From: swarren@wwwdotorg•org (Stephen Warren)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH RFC v2 3/5] spmi: add generic SPMI controller binding documentation
Date: Wed, 28 Aug 2013 12:32:54 -0600 [thread overview]
Message-ID: <521E4256.4070805@wwwdotorg.org> (raw)
In-Reply-To: <20130828180025.GA808@joshc.qualcomm.com>
On 08/28/2013 12:00 PM, Josh Cartwright wrote:
> On Tue, Aug 27, 2013 at 03:55:19PM -0600, Stephen Warren wrote:
>> On 08/27/2013 11:01 AM, Josh Cartwright wrote:
>> ...
>>> If we want to ensure for the generic bindings that we are fulling
>>> characterizing/describing the SPMI bus, then we'll additionally need to
>>> tackle an additional identified assumption:
>>>
>>> 4. One master per SPMI bus. (The SPMI spec allows for up to 4
>>> masters)
>>>
>>> On the Snapdragon 800 series, there exists only one software-controlled
>>> master, but it is conceivably possible to have a setup with two
>>> software-controlled masters on the same SPMI bus.
>>>
>>> This necessarily means that the description of the slaves and the
>>> masters will need to be decoupled; I'm imagining a generic binding
>>> supporting multiple masters would look something like this:
>>
>> Is there a need to represent the other masters in the DT? Sure they're
>> there in HW, but if there's no specific way for the
>> CPU-to-which-the-DT-applies to actually interact with those other
>> masters (except perhaps by experiencing some arbitration delays) then
>> presumably there's no need to represent the other masters in DT?
>
> My example is contrived, but there is nothing in the SPMI spec
> preventing two masters from being controllable by the same
> CPU-to-which-the-DT-applies, sharing the same underlying bus.
That's true.
> I would also expect this configuration to be uncommon, I'm checking with
> some folks with more SPMI experience to make sure they agree.
>
> Interestingly, i2c as far as I can tell has also made the same
> assumption. There doesn't appear to be any way to express a
> multi-master i2c setup where both masters are controlled by the same OS.
Yes, I think it's a fair assumption that we don't need to represent
that; I immediately thought about the I2C counter-example after reading
your first paragraph.
next prev parent reply other threads:[~2013-08-28 18:32 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-22 20:18 [PATCH RFC v2 0/3] Add support for the System Power Management Interface (SPMI) Josh Cartwright
2013-08-09 20:37 ` [PATCH RFC v2 4/5] spmi: Add MSM PMIC Arbiter SPMI controller Josh Cartwright
2013-08-09 20:37 ` [PATCH RFC v2 5/5] spmi: document the PMIC arbiter SPMI bindings Josh Cartwright
2013-08-23 21:55 ` Stephen Warren
2013-08-09 20:37 ` [PATCH RFC v2 2/5] spmi: Linux driver framework for SPMI Josh Cartwright
2013-08-22 23:10 ` Greg Kroah-Hartman
2013-08-23 16:06 ` Josh Cartwright
2013-09-09 15:52 ` Mark Brown
2013-09-09 16:56 ` Josh Cartwright
2013-08-22 19:59 ` [PATCH RFC v2 3/5] spmi: add generic SPMI controller binding documentation Josh Cartwright
2013-08-23 21:58 ` Stephen Warren
2013-08-27 17:01 ` Josh Cartwright
2013-08-27 21:55 ` Stephen Warren
2013-08-28 18:00 ` Josh Cartwright
2013-08-28 18:32 ` Stephen Warren [this message]
2013-10-06 6:11 ` Bjorn Andersson
2013-10-07 21:17 ` Josh Cartwright
2013-08-22 22:57 ` [PATCH RFC v2 1/5] of: Add empty for_each_available_child_of_node() macro definition Josh Cartwright
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=521E4256.4070805@wwwdotorg.org \
--to=swarren@wwwdotorg$(echo .)org \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox