linux-kernel - Re: [PATCH v7 1/2] usb: host: xhci-plat: Get PHYs for xhci's hcds

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Message-ID: <546A1F64.7000209@cogentembedded.com>
Date:	Mon, 17 Nov 2014 19:16:36 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Vivek Gautam <gautamvivek1987@...il.com>
CC:	Vivek Gautam <gautam.vivek@...sung.com>,
	Linux USB Mailing List <linux-usb@...r.kernel.org>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Greg KH <gregkh@...uxfoundation.org>, kishon <kishon@...com>,
	Felipe Balbi <balbi@...com>,
	Alan Stern <stern@...land.harvard.edu>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Mathias Nyman <mathias.nyman@...el.com>,
	Julius Werner <jwerner@...gle.com>,
	Jingoo Han <jg1.han@...sung.com>
Subject: Re: [PATCH v7 1/2] usb: host: xhci-plat: Get PHYs for xhci's hcds

Hello.

On 11/17/2014 9:36 AM, Vivek Gautam wrote:

>>> The host controller by itself may sometimes need to handle PHY
>>> and re-initialize it to re-configure some of the PHY parameters
>>> to get full support out of the PHY controller.
>>> Therefore, facilitate getting the two possible PHYs, viz.
>>> USB 2.0 type (UTMI+) and USB 3.0 type (PIPE3), and initialize them.

>>> Signed-off-by: Vivek Gautam <gautam.vivek@...sung.com>
>>> ---
>>>    drivers/usb/host/xhci-plat.c |   74
>>> ++++++++++++++++++++++++++++++++++++++++++
>>>    1 file changed, 74 insertions(+)

>>> diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
>>> index 3d78b0c..5207d5b 100644
>>> --- a/drivers/usb/host/xhci-plat.c
>>> +++ b/drivers/usb/host/xhci-plat.c
[...]
>>> @@ -204,6 +271,8 @@ static int xhci_plat_suspend(struct device *dev)
>>>          struct usb_hcd  *hcd = dev_get_drvdata(dev);
>>>          struct xhci_hcd *xhci = hcd_to_xhci(hcd);
>>>
>>> +       phy_exit(hcd->phy);

>>     Hm, in the suspend() method?

> phy_exit() should eventually be suspending the PHY and put it to
> low power state.

    I thought it's a role that the power_off() mothod should play, considering 
that the power_on() method gets called after the init() method....

> phy_init() in resume() will then take up the task of activating the
> PHY again.

> phy_power_on() and phy_power_off() are called at xhci_probe() and remove() time.

    Of course.

> Does this makes sense ?

    Not much, really.

WBR, Sergei

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