-arm driver
>>>
>>>  MAINTAINERS                                   |  6 ++
>>>  arch/arm/mach-sunplus/cpuidle-sunplus.c       | 88 +++++++++++++++++
>>>  include/linux/platform_data/cpuidle-sunplus.h | 12 ++++
>>>  3 files changed, 106 insertions(+)
>>>  create mode 100644 arch/arm/mach-sunplus/cpuidle-sunplus.c
>>>  create mode 100644 include/linux/platform_data/cpuidle-sunplus.h
>>>
>>> diff --git a/MAINTAINERS b/MAINTAINERS index e0dca8f..5c96428 100644
>>> --- a/MAINTAINERS
>>> +++ b/MAINTAINERS
>>> @@ -18252,6 +18252,12 @@ L:	netdev@...r.kernel.org
>>>  S:	Maintained
>>>  F:	drivers/net/ethernet/dlink/sundance.c
>>>
>>> +SUNPLUS CPUIDLE DRIVER
>>> +M:	Edwin Chiu <edwinchiu0505tw@...il.com>
>>> +S:	Maintained
>>> +F:	arch/arm/mach-sunplus/cpuidle-sunplus.c
>>> +F:	include/linux/platform_data/cpuidle-sunplus.h
>>> +
>>>  SUPERH
>>>  M:	Yoshinori Sato <ysato@...rs.sourceforge.jp>
>>>  M:	Rich Felker <dalias@...c.org>
>>> diff --git a/arch/arm/mach-sunplus/cpuidle-sunplus.c
>>> b/arch/arm/mach-sunplus/cpuidle-sunplus.c
>>> new file mode 100644
>>> index 0000000..e9d9738
>>> --- /dev/null
>>> +++ b/arch/arm/mach-sunplus/cpuidle-sunplus.c
>>> @@ -0,0 +1,88 @@
>>> +// SPDX-License-Identifier: GPL-2.0-only
>>> +/*
>>> + * SP7021 cpu idle Driver.
>>> + * Copyright (C) Sunplus Tech / Tibbo Tech.
>>> + */
>>> +#define pr_fmt(fmt) "CPUidle arm: " fmt
>>> +
>>> +#include <linux/cpuidle.h>
>>> +#include <linux/of_device.h>
>>> +#include <linux/platform_data/cpuidle-sunplus.h>
>>> +
>>> +#include <asm/cpuidle.h>
>>> +
>>> +typedef int (*idle_fn)(void);
>>> +
>>> +static DEFINE_PER_CPU(idle_fn*, sp7021_idle_ops);
>>> +
>>> +static int sp7021_cpuidle_enter(unsigned long index) {
>>> +	return __this_cpu_read(sp7021_idle_ops)[index]();
>>> +}
>>> +static int sp7021_cpu_spc(void)
>>> +{
>>> +	cpu_v7_do_idle();   /* idle to WFI */
>>> +	return 0;
>>> +}
>>> +static const struct of_device_id sp7021_idle_state_match[] = {
>>> +	{ .compatible = "arm,idle-state", .data = sp7021_cpu_spc },
>>> +	{ },
>>> +};
>>
>> This is confusing. You want to have two drivers to bind to the same compatible? As I wrote in the
>> previous messages, you should simply use arm,idle-state just like few other architectures.
>>
>>
>> Best regards,
>> Krzysztof
> 
> 
> The patch v5 implemented according your comment.
> Used common part of arm,idle-state.
> Create new enable-method for cpuidle.ops function.
> It only have arm cpuidle driver exist now, no two drivers to bind to the same compatible.
> 
> What do you mean " simply use arm,idle-state just like few other architectures "?
>

I mean, do it similarly (by using arm,idle-state and other related
properties) to for example ti,am4372/ti,am3352.

Best regards,
Krzysztof