From: Laxman Dewangan <ldewangan@nvidia.com>
To: Bjorn Andersson <bjorn@kryo.se>
Cc: Mark Brown <broonie@kernel.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Ian Campbell <ijc+devicetree@hellion.org.uk>,
Liam Girdwood <lgirdwood@gmail.com>,
Bjorn Andersson <bjorn.andersson@sonymobile.com>,
Stephen Warren <swarren@wwwdotorg.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Gandhar Dighe <gdighe@nvidia.com>,
Stuart Yates <syates@nvidia.com>
Subject: Re: [PATCH 1/2] regulator: DT: Add support to scale ramp delay based on platform behavior
Date: Sat, 19 Mar 2016 14:05:36 +0530 [thread overview]
Message-ID: <56ED0F58.7060005@nvidia.com> (raw)
In-Reply-To: <CAJAp7OgUjN+Ymh+vM8g9Wex0JDRSOFkvpTKHm8fXYkDgTQ+0Tw@mail.gmail.com>
On Saturday 19 March 2016 10:01 AM, Bjorn Andersson wrote:
> On Tue, Mar 15, 2016 at 6:41 AM, Laxman Dewangan <ldewangan@nvidia.com> wrote:
>> On Wednesday 02 March 2016 10:05 AM, Mark Brown wrote:
>>> * PGP Signed by an unknown key
>>>
>>> On Wed, Mar 02, 2016 at 09:05:26AM +0530, Laxman Dewangan wrote:
>>>> On Wednesday 02 March 2016 09:08 AM, Mark Brown wrote:
>>>>> You're not trying to scale the value here, you're trying to replace the
>>>>> value because the PMIC is incapable of delivering the advertised ramp
>>>>> rate. Trying to express this as a multiple of the advertised ramp rate
>>>>> is just adding complexity.
>>>> So should we provide absolute ramp value here for platform specific?
>>> Yes, otherwise if the PMIC vendor respecifies their ramp rates to
>>> reflect reality and the driver is updated then your DT will be broken.
>>>
>>>> Or any other suggestion to handle this situation as this is very common
>>>> and
>>>> almost all our boards have this slowness on ramp.
>>> Perhaps time to have a chat with your PMIC vendors...
>>>
>> I had discussion with our HW team to get more information about this
>> variation.
>> They said that Maxim advertise the ramp time with given condition in
>> interface i.e. capacitance etc which is very generic.
>> We did the experiment with Maxim recommendation about the rail and its
>> capacitance (2.2uF) and found that measured value is same as what they
>> advertise in datasheet.
>>
>> When chip team use this PMIC with Tegra hardware specs and did the circuit
>> simulation to ensures how our boards should be designed for signal integrity
>> they suggested that the rail capacitance should be more than what Maxim
>> recommending in general to work with our silicon. So here condition get
>> changed and hence the effective ramp time.
>>
>> So here we will need two parameters:
>> advertised-ramp-delay for PMIC configurations and
>> ramp-delay which is measured one.
>>
>> Most of time, advertised-ramp-delay is same as ramp-delay and hence one
>> value from DT will be sufficient.
>> If there is difference then both value can be provided and
>> advertised-ramp-delay will be used for PMIC configuration and rest of
>> calculation about delay will be from ramp-delay.
>>
> Generally the device driver should describe the PMIC and the device
> tree should describe the board. So the Maxim's numbers should (if
> specified at all) go into the driver and the measures/calculated
> characteristics for your board should be specified in the dt.
>
> The ramp properties in the generic regulator binding is used to inform
> the OS about the board's ramp properties.
>
>
> If I understand you correctly the Maxim PMIC can be configured to
> drive the change at different speed, this should be configured through
> a Maxim specific property. It should not reuse the generic properties
> for ramp delays.
>
Ramp delay configurations are seen on other vendor's PMIC devices also.
Therefore, I like o me generic property rather than specific to Maxim.
Parsing can be done in the core framework and applied during setting
machine constraints.
next prev parent reply other threads:[~2016-03-19 8:35 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-29 14:40 [PATCH 1/2] regulator: DT: Add support to scale ramp delay based on platform behavior Laxman Dewangan
[not found] ` <1456756829-2277-1-git-send-email-ldewangan-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2016-02-29 14:40 ` [PATCH 2/2] regulator: " Laxman Dewangan
2016-02-29 17:47 ` [PATCH 1/2] regulator: DT: " Bjorn Andersson
2016-03-01 2:23 ` Mark Brown
[not found] ` <20160301022326.GC18327-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2016-03-01 3:48 ` Laxman Dewangan
[not found] ` <56D5111E.6090606-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2016-03-02 3:38 ` Mark Brown
2016-03-02 3:35 ` Laxman Dewangan
[not found] ` <56D65F7E.3090907-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2016-03-02 4:35 ` Mark Brown
2016-03-02 6:12 ` Laxman Dewangan
2016-03-15 13:41 ` Laxman Dewangan
[not found] ` <56E81103.8010903-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2016-03-15 14:48 ` Mark Brown
2016-03-16 11:30 ` Laxman Dewangan
2016-03-19 4:31 ` Bjorn Andersson
2016-03-19 8:35 ` Laxman Dewangan [this message]
2016-03-30 13:29 ` Laxman Dewangan
2016-03-30 18:16 ` Mark Brown
2016-03-31 7:06 ` Laxman Dewangan
2016-03-31 16:51 ` Mark Brown
[not found] ` <20160331165145.GF2350-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2016-03-31 17:13 ` Laxman Dewangan
[not found] ` <56FD5A9F.5050001-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2016-03-31 17:47 ` Mark Brown
[not found] ` <20160331174741.GO2350-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2016-03-31 17:47 ` Laxman Dewangan
2016-03-31 18:31 ` Mark Brown
[not found] ` <20160331183130.GR2350-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2016-03-31 18:31 ` Laxman Dewangan
2016-03-31 18:45 ` Mark Brown
[not found] ` <20160331184553.GS2350-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2016-03-31 18:39 ` Laxman Dewangan
2016-03-31 18:59 ` Mark Brown
[not found] ` <20160331185945.GT2350-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2016-03-31 18:59 ` Laxman Dewangan
2016-03-31 19:22 ` Mark Brown
2016-03-31 19:48 ` Laxman Dewangan
[not found] ` <56FD7F07.7010404-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2016-03-31 20:39 ` Mark Brown
[not found] ` <20160331203942.GV2350-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2016-04-01 7:15 ` Laxman Dewangan
2016-04-01 16:11 ` Mark Brown
[not found] ` <20160401161121.GZ2350-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2016-04-05 8:01 ` Laxman Dewangan
[not found] ` <570370E5.3070901-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2016-04-12 1:02 ` Mark Brown
2016-04-12 13:29 ` Laxman Dewangan
[not found] ` <570CF822.4050002-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2016-04-13 6:53 ` Mark Brown
2016-04-19 10:01 ` Laxman Dewangan
2016-04-19 10:55 ` Mark Brown
[not found] ` <20160419105545.GT3217-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2016-04-19 10:56 ` Laxman Dewangan
2016-04-19 15:47 ` Mark Brown
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=56ED0F58.7060005@nvidia.com \
--to=ldewangan@nvidia.com \
--cc=bjorn.andersson@linaro.org \
--cc=bjorn.andersson@sonymobile.com \
--cc=bjorn@kryo.se \
--cc=broonie@kernel.org \
--cc=devicetree@vger.kernel.org \
--cc=gdighe@nvidia.com \
--cc=ijc+devicetree@hellion.org.uk \
--cc=lgirdwood@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=pawel.moll@arm.com \
--cc=robh+dt@kernel.org \
--cc=swarren@wwwdotorg.org \
--cc=syates@nvidia.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).