linux-kernel - Re: [PATCH part2 5/6] regulator: max14577: Implement SUSPEND mode for MAX77836 LDO-s

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 05 May 2014 10:47:24 +0200
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Mark Brown <broonie@...nel.org>
Cc:	Samuel Ortiz <sameo@...ux.intel.com>,
	Lee Jones <lee.jones@...aro.org>,
	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	David Woodhouse <dwmw2@...radead.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	linux-kernel@...r.kernel.org,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Tomasz Figa <t.figa@...sung.com>,
	Anton Vorontsov <anton@...msg.org>
Subject: Re: [PATCH part2 5/6] regulator: max14577: Implement SUSPEND mode for
 MAX77836 LDO-s

On czw, 2014-05-01 at 11:19 -0700, Mark Brown wrote:
> On Wed, Apr 23, 2014 at 04:50:39PM +0200, Krzysztof Kozlowski wrote:
> 
> > This patch adds support for mode REGULATOR_MODE_STANDBY (and NORMAL) to
> > LDO regulators by implementing the set_mode() and get_mode() operations.
> > However the necessary regulator constraints (valid modes) are not parsed
> > by of_regulator_match() so the driver adds them manually to the
> > regulator init_data.
> 
> No, that's not the idea here.  The reason that the modes need to be
> explicitly enabled is that there's an element of board design in
> determining if a given mode can satisfy the required current demand for
> the board with sufficient quality (usually the lower power modes have
> both a lower maximum current and poorer regulation accuracy especially
> as the current rises).  Doing it unconditionally isn't in general
> reliable.
> 
> The reason that the modes aren't supported by DT is that defining a
> binding is hard - it's not clear what exactly a "mode" means since it's
> basically a Linux internal thing.  We probably need to explicitly add
> definitions of the modes to the bindings for individual devices
> unfortunately (ie, saying "mode X maps to Y in the datasheet", possibly
> using the datasheet modes in the binding for ease of use and having that
> translation in the driver).
> 
> Ideally we'd be able to have the automatic mode setting working for
> devices but in practice nobody wants to publish the numbers and working
> out how much the board needs can also be hard so that isn't really
> practical.

I understand. Lets skip this patch now. I will prepare in the future a
version of this patch with own DT binding for max77836 suspend mode.

Best regards,
Krzysztof

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/