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From: Jason Gunthorpe <jgg@nvidia.com>
To: Mark Brown <broonie@kernel.org>
Cc: Greg KH <gregkh@linuxfoundation.org>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
	<alsa-devel@alsa-project.org>,
	Kiran Patil <kiran.patil@intel.com>,
	linux-rdma <linux-rdma@vger.kernel.org>,
	Shiraz Saleem <shiraz.saleem@intel.com>,
	Martin Habets <mhabets@solarflare.com>,
	"Liam Girdwood" <lgirdwood@gmail.com>,
	Ranjani Sridharan <ranjani.sridharan@linux.intel.com>,
	Fred Oh <fred.oh@linux.intel.com>,
	"Dave Ertman" <david.m.ertman@intel.com>,
	Jakub Kicinski <kuba@kernel.org>, Netdev <netdev@vger.kernel.org>,
	Leon Romanovsky <leonro@nvidia.com>,
	David Miller <davem@davemloft.net>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Parav Pandit <parav@mellanox.com>, <lee.jones@linaro.org>
Subject: Re: [resend/standalone PATCH v4] Add auxiliary bus support
Date: Fri, 18 Dec 2020 16:58:56 -0400	[thread overview]
Message-ID: <20201218205856.GZ552508@nvidia.com> (raw)
In-Reply-To: <20201218203211.GE5333@sirena.org.uk>

On Fri, Dec 18, 2020 at 08:32:11PM +0000, Mark Brown wrote:

> > So, I strongly suspect, MFD should create mfd devices on a MFD bus
> > type.
> 
> Historically people did try to create custom bus types, as I have
> pointed out before there was then pushback that these were duplicating
> the platform bus so everything uses platform bus.

Yes, I vaugely remember..

I don't know what to say, it seems Greg doesn't share this view of
platform devices as a universal device.

Reading between the lines, I suppose things would have been happier
with some kind of inheritance scheme where platform device remained as
only instantiated directly in board files, while drivers could bind to
OF/DT/ACPI/FPGA/etc device instantiations with minimal duplication &
boilerplate.

And maybe that is exactly what we have today with platform devices,
though the name is now unfortunate.

> I can't tell the difference between what it's doing and what SOF is
> doing, the code I've seen is just looking at the system it's running
> on and registering a fixed set of client devices.  It looks slightly
> different because it's registering a device at a time with some wrapper
> functions involved but that's what the code actually does.

SOF's aux bus usage in general seems weird to me, but if you think
it fits the mfd scheme of primarily describing HW to partition vs
describing a SW API then maybe it should use mfd.

The only problem with mfd as far as SOF is concerned was Greg was not
happy when he saw PCI stuff in the MFD subsystem.

This whole thing started when Intel first proposed to directly create
platform_device's in their ethernet driver and Greg had a quite strong
NAK to that.

MFD still doesn't fit what mlx5 and others in the netdev area are
trying to do. Though it could have been soe-horned it would have been
really weird to create a platform device with an empty HW resource
list. At a certain point the bus type has to mean *something*!

Jason

WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe <jgg@nvidia.com>
To: Mark Brown <broonie@kernel.org>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>,
	lee.jones@linaro.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Kiran Patil <kiran.patil@intel.com>,
	Liam Girdwood <lgirdwood@gmail.com>,
	linux-rdma <linux-rdma@vger.kernel.org>,
	Greg KH <gregkh@linuxfoundation.org>,
	Martin Habets <mhabets@solarflare.com>,
	alsa-devel@alsa-project.org,
	Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
	Fred Oh <fred.oh@linux.intel.com>,
	Netdev <netdev@vger.kernel.org>,
	Ranjani Sridharan <ranjani.sridharan@linux.intel.com>,
	Jakub Kicinski <kuba@kernel.org>,
	Dave Ertman <david.m.ertman@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Shiraz Saleem <shiraz.saleem@intel.com>,
	David Miller <davem@davemloft.net>,
	Leon Romanovsky <leonro@nvidia.com>,
	Parav Pandit <parav@mellanox.com>
Subject: Re: [resend/standalone PATCH v4] Add auxiliary bus support
Date: Fri, 18 Dec 2020 16:58:56 -0400	[thread overview]
Message-ID: <20201218205856.GZ552508@nvidia.com> (raw)
In-Reply-To: <20201218203211.GE5333@sirena.org.uk>

On Fri, Dec 18, 2020 at 08:32:11PM +0000, Mark Brown wrote:

> > So, I strongly suspect, MFD should create mfd devices on a MFD bus
> > type.
> 
> Historically people did try to create custom bus types, as I have
> pointed out before there was then pushback that these were duplicating
> the platform bus so everything uses platform bus.

Yes, I vaugely remember..

I don't know what to say, it seems Greg doesn't share this view of
platform devices as a universal device.

Reading between the lines, I suppose things would have been happier
with some kind of inheritance scheme where platform device remained as
only instantiated directly in board files, while drivers could bind to
OF/DT/ACPI/FPGA/etc device instantiations with minimal duplication &
boilerplate.

And maybe that is exactly what we have today with platform devices,
though the name is now unfortunate.

> I can't tell the difference between what it's doing and what SOF is
> doing, the code I've seen is just looking at the system it's running
> on and registering a fixed set of client devices.  It looks slightly
> different because it's registering a device at a time with some wrapper
> functions involved but that's what the code actually does.

SOF's aux bus usage in general seems weird to me, but if you think
it fits the mfd scheme of primarily describing HW to partition vs
describing a SW API then maybe it should use mfd.

The only problem with mfd as far as SOF is concerned was Greg was not
happy when he saw PCI stuff in the MFD subsystem.

This whole thing started when Intel first proposed to directly create
platform_device's in their ethernet driver and Greg had a quite strong
NAK to that.

MFD still doesn't fit what mlx5 and others in the netdev area are
trying to do. Though it could have been soe-horned it would have been
really weird to create a platform device with an empty HW resource
list. At a certain point the bus type has to mean *something*!

Jason

  reply	other threads:[~2020-12-18 21:00 UTC|newest]

Thread overview: 114+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-03  0:54 [resend/standalone PATCH v4] Add auxiliary bus support Dan Williams
2020-12-03  0:54 ` Dan Williams
2020-12-03 15:06 ` Greg KH
2020-12-03 15:06   ` Greg KH
2020-12-04  2:33   ` Jason Gunthorpe
2020-12-04  2:33     ` Jason Gunthorpe
2020-12-04  3:37     ` Dan Williams
2020-12-04  3:37       ` Dan Williams
2020-12-03 15:07 ` Greg KH
2020-12-03 15:07   ` Greg KH
2020-12-03 15:55   ` Leon Romanovsky
2020-12-03 15:55     ` Leon Romanovsky
2020-12-04 11:42 ` Greg KH
2020-12-04 11:42   ` Greg KH
2020-12-04 11:43   ` [PATCH 1/3] driver core: auxiliary bus: move slab.h from include file Greg KH
2020-12-04 11:43     ` Greg KH
2020-12-04 11:44     ` [PATCH 2/3] driver core: auxiliary bus: make remove function return void Greg KH
2020-12-04 11:44       ` Greg KH
2020-12-04 11:44       ` [PATCH 3/3] driver core: auxiliary bus: minor coding style tweaks Greg KH
2020-12-04 11:44         ` Greg KH
2020-12-04 11:48         ` Greg KH
2020-12-04 11:48           ` Greg KH
2020-12-04 11:49       ` [PATCH v2 " Greg KH
2020-12-04 11:49         ` Greg KH
2020-12-04 12:32   ` [resend/standalone PATCH v4] Add auxiliary bus support Leon Romanovsky
2020-12-04 12:32     ` Leon Romanovsky
2020-12-04 12:43     ` Parav Pandit
2020-12-04 12:43       ` Parav Pandit
2020-12-04 12:59     ` Greg KH
2020-12-04 12:59       ` Greg KH
2020-12-04 17:10       ` Ranjani Sridharan
2020-12-04 17:10         ` Ranjani Sridharan
2020-12-05  9:02         ` Greg KH
2020-12-05  9:02           ` Greg KH
2020-12-04 16:41   ` Dan Williams
2020-12-04 16:41     ` Dan Williams
2020-12-05 15:51     ` Greg KH
2020-12-05 15:51       ` Greg KH
2020-12-17 21:19       ` Alexandre Belloni
2020-12-17 21:19         ` Alexandre Belloni
2020-12-18  2:39         ` Dan Williams
2020-12-18  2:39           ` Dan Williams
2020-12-18 14:20           ` Mark Brown
2020-12-18 14:20             ` Mark Brown
2020-12-18  7:10         ` Greg KH
2020-12-18  7:10           ` Greg KH
2020-12-18 13:17           ` Mark Brown
2020-12-18 13:17             ` Mark Brown
2020-12-18 13:46             ` Lee Jones
2020-12-18 13:46               ` Lee Jones
2020-12-18 14:08             ` Jason Gunthorpe
2020-12-18 14:08               ` Jason Gunthorpe
2020-12-18 15:52               ` Mark Brown
2020-12-18 15:52                 ` Mark Brown
2020-12-18 16:28                 ` Jason Gunthorpe
2020-12-18 16:28                   ` Jason Gunthorpe
2020-12-18 17:15                   ` Alexandre Belloni
2020-12-18 17:15                     ` Alexandre Belloni
2020-12-18 18:03                   ` Mark Brown
2020-12-18 18:03                     ` Mark Brown
2020-12-18 18:41                     ` Jason Gunthorpe
2020-12-18 18:41                       ` Jason Gunthorpe
2020-12-18 19:09                       ` Lee Jones
2020-12-18 19:09                         ` Lee Jones
2020-12-18 20:14                         ` Jason Gunthorpe
2020-12-18 20:14                           ` Jason Gunthorpe
2020-12-18 20:32                       ` Mark Brown
2020-12-18 20:32                         ` Mark Brown
2020-12-18 20:58                         ` Jason Gunthorpe [this message]
2020-12-18 20:58                           ` Jason Gunthorpe
2020-12-18 21:16                           ` Alexandre Belloni
2020-12-18 21:16                             ` Alexandre Belloni
2020-12-18 22:36                             ` Dan Williams
2020-12-18 22:36                               ` Dan Williams
2020-12-18 23:36                             ` Jason Gunthorpe
2020-12-18 23:36                               ` Jason Gunthorpe
2020-12-19  0:22                               ` Alexandre Belloni
2020-12-19  0:22                                 ` Alexandre Belloni
2020-12-21 18:51                           ` Mark Brown
2020-12-21 18:51                             ` Mark Brown
2021-01-04 18:08                             ` Jason Gunthorpe
2021-01-04 18:08                               ` Jason Gunthorpe
2021-01-04 21:19                               ` Mark Brown
2021-01-04 21:19                                 ` Mark Brown
2021-01-05  0:13                                 ` Jason Gunthorpe
2021-01-05  0:13                                   ` Jason Gunthorpe
2021-01-05  0:51                                   ` Dan Williams
2021-01-05  0:51                                     ` Dan Williams
2021-01-05  1:53                                     ` Jason Gunthorpe
2021-01-05  1:53                                       ` Jason Gunthorpe
2021-01-05  3:12                                       ` Dan Williams
2021-01-05  3:12                                         ` Dan Williams
2021-01-05 12:49                                         ` Jason Gunthorpe
2021-01-05 12:49                                           ` Jason Gunthorpe
2021-01-05 13:42                                   ` Mark Brown
2021-01-05 13:42                                     ` Mark Brown
2021-01-05 14:36                                     ` Jason Gunthorpe
2021-01-05 14:36                                       ` Jason Gunthorpe
2021-01-05 15:47                                       ` Mark Brown
2021-01-05 15:47                                         ` Mark Brown
2020-12-04 12:35 ` Greg KH
2020-12-04 12:35   ` Greg KH
2020-12-04 12:54   ` Leon Romanovsky
2020-12-04 12:54     ` Leon Romanovsky
2020-12-04 16:25     ` Jakub Kicinski
2020-12-04 16:25       ` Jakub Kicinski
2020-12-04 17:57       ` Saeed Mahameed
2020-12-04 17:57         ` Saeed Mahameed
2020-12-04 18:05   ` Ranjani Sridharan
2020-12-04 18:05     ` Ranjani Sridharan
2020-12-06  0:24 ` David Ahern
2020-12-06  0:24   ` David Ahern
2020-12-06  0:32   ` Dan Williams
2020-12-06  0:32     ` Dan Williams

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