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Date:   Tue, 03 Oct 2023 19:48:52 +0200
From:   "Arnd Bergmann" <arnd@arndb.de>
To:     "Alexander Graf" <graf@amazon.com>, linux-crypto@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org,
        "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
        "Herbert Xu" <herbert@gondor.apana.org.au>,
        "Olivia Mackall" <olivia@selenic.com>,
        "Petre Eftime" <petre.eftime@gmail.com>,
        "Erdem Meydanlli" <meydanli@amazon.nl>,
        "Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
        "David Woodhouse" <dwmw@amazon.co.uk>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        "Jason Wang" <jasowang@redhat.com>,
        "Xuan Zhuo" <xuanzhuo@linux.alibaba.com>
Subject: Re: [PATCH v2 1/2] misc: Add Nitro Secure Module driver
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On Fri, Sep 29, 2023, at 21:26, Alexander Graf wrote:
> On 29.09.23 19:28, Arnd Bergmann wrote:
>> On Fri, Sep 29, 2023, at 09:33, Alexander Graf wrote:

>>
>>> +int nsm_register_hwrng(struct nsm_hwrng *_nsm_hwrng)
>>> +{
>>> +     if (nsm_hwrng)
>>> +             return -EEXIST;
>>> +
>>> +     nsm_hwrng = _nsm_hwrng;
>>> +     if (nsm_vdev)
>>> +             nsm_hwrng->probe(nsm_vdev);
>>> +
>>> +     return 0;
>>> +}
>>> +EXPORT_SYMBOL_GPL(nsm_register_hwrng);
>> This should get easier of you reverse the dependency between
>> the two drivers and just call into the nsm_hwrng_probe()
>> function from the main driver's probe.
>
>
> I don't understand what you mean by reversing the dependency. Nsm_rng is 
> a downstream of Nsm, because Nsm is the virtio device that owns the channel.

To clarify: I don't really consider Nsm_rng as a downstream driver,
since the main driver does not have a bus model or device detection
below it that would allow probing any function specific drivers.

I would remove the dynamic registration entirely and just merge both
parts into a single file that happens to expose an rng interface.

     Arnd