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From: Viresh Kumar <viresh.kumar-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
To: Chen-Yu Tsai <wens-jdAy2FN1RRM@public.gmane.org>
Cc: Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>,
	"devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Vincent Guittot
	<vincent.guittot-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
	Greg Kroah-Hartman
	<gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>,
	Stephen Boyd <sboyd-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>,
	"linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Rajendra Nayak <rnayak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>,
	Shiraz Hashim <shashim-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>,
	"linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org"
	<linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>
Subject: Re: [RFC v2 5/6] drivers: boot_constraint: Add initial DT bindings
Date: Thu, 13 Jul 2017 10:39:34 +0530	[thread overview]
Message-ID: <20170713050934.GB352@vireshk-i7> (raw)
In-Reply-To: <CAGb2v67XtUcqdjMt-Ln6zn3ShH4JFmjkK4bPSpUNZpJqnmwivw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

On 13-07-17, 10:52, Chen-Yu Tsai wrote:
> I'm afraid the regulator case still doesn't make sense. The voltage
> constraints should be set within each supplies device node. This was
> explained in the discussion in v1 [1].

I thought we were discussing about something I mentioned in one of my example
but never to a point that the regulator problem doesn't exist at all. Perhaps I
misunderstood your concerns. Anyway, lemme try once more with a better example.

Regulator shared by: LCD and MMC (both can do DVFS) and the min/max constraint
that can be set by the consumers of the regulator (both LCD/MMC) are: 1.5 V to
3 V.

The bootloader has programmed the LCD to work at the highest pixel frequency,
which needs the voltage to be in range from 2.5 - 3 V.

Now MMC can get probed first and it can try to bring the voltages below 2.5 V.
Though, 1.5 - 2.5 is a valid range for the LCD, but not at the current pixel
frequency.

Does that sound like a valid problem?

-- 
viresh
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  parent reply	other threads:[~2017-07-13  5:09 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <cover.1499770771.git.viresh.kumar@linaro.org>
2017-07-12  6:34 ` [RFC v2 5/6] drivers: boot_constraint: Add initial DT bindings Viresh Kumar
     [not found]   ` <0610277aef9830cff53b7b53cf41cc54886fdc7f.1499770771.git.viresh.kumar-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
2017-07-12 21:28     ` Rob Herring
     [not found]       ` <CAL_Jsq+oAB3gejRMXuY0q9+Et4GrtvF3RwGzPNJ08TPooVyXJg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-07-13  2:52         ` Chen-Yu Tsai
     [not found]           ` <CAGb2v67XtUcqdjMt-Ln6zn3ShH4JFmjkK4bPSpUNZpJqnmwivw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-07-13  5:09             ` Viresh Kumar [this message]
2017-07-13  9:46               ` Chen-Yu Tsai
2017-07-13  9:51                 ` Viresh Kumar
2017-07-13  9:36       ` Viresh Kumar
2017-07-17 17:34         ` Rob Herring
2017-07-18  5:58           ` Viresh Kumar
2017-07-12  6:34 ` [RFC v2 6/6] drivers: boot_constraint: Add constraints for OF devices Viresh Kumar

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