linux-kernel - Re: [PATCH] usb: phy: Cleanup error code in **_usb_get_phy

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Date:	Mon, 19 Aug 2013 11:00:53 -0700
From:	Julius Werner <jwerner@...omium.org>
To:	Vivek Gautam <gautamvivek1987@...il.com>
Cc:	Julius Werner <jwerner@...omium.org>,
	Vivek Gautam <gautam.vivek@...sung.com>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Alan Stern <stern@...land.harvard.edu>,
	Felipe Balbi <balbi@...com>, kishon <kishon@...com>
Subject: Re: [PATCH] usb: phy: Cleanup error code in **_usb_get_phy_**() APIs

>> I liked the ones where we had IS_ERR_OR_NULL() here (and in all the
>> ones below)... you sometimes have to handle PHYs in
>> platform-independent code where you don't want to worry about if this
>> platform actually has a PHY driver there or not. Any reason you
>> changed that?
>
> The **get_phy_*() APIs never return a NULL pointer now, do we still
> need to handle that in that case.
> Or are we assuming that code will use these phy operations without
> getting a phy in the first place ?

In our 5420 PHY tune patch (which I think has not made it upstream
yet), we're calling usb_phy_tune(hcd->phy) from the USB core. This
pointer is usually NULL unless it has been explicitly set by the
platform specific HCD driver. For situations like that I think it's
convenient if you can just fire-and-forget a generic PHY method
without worrying whether the particular PHY implements it or whether
it has a driver at all.
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