From: Laxman Dewangan <ldewangan-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
To: Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Bjorn Andersson
<bjorn.andersson-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Cc: robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
pawel.moll-5wv7dgnIgG8@public.gmane.org,
mark.rutland-5wv7dgnIgG8@public.gmane.org,
ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org,
lgirdwood-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org,
bjorn.andersson-/MT0OVThwyLZJqsBc5GL+g@public.gmane.org,
swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org,
devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH 1/2] regulator: DT: Add support to scale ramp delay based on platform behavior
Date: Tue, 1 Mar 2016 09:18:46 +0530 [thread overview]
Message-ID: <56D5111E.6090606@nvidia.com> (raw)
In-Reply-To: <20160301022326.GC18327-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
On Tuesday 01 March 2016 07:53 AM, Mark Brown wrote:
> * PGP Signed by an unknown key
>
> On Mon, Feb 29, 2016 at 09:47:51AM -0800, Bjorn Andersson wrote:
>> On Mon 29 Feb 06:40 PST 2016, Laxman Dewangan wrote:
>>> It is observed that voltage change in given rail affected by the load
>>> and the capacitor in the rail. This may cause the slow ramp in voltage
>>> against what PMIC has programmed.
>> The regulator-ramp-delay is a variable you can tweak on a board basis,
>> so I'm not sure what benefit it gives to be able to add a scaling
>> factor to this.
>> In my experience your HW engineer will say "you have to wait X ms", not
>> "you have to wait 125% of X ms".
>> Can you please elaborate on why the original knob isn't sufficient?
> Right, this definitely feels like the wrong thing is being specified
> here (and also like the PMIC might be going out of spec, possibly as a
> result of being overloaded) and that the existing board specific
> controls should be used. It just doesn't correspond to the way people
> usually talk about specs for PMICs.
>
Most of PMICs offer to configure the slew rate (ramp time). For
discussion, I am considering MAX77620 LDOs provides option to 27mV/us
and 100mV/us.
HW team characterize the board and its rail and come up with the
following data:
- Configure PMIC to 27mV/us for ramp time.
- With this measured value of ramp on board is 10mV/us and it is safe
to assume 5mv/us to consider the board variations.
So we have now two input from HW team:
1. What should be configure in PMIC.
2. And for calculation, how much ramp need to be consider.
For (1), it is 25mV/us and for (2) which 540% (27 *100/5).
Currently, we can provide the 27mv/us as ramp-delay but do not have
option for scaling it.
My patch add for knob for (2).
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2016-03-01 3:48 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 [this message]
[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
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=56D5111E.6090606@nvidia.com \
--to=ldewangan-ddmlm1+adcrqt0dzr+alfa@public.gmane.org \
--cc=bjorn.andersson-/MT0OVThwyLZJqsBc5GL+g@public.gmane.org \
--cc=bjorn.andersson-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org \
--cc=broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org \
--cc=devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org \
--cc=lgirdwood-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org \
--cc=linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=mark.rutland-5wv7dgnIgG8@public.gmane.org \
--cc=pawel.moll-5wv7dgnIgG8@public.gmane.org \
--cc=robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org \
--cc=swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org \
/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).