Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Mon, 22 Jul 2019 14:11:18 +0200
From:   "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
To:     Pavel Machek <pavel@denx.de>
Cc:     Pawel Laszczak <pawell@cadence.com>,
        "felipe.balbi@linux.intel.com" <felipe.balbi@linux.intel.com>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        "rogerq@ti.com" <rogerq@ti.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "jbergsagel@ti.com" <jbergsagel@ti.com>,
        "nsekhar@ti.com" <nsekhar@ti.com>, "nm@ti.com" <nm@ti.com>,
        Suresh Punnoose <sureshp@cadence.com>,
        Jayshri Dajiram Pawar <jpawar@cadence.com>,
        Rahul Kumar <kurahul@cadence.com>,
        Anil Joy Varughese <aniljoy@cadence.com>
Subject: Re: [PATCH v10 0/6] Introduced new Cadence USBSS DRD Driver.
Message-ID: <20190722121118.GA31543@kroah.com>
References: <1563733939-21214-1-git-send-email-pawell@cadence.com>
 <20190721190335.GA19831@xo-6d-61-c0.localdomain>
 <BYAPR07MB470904ACCD1ED91B10BB6BEFDDC40@BYAPR07MB4709.namprd07.prod.outlook.com>
 <20190722114839.GA10515@kroah.com>
 <20190722115644.GA12069@amd>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20190722115644.GA12069@amd>
User-Agent: Mutt/1.12.1 (2019-06-15)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, Jul 22, 2019 at 01:56:45PM +0200, Pavel Machek wrote:
> Hi!
> 
> > > >> This patch introduce new Cadence USBSS DRD driver to linux kernel.
> > > >>
> > > >> The Cadence USBSS DRD Controller is a highly configurable IP Core which
> > > >> can be instantiated as Dual-Role Device (DRD), Peripheral Only and
> > > >> Host Only (XHCI)configurations.
> > > >
> > > >I see you are using debugfs to select between DRD, peripheral-onlyh and XHCI...
> > > >
> > > >Is that good idea?
> > > 
> > > Yes driver allows selecting dr_mode by debugfs. Controller also support such functionality 
> > > so I don't understand why would it not be a good idea. 
> > > 
> > > I personally use this for testing but it can be used to limit controller functionality without 
> > > recompiling kernel. 
> > 
> > debugfs is ONLY for debugging, never rely on it being enabled, or
> > mounted, on a system in order to have any normal operation happen.
> > 
> > So for testing, yes, this is fine.  If this is going to be the normal
> > api/interface for how to control this driver, no, that is not acceptable
> > at all.
> 
> It makes a lot of sense for end-user to toggle this... for example
> when he is lacking right cable for proper otg detection. As it is
> third driver offering this functionality, I believe we should stop
> treating it as debugging.

Then it needs to get out of debugfs, as again, that can not be used for
any normal end-user operation.

thanks,

greg k-h