linux-kernel - Re: [PATCH 0/4] phy: samsung-usb2: Add support for Vbus regulator

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Date:	Thu, 11 Dec 2014 18:21:45 +0530
From:	Vivek Gautam <gautamvivek1987@...il.com>
To:	David Laight <David.Laight@...lab.com>
Cc:	Vivek Gautam <gautam.vivek@...sung.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"robh+dt@...nel.org" <robh+dt@...nel.org>,
	"kishon@...com" <kishon@...com>,
	"k.debski@...sung.com" <k.debski@...sung.com>,
	"kgene@...nel.org" <kgene@...nel.org>,
	"jg1.han@...sung.com" <jg1.han@...sung.com>
Subject: Re: [PATCH 0/4] phy: samsung-usb2: Add support for Vbus regulator

On Thu, Dec 11, 2014 at 5:52 PM, David Laight <David.Laight@...lab.com> wrote:
> From: Vivek Gautam
>> This has been on my to-do list for sometime.
>> Until now the host controller (specifically ehci-exynos) is responsible
>> for enabling VBUS supply. This opens up one more issue which is, when
>> only ohci-exynos is enabled and ehci-exynosis disabled then VBUS was
>> never enabled (since ohci did not have the code to enabled the VBUS supply).
>>
>> Rather it should be wise to move the VBUS related stuff to phy driver and
>> let phy take care of enabling it.
>>
>> This patch series adds that VBUS regulator to phy-samsung-usb2 driver,
>> adds necessary binding information as well as vbus-supply properties
>> to phy nodes on exynos5250 systems.
> ...
>
> Does this go anyway to allowing devices to be powered from a micro-usb
> connector while acting as a USB host (USB OTG).
> ie when you want VBUS disabled even though it would normally
> need to be enabled.

Sorry i didn't get your second line.

This change allows HOST and HSIC phys to enable VBUS for the devices
connected to it.
Although now i think there can be a flaw in this approach
when only in OTG mode, when DEVICE phy is being used, even then
the regulator will be turned on causing power unnecessary consumption.




-- 
Best Regards
Vivek Gautam
Samsung R&D Institute, Bangalore
India
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