From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Thierry Reding <treding@nvidia.com>
Cc: Chunfeng Yun <chunfeng.yun@mediatek.com>,
Liam Girdwood <lgirdwood@gmail.com>,
Mark Brown <broonie@kernel.org>,
Matthias Brugger <matthias.bgg@gmail.com>,
Paul Cercueil <paul@crapouillou.net>,
Lee Jones <lee.jones@linaro.org>,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-mediatek@lists.infradead.org
Subject: Re: [PATCH v2 3/3] Revert "usb: common: usb-conn-gpio: Make VBUS supply optional"
Date: Fri, 21 May 2021 20:06:13 +0200 [thread overview]
Message-ID: <YKf2ldQhJCVbR3N8@kroah.com> (raw)
In-Reply-To: <YKezl0nlWFQhLyf/@orome.fritz.box>
On Fri, May 21, 2021 at 03:20:23PM +0200, Thierry Reding wrote:
> On Wed, May 19, 2021 at 02:39:46PM +0800, Chunfeng Yun wrote:
> > Vbus is already an optional supply, if the vbus-supply is not
> > provided in DTS, will use a dummy regulator,
>
> That statement is not entirely correct. The dummy regulator is
> substituted only if the supply is in fact not optional. The idea behind
> that is to allow DTS files that don't specify all required regulators to
> get away with it, based on the assumption that the supply is one of
> those always-on supplies that are often not described in DTS.
>
> > the warning log is as below:
> > "supply vbus not found, using dummy regulator"
>
> And the reason why we get that warning is to point out that the DTS has
> a bug and that it should be fixed (by adding a proper regulator to take
> the place of the dummy).
>
> > This reverts commit 4ddf1ac79e5f082451cd549283d2eb7559ab6ca9.
>
> But if you read the description of that commit, the purpose of that
> patch was in fact to make the supply completely optional in the case
> where we already have the VBUS supply specified for the USB port that
> the connector is parented to.
>
> So in that case the DTS doesn't have the bug because the VBUS supply is
> already specified for the USB port and therefore it doesn't have to be
> specified in the USB connector again. In fact, specifying it twice can
> lead to a situation where the USB port may not be able to switch the
> VBUS supply on or off because the setting might conflict with that of
> the USB connector.
>
> So unless there's a real reason why this is needed, I don't think this
> should be applied.
I've dropped this from my tree now, thanks.
greg k-h
next prev parent reply other threads:[~2021-05-21 18:06 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-19 6:39 [PATCH v2 1/3] usb: common: usb-conn-gpio: fix NULL pointer dereference of charger Chunfeng Yun
2021-05-19 6:39 ` [PATCH v2 2/3] usb: common: usb-conn-gpio: use dev_err_probe() to print log Chunfeng Yun
2021-05-19 6:39 ` [PATCH v2 3/3] Revert "usb: common: usb-conn-gpio: Make VBUS supply optional" Chunfeng Yun
2021-05-21 13:20 ` Thierry Reding
2021-05-21 18:06 ` Greg Kroah-Hartman [this message]
2021-05-24 5:51 ` Chunfeng Yun
2021-05-25 11:36 ` Thierry Reding
2021-05-26 1:44 ` Chunfeng Yun
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