From: David Daney <ddaney.cavm@gmail.com>
To: Grant Likely <grant.likely@secretlab.ca>
Cc: Alan Stern <stern@rowland.harvard.edu>,
Ming Lei <tom.leiming@gmail.com>,
Andrei Warkentin <awarkentin@vmware.com>,
Greg KH <greg@kroah.com>, Dilan Lee <dilee@nvidia.com>,
"G, Manjunath Kondaiah" <manjugk@ti.com>,
Mark Brown <broonie@opensource.wolfsonmicro.com>,
linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org,
Josh Triplett <josh@joshtriplett.org>,
Manjunath@jasper.es, linux-omap@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Linux PM List <linux-pm@vger.kernel.org>,
"Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: [PATCH 2/5] drivercore: Add driver probe deferral mechanism
Date: Fri, 14 Oct 2011 11:56:15 -0700 [thread overview]
Message-ID: <4E9885CF.1000301@gmail.com> (raw)
In-Reply-To: <CACxGe6t2Xu5B0AKZJe-6HEpxK6GfuNm0Y2Kb_bs8ZwaTz5XnRg@mail.gmail.com>
On 10/14/2011 10:20 AM, Grant Likely wrote:
> On Fri, Oct 14, 2011 at 10:33 AM, Alan Stern<stern@rowland.harvard.edu> wrote:
>> On Fri, 14 Oct 2011, Grant Likely wrote:
>>
>>>> How can a device acquire children before it has a driver?
>>>
>>> There are a few potential situations in embedded systems (or at least
>>> nothing currently prevents it) where platform setup code constructs a
>>> device hierarchy without the aid of device drivers, and it is still
>>> possible for a parent device to be attached to a driver. IIUC, SPARC
>>> creates an entire hierarchy of platform_devices from all the nodes in
>>> the OpenFirmware device tree, and any of those devices can be bound to
>>> a driver. I don't like that approach, but at the very least it needs
>>> to be guarded against.
>>
>> Do these devices ever require deferred probes?
>
> Yes, they very well might. However, I'm happy with the limitation
> that only leaf devices can take advantage of probe deferral.
>
I have:
I2C-Bus-A
+--Mux-I2C (controlled by parent I2C-Bus-A)
+---I2C-Bus-1
| +--GPIO-Expander-A
|
+---I2C-Bus-2
+--GPIO-Expander-B
These all have a parent/child relationship so no deferral is needed, so
far so good.
Then this:
MDIO-Bus-A
+---Mux-MDIO (controlled by GPIO-Expander-A)
+---MDIO-Bus-1
|
+---MDIO-Bus-2
+---PHY-1
|
+---PHY-2
In this case the driver for Mux-MDIO needs to be deferred until *both*
MDIO-Bus-A's driver *and* GPIO-Expander-B's driver are loaded. A
perfect use case for the patch.
Would you consider Mux-MDIO to be a 'leaf device'? If not, then I have
real problems with 'the limitation that only leaf devices can take
advantage of probe deferral'
David Daney
WARNING: multiple messages have this Message-ID (diff)
From: ddaney.cavm@gmail.com (David Daney)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/5] drivercore: Add driver probe deferral mechanism
Date: Fri, 14 Oct 2011 11:56:15 -0700 [thread overview]
Message-ID: <4E9885CF.1000301@gmail.com> (raw)
In-Reply-To: <CACxGe6t2Xu5B0AKZJe-6HEpxK6GfuNm0Y2Kb_bs8ZwaTz5XnRg@mail.gmail.com>
On 10/14/2011 10:20 AM, Grant Likely wrote:
> On Fri, Oct 14, 2011 at 10:33 AM, Alan Stern<stern@rowland.harvard.edu> wrote:
>> On Fri, 14 Oct 2011, Grant Likely wrote:
>>
>>>> How can a device acquire children before it has a driver?
>>>
>>> There are a few potential situations in embedded systems (or at least
>>> nothing currently prevents it) where platform setup code constructs a
>>> device hierarchy without the aid of device drivers, and it is still
>>> possible for a parent device to be attached to a driver. IIUC, SPARC
>>> creates an entire hierarchy of platform_devices from all the nodes in
>>> the OpenFirmware device tree, and any of those devices can be bound to
>>> a driver. I don't like that approach, but at the very least it needs
>>> to be guarded against.
>>
>> Do these devices ever require deferred probes?
>
> Yes, they very well might. However, I'm happy with the limitation
> that only leaf devices can take advantage of probe deferral.
>
I have:
I2C-Bus-A
+--Mux-I2C (controlled by parent I2C-Bus-A)
+---I2C-Bus-1
| +--GPIO-Expander-A
|
+---I2C-Bus-2
+--GPIO-Expander-B
These all have a parent/child relationship so no deferral is needed, so
far so good.
Then this:
MDIO-Bus-A
+---Mux-MDIO (controlled by GPIO-Expander-A)
+---MDIO-Bus-1
|
+---MDIO-Bus-2
+---PHY-1
|
+---PHY-2
In this case the driver for Mux-MDIO needs to be deferred until *both*
MDIO-Bus-A's driver *and* GPIO-Expander-B's driver are loaded. A
perfect use case for the patch.
Would you consider Mux-MDIO to be a 'leaf device'? If not, then I have
real problems with 'the limitation that only leaf devices can take
advantage of probe deferral'
David Daney
next prev parent reply other threads:[~2011-10-14 18:56 UTC|newest]
Thread overview: 116+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-07 5:33 [PATCH 0/5] Driver Probe Deferral Mechanism G, Manjunath Kondaiah
2011-10-07 5:33 ` [PATCH 1/5] drivercore: add new error value for deferred probe G, Manjunath Kondaiah
2011-10-07 6:43 ` Greg KH
2011-10-07 6:43 ` Greg KH
2011-10-07 10:00 ` Mark Brown
2011-10-07 10:00 ` Mark Brown
2011-10-07 22:12 ` Grant Likely
2011-10-07 22:12 ` Grant Likely
2011-10-07 23:28 ` Valdis.Kletnieks
2011-10-07 23:28 ` Valdis.Kletnieks
2011-10-07 23:28 ` Valdis.Kletnieks at vt.edu
2011-10-08 0:12 ` Greg KH
2011-10-08 0:12 ` Greg KH
2011-10-09 22:59 ` Grant Likely
2011-10-09 22:59 ` Grant Likely
2011-10-09 22:59 ` Grant Likely
2011-10-10 1:06 ` Greg KH
2011-10-10 1:06 ` Greg KH
2011-10-10 1:06 ` Greg KH
2011-10-12 6:18 ` G, Manjunath Kondaiah
2011-10-12 6:18 ` G, Manjunath Kondaiah
2011-10-13 4:10 ` Grant Likely
2011-10-13 4:10 ` Grant Likely
2011-10-07 5:33 ` [PATCH 2/5] drivercore: Add driver probe deferral mechanism G, Manjunath Kondaiah
2011-10-07 6:49 ` Greg KH
2011-10-07 6:49 ` Greg KH
2011-10-07 20:57 ` Josh Triplett
2011-10-07 20:57 ` Josh Triplett
2011-10-07 21:23 ` Greg KH
2011-10-07 21:23 ` Greg KH
2011-10-08 4:03 ` Josh Triplett
2011-10-08 4:03 ` Josh Triplett
2011-10-08 15:55 ` Greg KH
2011-10-08 15:55 ` Greg KH
2011-10-08 18:18 ` Josh Triplett
2011-10-08 18:18 ` Josh Triplett
2011-10-10 17:37 ` Andrei Warkentin
2011-10-10 17:37 ` Andrei Warkentin
2011-10-11 12:29 ` Ming Lei
2011-10-11 12:29 ` Ming Lei
2011-10-13 4:09 ` Grant Likely
2011-10-13 4:09 ` Grant Likely
2011-10-13 14:18 ` Ming Lei
2011-10-13 14:18 ` Ming Lei
2011-10-13 14:31 ` Alan Stern
2011-10-13 14:31 ` Alan Stern
2011-10-13 14:31 ` Alan Stern
2011-10-13 15:21 ` Ming Lei
2011-10-13 15:21 ` Ming Lei
2011-10-13 16:04 ` Alan Stern
2011-10-13 16:04 ` Alan Stern
2011-10-13 16:04 ` Alan Stern
2011-10-14 0:13 ` Ming Lei
2011-10-14 0:13 ` Ming Lei
2011-10-13 17:15 ` Grant Likely
2011-10-13 17:15 ` Grant Likely
2011-10-13 18:16 ` Alan Stern
2011-10-13 18:16 ` Alan Stern
2011-10-13 18:16 ` Alan Stern
2011-10-13 18:28 ` Grant Likely
2011-10-13 18:28 ` Grant Likely
2011-10-14 15:39 ` Alan Stern
2011-10-14 15:39 ` Alan Stern
2011-10-14 15:39 ` Alan Stern
2011-10-14 16:17 ` Grant Likely
2011-10-14 16:17 ` Grant Likely
2011-10-14 16:33 ` Alan Stern
2011-10-14 16:33 ` Alan Stern
2011-10-14 16:33 ` Alan Stern
2011-10-14 17:20 ` Grant Likely
2011-10-14 17:20 ` Grant Likely
2011-10-14 17:33 ` Alan Stern
2011-10-14 17:33 ` Alan Stern
2011-10-14 17:33 ` Alan Stern
2011-10-14 18:25 ` Grant Likely
2011-10-14 18:25 ` Grant Likely
2011-10-14 18:39 ` Alan Stern
2011-10-14 18:39 ` Alan Stern
2011-10-14 18:39 ` Alan Stern
2011-10-14 19:07 ` Grant Likely
2011-10-14 19:07 ` Grant Likely
2011-10-14 18:56 ` David Daney [this message]
2011-10-14 18:56 ` David Daney
2011-10-14 19:03 ` Grant Likely
2011-10-14 19:03 ` Grant Likely
2011-10-14 19:03 ` Grant Likely
2011-10-14 19:09 ` David Daney
2011-10-14 19:09 ` David Daney
2011-10-14 15:37 ` Alan Stern
2011-10-14 15:37 ` Alan Stern
2011-10-14 15:37 ` Alan Stern
2011-10-12 7:04 ` G, Manjunath Kondaiah
2011-10-12 7:04 ` G, Manjunath Kondaiah
2011-10-07 21:28 ` Grant Likely
2011-10-07 21:28 ` Grant Likely
2011-10-07 21:28 ` Grant Likely
2011-10-07 5:33 ` [PATCH 3/5] regulator: Support driver probe deferral G, Manjunath Kondaiah
2011-10-07 5:33 ` [PATCH 4/5] gpiolib: handle deferral probe error G, Manjunath Kondaiah
2011-10-07 10:06 ` Alan Cox
2011-10-07 10:06 ` Alan Cox
2011-10-07 10:06 ` Alan Cox
2011-10-07 22:09 ` Grant Likely
2011-10-07 22:09 ` Grant Likely
2011-10-12 6:14 ` G, Manjunath Kondaiah
2011-10-12 6:14 ` G, Manjunath Kondaiah
2011-10-12 6:14 ` G, Manjunath Kondaiah
2011-10-13 4:12 ` Grant Likely
2011-10-13 4:12 ` Grant Likely
2011-10-07 5:33 ` [PATCH 5/5] omap: hsmmc: use platform_driver_register G, Manjunath Kondaiah
2011-10-07 6:50 ` [PATCH 0/5] Driver Probe Deferral Mechanism Greg KH
2011-10-07 6:50 ` Greg KH
2011-10-07 6:50 ` Greg KH
2011-10-07 7:37 ` G, Manjunath Kondaiah
2011-10-07 7:37 ` G, Manjunath Kondaiah
2011-10-07 7:37 ` G, Manjunath Kondaiah
-- strict thread matches above, loose matches on Subject: below --
2011-10-07 5:05 G, Manjunath Kondaiah
2011-10-07 5:05 ` [PATCH 2/5] drivercore: Add driver probe deferral mechanism G, Manjunath Kondaiah
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4E9885CF.1000301@gmail.com \
--to=ddaney.cavm@gmail.com \
--cc=Manjunath@jasper.es \
--cc=awarkentin@vmware.com \
--cc=broonie@opensource.wolfsonmicro.com \
--cc=dilee@nvidia.com \
--cc=grant.likely@secretlab.ca \
--cc=greg@kroah.com \
--cc=josh@joshtriplett.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mmc@vger.kernel.org \
--cc=linux-omap@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=manjugk@ti.com \
--cc=rjw@sisk.pl \
--cc=stern@rowland.harvard.edu \
--cc=tom.leiming@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.