linux-kernel - Re: [PATCH 1/2] usb: dwc3: core: continue probing if usb phy library returns -ENODEV/-ENXIO

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <52E27408.8060808@ti.com>
Date:	Fri, 24 Jan 2014 19:39:12 +0530
From:	Kishon Vijay Abraham I <kishon@...com>
To:	<balbi@...com>
CC:	<george.cherian@...com>, <heikki.krogerus@...ux.intel.com>,
	<rogerq@...com>, <devicetree@...r.kernel.org>,
	<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-omap@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-usb@...r.kernel.org>
Subject: Re: [PATCH 1/2] usb: dwc3: core: continue probing if usb phy library
 returns -ENODEV/-ENXIO

Hi,

On Tuesday 21 January 2014 08:17 PM, Felipe Balbi wrote:
> On Tue, Jan 21, 2014 at 03:41:38PM +0530, Kishon Vijay Abraham I wrote:
>> Since PHYs for dwc3 is optional (not all SoCs that have DWC3 use PHYs),
>> do not return from probe if the USB PHY library returns -ENODEV as that
> 
> this isn't correct, they all have PHYs, some of them might not be
> controllable.

right, but we use USB PHY library only for controllable PHYs (apart from using
nop).
> 
>> indicates the platform does not have PHY.
> 
> not really, that indicates the current platform tried to grab a PHY and
> the PHY doesn't exist. If there's anybody with a non-controllable PHY
> and someone gives me a really good reason for not using the generic
> no-op PHY, then we should add a flag and we could:
> 
> 	if (!likely(dwc->flags & DWC3_USB2PHY_DRIVER_NOT_NEEDED))
> 		dwc3_grab_phys(dwc);
> 
> But I really want to see the argument against using no-op. As far as I
> could see, everybody needs a PHY driver one way or another, some
> platforms just haven't sent any PHY driver upstream and have their own
> hacked up solution to avoid using the PHY layer.

I was trying to address Heikki concerns in my previous version [1] where I used
quirks to identify if the platform does not have PHY.

[1] -> https://lkml.org/lkml/2013/12/5/32

Thanks
Kishon
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/