linux-kernel - Re: [PATCH 2/3] clocksource/drivers/nxp-pit: Prevent driver unbind

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Message-ID: <a964500b-3363-456a-bfcc-38ec289cc57f@linaro.org>
Date: Wed, 12 Nov 2025 16:20:26 +0100
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Johan Hovold <johan@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>, Marc Zyngier <maz@...nel.org>,
 Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] clocksource/drivers/nxp-pit: Prevent driver unbind

On 11/12/25 12:01, Johan Hovold wrote:
> On Wed, Nov 12, 2025 at 11:00:05AM +0100, Daniel Lezcano wrote:
>> On 11/11/25 16:32, Johan Hovold wrote:
>>> The driver does not support unbinding (e.g. as clockevents cannot be
>>> deregistered) so suppress the bind attributes to prevent the driver from
>>> being unbound and rebound after registration (and disabling the timer
>>> when reprobing fails).
>>>
>>> Even if the driver can currently only be built-in, also switch to
>>> builtin_platform_driver() to prevent it from being unloaded should
>>> modular builds ever be enabled.
>>>
>>> Fixes: bee33f22d7c3 ("clocksource/drivers/nxp-pit: Add NXP Automotive s32g2 / s32g3 support")
>>> Signed-off-by: Johan Hovold <johan@...nel.org>
>>> ---
>>>    drivers/clocksource/timer-nxp-pit.c | 3 ++-
>>>    1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/clocksource/timer-nxp-pit.c b/drivers/clocksource/timer-nxp-pit.c
>>> index 2d0a3554b6bf..d1740f18f718 100644
>>> --- a/drivers/clocksource/timer-nxp-pit.c
>>> +++ b/drivers/clocksource/timer-nxp-pit.c
>>> @@ -374,9 +374,10 @@ static struct platform_driver nxp_pit_driver = {
>>>    	.driver = {
>>>    		.name = "nxp-pit",
>>>    		.of_match_table = pit_timer_of_match,
>>> +		.suppress_bind_attrs = true,
>>>    	},
>>>    	.probe = pit_timer_probe,
>>>    };
>>> -module_platform_driver(nxp_pit_driver);
>>> +builtin_platform_driver(nxp_pit_driver);
>>
>> Do not use builtin_platform here. You can add the tristate Kconfig
>> option for this driver, I tested it.
> 
> As I just commented on the cover letter, that's not relevant here;
> builtin_platform_driver() only prevents unloading a driver built as a
> module (which is something we want to prevent for these drivers).

I see your point, I agree. That is something we want to prevent for 
drivers having a clockevent.

Even if the core framework will prevent the module to be unloaded, we 
can consider these changes an additional guard.



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