Subject: [linux-sunxi] [PATCH 1/4] ARM: dts: sunxi: Add regulator-boot-on to usb host port regulator nodes

From: [email-masked] (Maxime Ripard)
Date: Thu, 25 Jun 2015 13:12:05 +0200

On Tue, Jun 23, 2015 at 10:19:10AM +0200, Hans de Goede wrote:
> Hi,
> 
> On 23-06-15 09:16, Maxime Ripard wrote:
> >On Mon, Jun 22, 2015 at 10:28:16AM +0200, Hans de Goede wrote:
> >>Hi,
> >>
> >>On 22-06-15 02:30, Julian Calaby wrote:
> >>>Hi Hans,
> >>>
> >>>On Sun, Jun 21, 2015 at 1:40 AM, Hans de Goede <[email-masked]> wrote:
> >>>>u-boot will have turned on the power to the usb host ports, so mark them
> >>>>as regulator-boot-on, this stops the power on the ports from temporarily
> >>>>getting turned off during boot, causing issues with e.g. usb powered
> >>>>harddisks.
> >>>
> >>>Stupid question: shouldn't u-boot set this property?
> >>
> >>We could make u-boot set this property but that will require a lot of code on
> >>u-boot's side which is simply not there atm. And traditionally this property
> >>is is simply a part of the dts files as shipped with the kernel.
> >
> >What happens if the property is set but the regulator is not actually
> >enabled?
> 
> Then its gets enabled when the regulator loads, so assuming that the usb driver
> is enabled in the kernel config 0.5 (built-in) - 3 (module) seconds earlier then
> it otherwise would.

Ok, perfect then.

> This is not a problem since usb-ports are normally always powered anyways

That might be true using mainline u-boot, but might not be on other
bootloaders, hence why I asked that.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 819 bytes
Desc: Digital signature
URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20150625/3954901b/attachment-0001.sig>