Re: [PATCH v3 2/3] hwrng: add Rockchip SoC hwrng driver

Dragan Simic
2024-06-22T10:29:56Z

Hello Uwe,

On 2024-06-22 00:16, Uwe Kleine-König wrote:
> On 6/21/24 20:13, Dragan Simic wrote:
>> On 2024-06-21 11:57, Krzysztof Kozlowski wrote:
>>> On 21/06/2024 03:25, Daniel Golle wrote:
>>>> From: Aurelien Jarno <aurelien@aurel32.net>
>>
>> [snip]
>>
>>>> +    pm_runtime_set_autosuspend_delay(dev,
>>>> RK_RNG_AUTOSUSPEND_DELAY);
>>>> +    pm_runtime_use_autosuspend(dev);
>>>> +    pm_runtime_enable(dev);
>>>> +
>>>> +    ret = devm_hwrng_register(dev, &rk_rng->rng);
>>>> +    if (ret)
>>>> +        return dev_err_probe(&pdev->dev, ret, "Failed to register
>>>> Rockchip hwrng\n");
>>>> +
>>>> +    dev_info(&pdev->dev, "Registered Rockchip hwrng\n");
>>>
>>> Drop, driver should be silent on success.
>>
>> I respectfully disagree.  Many drivers print a single line upon
>> successful probing, which I find very useful.  In this particular
>> case, it's even more useful, because some people may be concerned
>> about the use of hardware TRNGs, so we should actually make sure
>> to announce it.
>
> I agree to Krzysztof here. From the POV of a driver author, your own
> driver is very important and while you write it, it really interests
> *you* if the driver is successfully probed. However from a system
> perspective these are annoying: There are easily >50 devices[1] on a
> system, if all of these print a message in probe, you have little
> chance
> to see the relevant messages. Even if every driver author thinks their
> work is a special snow flake that is worth announcing, in practice
> users
> only care about your driver if there is a problem. Additionally each
> message takes time and so delays the boot process. Additionally each
> message takes place in the printk ring buffer and so edges out earlier
> messages that might be more important.

Well, I don't find those messages annoying, for the drivers I've had
nothing to do with. Also, in my experience, 99.9% of users don't care
about the kernel messages at all, be it everything hunky-dory, or be
it something really wrong somewhere.

> So +1 for dropping the dev_info() or at least using dev_debug() for it.
>
> Best regards
> Uwe
>
> [1] On my laptop if have:
>
> $ find /sys/devices -name driver | wc -l
> 87
>
> On a Raspberrypi it yields 66.