From: thierry.reding@gmail•com (Thierry Reding)
To: linux-arm-kernel@lists•infradead.org
Subject: [Ksummit-2013-discuss] ARM topic: Is DT on ARM the solution, or is there something better?
Date: Tue, 22 Oct 2013 11:45:16 +0200 [thread overview]
Message-ID: <20131022094515.GD15640@ulmo.nvidia.com> (raw)
In-Reply-To: <52658918.1060708@wwwdotorg.org>
On Mon, Oct 21, 2013 at 09:05:44PM +0100, Stephen Warren wrote:
> On 10/21/2013 12:44 AM, Guenter Roeck wrote:
> > On 10/20/2013 04:11 PM, Russell King - ARM Linux wrote:
> >> On Sun, Oct 20, 2013 at 10:26:54PM +0100, Stephen Warren wrote:
> >>> The only thing we've really moved out of the kernel is the exact IDs of
> >>> which GPIOS, interrupts, I2C/SPI ports the devices are connected to; the
> >>> simple stuff not the hard stuff. The code hasn't really been simplified
> >>> by DT - if anything, it's more complicated since we now have to parse
> >>> those values from DT rather than putting them into simple
> >>> data-structures.
> >>
> >> Here's my random thoughts this evening on DT, orientated mostly on a
> >> problem area I've been paying attention to recently.
> >>
> >> In some ways, DT has made things much harder. I don't know whether
> >
> > On the other side, DT has made some things much simpler.
> >
> > Problem case: Chip A's interrupt pin is connected to gpio pin of chip B.
> > Chip B's interrupt pin is connected to a gpio pin on chip C. Chip C's
> > interrupt pin is connected to the interrupt controller. Chips B and C
> > are multi-function FPGAs. Exact gpio pins used vary from board to board.
> >
> > With DT, this relationship is easy to describe, and none of the chip
> > drivers
> > really needs to know what is connected to what. Without DT, it would be
> > much more complex.
>
> I thought that was very easy with board files. For every chip that gets
> instantiated, you tell it which base IRQ ID to use. For every chip that
> outputs a IRQ, you tell it which IRQ ID that signal is, simply by adding
> the recipient chip's IRQ base and an offset. That seems very simple. If
> you don't want to add the base/offset together, we could always have
> invented some lookup table similar to what regulators had, and pinctrl
> has now, which says for each (device name, IRQ name/number) output,
> here's the (device name, IRQ name/number) of the associated input.
Well, DT has certainly increased the level of dynamicity within the
kernel. I for one consider not having to rely on a fixed IRQ or GPIO
base per-chip a good thing. Deferred probing is a very powerful yet
extremely simple tool that was created as part of the DT conversion
effort. There is obviously much more that can be done, but I think
that we have come a long way.
But as you said, that could all have been done even with board files.
Thierry
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next prev parent reply other threads:[~2013-10-22 9:45 UTC|newest]
Thread overview: 171+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-20 21:26 ARM topic: Is DT on ARM the solution, or is there something better? Stephen Warren
2013-10-20 22:08 ` [Ksummit-2013-discuss] " Mark Brown
2013-10-20 22:21 ` Stephen Warren
2013-10-21 1:00 ` Nicolas Pitre
2013-10-21 9:15 ` Thierry Reding
2013-10-21 14:57 ` Maxime Bizon
2013-10-21 17:07 ` Richard Cochran
2013-10-21 20:24 ` Stephen Warren
2013-10-22 9:24 ` Thierry Reding
2013-10-23 17:30 ` Richard Cochran
2013-10-23 19:06 ` Thierry Reding
2013-10-22 17:22 ` Jason Gunthorpe
2013-10-21 20:29 ` Stephen Warren
2013-10-21 20:40 ` Nicolas Pitre
2013-10-22 9:39 ` Thierry Reding
2013-10-22 15:04 ` Matt Porter
2013-10-22 17:13 ` Jason Gunthorpe
2013-10-22 17:49 ` Guenter Roeck
2013-10-23 8:06 ` Richard Cochran
2013-10-23 9:49 ` Thierry Reding
2013-10-23 17:16 ` Richard Cochran
2013-10-23 17:25 ` Matt Porter
2013-10-23 18:05 ` Richard Cochran
2013-10-23 18:57 ` Nicolas Pitre
2013-10-23 20:12 ` Matt Porter
2013-10-23 17:55 ` Nicolas Pitre
2013-10-23 18:13 ` Richard Cochran
2013-10-23 20:35 ` Thierry Reding
2013-10-23 17:29 ` Jason Gunthorpe
2013-10-23 17:45 ` Richard Cochran
2013-10-23 18:46 ` Maxime Bizon
2013-10-23 18:51 ` Richard Cochran
2013-10-23 19:12 ` Maxime Bizon
2013-10-24 9:52 ` Grant Likely
2013-10-24 11:33 ` Maxime Bizon
2013-10-24 11:47 ` David Woodhouse
2013-10-24 12:13 ` Maxime Bizon
2013-10-24 12:22 ` David Woodhouse
2013-10-24 12:22 ` David Woodhouse
2013-10-24 13:05 ` Maxime Bizon
2013-10-24 13:14 ` David Woodhouse
2013-10-24 13:46 ` Maxime Bizon
2013-10-24 19:52 ` Matt Porter
2013-10-24 20:11 ` Matt Sealey
2013-10-25 9:00 ` Stephen Warren
2013-10-24 12:23 ` Thierry Reding
2013-10-24 12:29 ` David Woodhouse
2013-10-24 13:00 ` Maxime Bizon
2013-10-24 13:10 ` David Woodhouse
2013-10-24 13:30 ` Maxime Bizon
2013-10-24 14:05 ` David Woodhouse
2013-10-24 14:19 ` Thierry Reding
2013-10-24 14:30 ` David Woodhouse
2013-10-24 14:38 ` Thierry Reding
2013-10-24 16:39 ` Nicolas Pitre
2013-10-24 16:45 ` David Woodhouse
2013-10-24 17:08 ` Nicolas Pitre
2013-10-24 18:15 ` jonsmirl at gmail.com
2013-10-24 14:32 ` Richard Cochran
2013-10-24 14:47 ` Thierry Reding
2013-10-24 15:37 ` Nicolas Pitre
2013-10-24 14:33 ` Maxime Bizon
2013-10-24 14:57 ` Thierry Reding
2013-10-24 16:27 ` Nicolas Pitre
2013-10-24 14:12 ` Thierry Reding
2013-10-24 14:22 ` David Woodhouse
2013-10-24 14:23 ` Thierry Reding
2013-10-24 14:38 ` David Woodhouse
2013-10-24 14:58 ` Thierry Reding
2013-10-24 19:58 ` Matt Porter
2013-10-24 23:54 ` Grant Likely
2013-10-25 8:52 ` Stephen Warren
2013-10-25 9:16 ` Thierry Reding
2013-10-23 17:47 ` Richard Cochran
2013-10-23 17:58 ` Nicolas Pitre
2013-10-23 18:02 ` Jason Gunthorpe
2013-10-23 18:23 ` Richard Cochran
2013-10-24 8:34 ` Thierry Reding
2013-10-24 15:00 ` Richard Cochran
2013-10-24 19:46 ` Matt Porter
2013-10-23 18:01 ` Guenter Roeck
2013-10-23 18:25 ` Jason Gunthorpe
2013-10-23 18:30 ` Richard Cochran
2013-10-23 18:54 ` Jason Gunthorpe
2013-10-24 8:06 ` Sascha Hauer
2013-10-24 8:17 ` Thierry Reding
2013-10-24 8:52 ` Sascha Hauer
2013-10-23 23:29 ` Ben Hutchings
2013-10-24 7:32 ` Richard Cochran
2013-10-24 9:35 ` Ben Hutchings
2013-10-24 12:02 ` Andre Heider
2013-10-24 8:01 ` Sascha Hauer
2013-10-24 8:11 ` Thierry Reding
2013-10-22 17:42 ` Nicolas Pitre
2013-10-22 18:21 ` Peter Maydell
2013-10-22 18:36 ` Nicolas Pitre
2013-10-22 19:16 ` Guenter Roeck
2013-10-22 20:12 ` Thierry Reding
2013-10-22 20:41 ` Nicolas Pitre
2013-10-22 21:39 ` Jason Gunthorpe
2013-10-23 8:50 ` Thierry Reding
2013-10-23 9:02 ` Thierry Reding
2013-10-22 20:42 ` Matt Porter
2013-10-23 10:04 ` Thierry Reding
2013-10-23 11:48 ` Peter Maydell
2013-10-23 16:29 ` Matt Porter
2013-10-22 6:47 ` David Brown
2013-10-20 23:11 ` Russell King - ARM Linux
2013-10-20 23:44 ` [Ksummit-2013-discuss] " Guenter Roeck
2013-10-20 23:51 ` Russell King - ARM Linux
2013-10-21 0:13 ` Guenter Roeck
2013-10-21 20:05 ` Stephen Warren
2013-10-22 9:45 ` Thierry Reding [this message]
2013-10-21 8:32 ` Sascha Hauer
2013-10-21 8:48 ` Russell King - ARM Linux
2013-10-21 9:27 ` Sascha Hauer
[not found] ` < CAF6AEGtt_2sStiZCNBp9btxevWghSwLZZBdN6ir8eUpX1FXrCQ@mail.gmail.com>
[not found] ` < 20131024072811.GS30088@pengutronix.de>
[not found] ` < CAF6AEGuEho9Ms7ifTE-EmBoQ-=_AXgvGcJxi5qEC0vsZ+H9C+A@mail.gmail.com>
2013-10-21 9:57 ` Russell King - ARM Linux
2013-10-21 10:24 ` Thierry Reding
2013-10-21 10:30 ` Russell King - ARM Linux
2013-10-21 10:41 ` Thierry Reding
2013-10-22 9:19 ` [Ksummit-2013-discuss] " Mark Brown
2013-10-21 20:09 ` Stephen Warren
2013-10-21 23:18 ` Sascha Hauer
2013-10-24 1:14 ` Rob Clark
2013-10-24 7:28 ` Sascha Hauer
2013-10-24 9:00 ` Thierry Reding
2013-10-24 9:21 ` Sascha Hauer
2013-10-24 21:21 ` Rob Clark
2013-10-25 9:24 ` Thierry Reding
2013-11-18 12:45 ` Russell King - ARM Linux
2013-11-18 15:37 ` Thierry Reding
2013-11-18 16:11 ` Russell King - ARM Linux
2013-11-18 16:18 ` Thierry Reding
2013-11-18 18:43 ` Mark Brown
2013-11-19 13:54 ` Grant Likely
2013-10-21 10:04 ` Thierry Reding
2013-10-21 10:57 ` [Ksummit-2013-discuss] " Laurent Pinchart
2013-10-21 10:00 ` Laurent Pinchart
2013-10-21 11:18 ` Sebastian Hesselbarth
2013-10-21 8:54 ` Thierry Reding
2013-10-21 20:19 ` Stephen Warren
2013-10-21 22:51 ` [Ksummit-2013-discuss] " Guenter Roeck
2013-10-22 10:27 ` James Hogan
2013-10-22 16:31 ` Jonathan Cameron
2013-10-22 16:49 ` Guenter Roeck
2013-10-22 20:35 ` Thierry Reding
2013-10-22 21:10 ` Guenter Roeck
2013-10-23 7:57 ` Thierry Reding
2013-10-23 16:01 ` Guenter Roeck
2013-10-23 21:07 ` Thierry Reding
2013-10-24 15:18 ` Guenter Roeck
2013-11-01 10:36 ` Thierry Reding
2013-11-01 13:30 ` Guenter Roeck
2013-10-22 20:48 ` Thierry Reding
2013-10-22 10:25 ` Thierry Reding
2013-10-22 21:44 ` Matt Sealey
2013-10-23 11:41 ` Peter Maydell
2013-10-23 23:02 ` [Ksummit-2013-discuss] " Rob Herring
2013-11-18 12:26 ` Thierry Reding
2013-11-18 13:40 ` Grant Likely
2013-11-18 13:57 ` Mark Brown
2013-11-18 15:29 ` Thierry Reding
2013-11-18 15:50 ` Mark Brown
2013-11-18 16:06 ` Thierry Reding
2013-11-18 17:16 ` Stephen Warren
2013-11-19 9:35 ` Thierry Reding
2013-11-19 17:27 ` Stephen Warren
2013-11-20 13:29 ` Thierry Reding
2013-11-18 18:35 ` Mark Brown
2013-11-19 9:11 ` Thierry Reding
2013-11-19 10:16 ` Mark Brown
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