Re: [PATCH v5 1/8] drivers: kunit: Generic helpers for test device creation

From: Maxime Ripard <maxime@cerno.tech>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Matti Vaittinen <mazziesaccount@gmail.com>,
	Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Brendan Higgins <brendan.higgins@linux.dev>,
	David Gow <davidgow@google.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	kunit-dev@googlegroups.com, Stephen Boyd <sboyd@kernel.org>,
	Jonathan Cameron <jic23@kernel.org>,
	linux-iio@vger.kernel.org
Subject: Re: [PATCH v5 1/8] drivers: kunit: Generic helpers for test device creation
Date: Thu, 23 Mar 2023 11:12:16 +0100	[thread overview]
Message-ID: <20230323101216.w56kz3rudlj23vab@houat> (raw)
In-Reply-To: <ZBtPhoelZo4U5jwC@kroah.com>

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On Wed, Mar 22, 2023 at 07:57:10PM +0100, Greg Kroah-Hartman wrote:
> > > > +/**
> > > > + * test_kunit_helper_alloc_device - Allocate a mock device for a KUnit test
> > > > + * @test: The test context object
> > > > + *
> > > > + * This allocates a fake struct &device to create a mock for a KUnit
> > > > + * test. The device will also be bound to a fake driver. It will thus be
> > > > + * able to leverage the usual infrastructure and most notably the
> > > > + * device-managed resources just like a "real" device.
> > > 
> > > What specific "usual infrastructure" are you wanting to access here?
> > > 
> > > And again, if you want a fake device, make a virtual one, by just
> > > calling device_create().
> > > 
> > > Or are you wanting to do "more" with that device pointer than
> > > device_create() can give you?
> > 
> > Personally, I was (am) only interested in devm_ unwinding. I guess the
> > device_create(), device_add(), device_remove()... (didn't study this
> > sequence in details so sorry if there is errors) could've been sufficient
> > for me. I haven't looked how much of the code that there is for 'platform
> > devices' should be duplicated to support that sequence for testability
> > purposes.
> 
> Any device can access devm_ code, there's no need for it to be a
> platform device at all.

Sure but the resources are only released if the device is part of a bus,
so it can't be a root_device (or bare device) either

Maxime

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