From: Vincent Whitchurch <vincent.whitchurch@axis.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Lee Jones <lee@kernel.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
kernel <kernel@axis.com>, <robh@kernel.org>
Subject: Re: [PATCH] mfd: Add Simple PCI MFD driver
Date: Wed, 25 Jan 2023 11:15:38 +0100 [thread overview]
Message-ID: <Y9EBSmOoE5+83jS5@axis.com> (raw)
In-Reply-To: <Y862WTT03/JxXUG8@kroah.com>
On Mon, Jan 23, 2023 at 05:31:21PM +0100, Greg Kroah-Hartman wrote:
> On Mon, Jan 23, 2023 at 03:32:55PM +0000, Lee Jones wrote:
> > On Mon, 23 Jan 2023, Vincent Whitchurch wrote:
> >
> > > Add a PCI driver which registers all child nodes specified in the
> > > devicetree. It will allow platform devices to be used on virtual
> > > systems which already support PCI and devicetree, such as UML with
> > > virt-pci.
> > >
> > > The driver has no id_table by default; user space needs to provide one
> > > using the new_id mechanism in sysfs.
> >
> > This feels wrong for several reasons.
> >
> > Firstly, I think Greg (Cc:ed) will have something to say about this.
>
> Yes, this isn't ok. Please write a real driver for the hardware under
> control here, and that would NOT be a MFD driver (hint, if you want to
> split up a PCI device into different drivers, use the aux bus code, that
> is what it is there for.)
I hope it's clear from my other replies in this thread that the entire
purpose of this driver is to allow arbitrary platform devices to be used
via a PCI device in virtual environments like User Mode Linux in order
to test existing platform drivers using mocked hardware.
Given this "hardware", it's not clear what a "real driver" would do
differently. The auxiliary bus cannot be used since it naturally does
not support platform devices. A hard coded list of sub-devices cannot
be used since arbitrary platform devices with arbitrary devicetree
properties need to be supported.
I could move this driver to drivers/bus/ and pitch it as a
"PCI<->platform bridge for testing in virtual environments", if that
makes more sense.
next prev parent reply other threads:[~2023-01-25 10:15 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-23 14:32 [PATCH] mfd: Add Simple PCI MFD driver Vincent Whitchurch
2023-01-23 15:32 ` Lee Jones
2023-01-23 16:02 ` Vincent Whitchurch
2023-01-23 16:36 ` Rob Herring
2023-01-24 2:30 ` Lizhi Hou
2023-01-24 13:15 ` Vincent Whitchurch
2023-01-23 16:31 ` Greg Kroah-Hartman
2023-01-25 10:15 ` Vincent Whitchurch [this message]
2023-01-25 12:29 ` Greg Kroah-Hartman
2023-01-25 13:06 ` Vincent Whitchurch
2023-01-25 13:34 ` Greg Kroah-Hartman
2023-01-25 14:54 ` Rob Herring
2023-01-25 15:00 ` Greg Kroah-Hartman
2023-01-25 15:34 ` Rob Herring
2023-01-31 15:07 ` Greg Kroah-Hartman
2023-01-23 16:13 ` Rob Herring
2023-01-24 12:54 ` Vincent Whitchurch
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