linux-kernel - Re: [PATCH 1/3] crypto: exynos

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Date:   Thu, 07 Dec 2017 10:20:27 +0100
From:   Łukasz Stelmach <l.stelmach@...sung.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     robh+dt@...nel.org, Stephan Mueller <smueller@...onox.de>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Kukjin Kim <kgene@...nel.org>, linux-crypto@...r.kernel.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Bartłomiej Żołnierkiewicz 
        <b.zolnierkie@...sung.com>
Subject: Re: [PATCH 1/3] crypto: exynos - Support Exynos5250+ SoCs

It was <2017-12-06 śro 16:28>, when Krzysztof Kozlowski wrote:
> On Wed, Dec 6, 2017 at 3:53 PM, Łukasz Stelmach <l.stelmach@...sung.com> wrote:
>> It was <2017-12-06 śro 15:05>, when Krzysztof Kozlowski wrote:
>>> On Wed, Dec 6, 2017 at 2:42 PM, Łukasz Stelmach <l.stelmach@...sung.com> wrote:
>>>> It was <2017-12-05 wto 14:34>, when Krzysztof Kozlowski wrote:
>>>>> On Tue, Dec 5, 2017 at 1:35 PM, Łukasz Stelmach <l.stelmach@...sung.com> wrote:
>>>>>> Add support for PRNG in Exynos5250+ SoCs.
>>>>>>
>>>>>> Signed-off-by: Łukasz Stelmach <l.stelmach@...sung.com>
>>>>>> ---

[...]

>>>>>> +               dev_info(&pdev->dev,
>>>>>> +                        "Exynos Pseudo Random Number Generator (type:%d)\n",
>>>>>
>>>>> dev_dbg, this is not that important information to affect the boot time.
>>>>
>>>> Quite many devices report their presence during boot with such
>>>> messages. For example:
>>>>
>>>> [    3.390247] exynos-ehci 12110000.usb: EHCI Host Controller
>>>> [    3.395493] exynos-ehci 12110000.usb: new USB bus registered, assigned bus number 1
>>>> [    3.403702] exynos-ehci 12110000.usb: irq 80, io mem 0x12110000
>>>> [    3.431793] exynos-ehci 12110000.usb: USB 2.0 started, EHCI 1.00
>>>>
>>>> From my experience it isn't printk() itself that slows down boot but the
>>>> serial console.
>>>
>>> True, the console is bottleneck (not necessarily serial) [1] but that
>>> does not change the fact there is no need to print the type of RNG.
>>
>> With values of the enum not being meaningful themselves printing the
>> type does not make much sense for me too. Is it ok just to print report
>> the device presence?
>
> This does not change mine arguments - this printk does not bring any
> information except that there is such device. Later you might want to
> print this for Exynos TRNG. Later for other module, and other. Thus I
> prefer not to add it. On the other hand that is not a reason to stop
> this patch so for example you could split it into separate commit.

Done.

> It is kind of unrelated change and keeping it separate will not block
> everything if maintainer will not want it.

I will. As a user a prefer when devices report their presence in the log
buffer and I will submit such patch.

-- 
Łukasz Stelmach
Samsung R&D Institute Poland
Samsung Electronics

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