linux-kernel - Re: [PATCH 1/2] clocksource: Add Ralink System Tick Counter driver

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Message-ID: <061c84bf-5e47-4ee8-9e78-40f0d4d02fd0@linaro.org>
Date: Mon, 28 Oct 2024 20:40:36 +0100
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Sergio Paracuellos <sergio.paracuellos@...il.com>
Cc: linux-mips@...r.kernel.org, tglx@...utronix.de,
 tsbogend@...ha.franken.de, john@...ozen.org, linux-kernel@...r.kernel.org,
 yangshiji66@...look.com
Subject: Re: [PATCH 1/2] clocksource: Add Ralink System Tick Counter driver

On 28/10/2024 20:02, Sergio Paracuellos wrote:
> Hi Daniel,
> 
> Thanks a lot for the detailed explanation. It was really helpful.
> 
> On Mon, Oct 28, 2024 at 7:44 PM Daniel Lezcano
> <daniel.lezcano@...aro.org> wrote:
>>
>> On 28/10/2024 19:04, Sergio Paracuellos wrote:
>>> Hi Daniel,
>>>
>>> Thanks for reviewing this.
>>>
>>> On Mon, Oct 28, 2024 at 5:29 PM Daniel Lezcano
>>> <daniel.lezcano@...aro.org> wrote:
>>>>
>>>> On 20/09/2024 09:53, Sergio Paracuellos wrote:
>>>>> System Tick Counter is present on Ralink SoCs RT3352 and MT7620. This
>>>>> driver has been in 'arch/mips/ralink' directory since the beggining of
>>>>> Ralink architecture support. However, it can be moved into a more proper
>>>>> place in 'drivers/clocksource'. Hence add it here adding also support for
>>>>> compile test targets.
>>>>>
>>>>> Signed-off-by: Sergio Paracuellos <sergio.paracuellos@...il.com>
>>>>> ---
>>>>>     drivers/clocksource/Kconfig        |  10 ++
>>>>>     drivers/clocksource/Makefile       |   1 +
>>>>>     drivers/clocksource/timer-ralink.c | 150 +++++++++++++++++++++++++++++
>>>>>     3 files changed, 161 insertions(+)
>>>>>     create mode 100644 drivers/clocksource/timer-ralink.c
>>>>>
>>>>> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
>>>>> index 95dd4660b5b6..50339f4d3201 100644
>>>>> --- a/drivers/clocksource/Kconfig
>>>>> +++ b/drivers/clocksource/Kconfig
>>>>> @@ -753,4 +753,14 @@ config EP93XX_TIMER
>>>>>           Enables support for the Cirrus Logic timer block
>>>>>           EP93XX.
>>>>>
>>>>> +config CLKSRC_RALINK
>>>>
>>>> It is a timer
>>>>
>>>>           RALINK_TIMER
>>>
>>> Sure, I will change to RALINK_TIMER instead.
>>>
>>>>
>>>>> +     bool "Ralink System Tick Counter"
>>>>
>>>> Silent option please if possible.
>>>>
>>>> Let the platform Kconfig selects the driver
>>>>
>>>>> +     depends on SOC_RT305X || SOC_MT7620 || COMPILE_TEST
>>>>> +     default y if SOC_RT305X || SOC_MT7620
>>>>
>>>> You should have something similar the RISCV option, no default option
>>>
>>> Sorry, I am not the best with Kconfig so I am not sure what you are
>>> exactly expecting here.MT7620
>>> Does the following work for you?
>>>
>>> config RALINK_TIMER
>>>      bool "Ralink System Tick Counter" if COMPILE_TEST
>>>      depends on SOC_RT305X || SOC_MT7620
>>>      select CLKSRC_MMIO
>>>      select TIMER_OF
>>>      help
>>>        Enables support for system tick counter present on
>>>        Ralink SoCs RT3352 and MT7620.
>>
>> Basically the idea is to have the platform's Kconfig selecting the
>> RALINK_TIMER. If I'm not wrong the Kconfig in arch/riscv/ralink should
>> select RALINK_TIMER under the "config SOC_RT305X" and "config
>> SOC_MT7620". The block "config CLKEVT_RT3352" has to be removed.
>>
>> Then this (clocksource) Kconfig option is a silent option. The user
>> won't have to figure out which option to enable because that will be
>> done directly when selecting RT305X or MT7620.
>>
>> The only reason to not have it silent is if you really want to opt-out
>> this timer because it is not present on a different version of RT305X or
>> MT7620.
> 
> Ok, then I don't want to silence it since those ralink's platform
> SOC_RT305X and SOC_MT7620 includes other SoCs models that do not have
> this timer (rt3050, mt7628 for example). Only models
> rt3352 and mt7620 include this. So I guess having this is the correct
> thing to do:
> 
> config RALINK_TIMER
>      bool "Ralink System Tick Counter" if COMPILE_TEST
>      depends on SOC_RT305X || SOC_MT7620
>      select CLKSRC_MMIO
>      select TIMER_OF
>      help
>         Enables support for system tick counter present on
>         Ralink SoCs RT3352 and MT7620.
> 
> Are you ok with this?


No because it is a compile test option only. You may want to do the same as:

https://lore.kernel.org/all/20241001-arm64-vexpress-sp804-v3-1-0a2d3f7883e4@kernel.org/

It should be:

config RALINK_TIMER
	bool "Ralink System Tick Counter"
	depends on SOC_RT305X || SOC_MT7620 || COMPILE_TEST
	select CLKSRC_MMIO
	select TIMER_OF
	help
	  Enables support for system tick counter present on
	  Ralink SoCs RT3352 and MT7620.

so very similar to the initial patch except no default is needed as it 
should be set from SOC_RT305X or SOC_MT7620


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