linux-kernel - Re: [PATCH] usb: dwc3: core: power on PHYs before initializing core

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Message-ID: <20180308164916.GA65031@rodete-desktop-imager.corp.google.com>
Date:   Thu, 8 Mar 2018 08:49:18 -0800
From:   Brian Norris <briannorris@...omium.org>
To:     Felipe Balbi <balbi@...nel.org>
Cc:     William Wu <william.wu@...k-chips.com>, gregkh@...uxfoundation.org,
        Roger Quadros <rogerq@...com>, heiko@...ech.de,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-rockchip@...ts.infradead.org, frank.wang@...k-chips.com,
        huangtao@...k-chips.com, dianders@...gle.com,
        briannorris@...gle.com, groeck@...gle.com,
        daniel.meng@...k-chips.com, John.Youn@...opsys.com,
        lin.huang@...k-chips.com
Subject: Re: [PATCH] usb: dwc3: core: power on PHYs before initializing core

Hi,

On Thu, Mar 08, 2018 at 12:43:40PM +0200, Felipe Balbi wrote:
> William Wu <william.wu@...k-chips.com> writes:
> > The dwc3_core_init() gets the PHYs and initializes the PHYs with
> > the usb_phy_init() and phy_init() functions before initializing
> > core, and power on the PHYs after core initialization is done.
> >
> > However, some platforms (e.g. Rockchip RK3399 DWC3 with Type-C
> > USB3 PHY), it needs to do some special operation while power on
> > the Type-C PHY before initializing DWC3 core. It's because that
> > the RK3399 Type-C PHY requires to hold the DWC3 controller in
> > reset state to keep the PIPE power state in P2 while configuring
> > the Type-C PHY, otherwise, it may cause waiting for the PIPE ready
> > timeout. In this case, if we power on the PHYs after the DWC3 core
> > initialization is done, the core will be reset to uninitialized
> > state after power on the PHYs.
> >
> > Fix this by powering on the PHYs before initializing core. And
> > because the GUID register may also be reset in this case, so we
> > need to configure the GUID register after powering on the PHYs.
> >
> > Signed-off-by: William Wu <william.wu@...k-chips.com>
> 
> does this cause any regressions for your boards?

I'm not Roger, but I believe it was determined we don't need this for
the Rockchip systems for which William was originally sending this. At
least not right now. I believe our PHY init problems were mostly
resolved in other ways.

(Although I hear USB is currently pretty broken around suspend/resume
for us on -next. Likely unrelated.)

I guess we never clearly replied stating the above. I hope this isn't
merged anywhere? Or I guess it's no problem to me at the moment, but it
might be needless churn.

Brian