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 13:48:39 +0200
From:   "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
To:     Pawel Laszczak <pawell@cadence.com>
Cc:     Pavel Machek <pavel@ucw.cz>,
        "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: <20190722114839.GA10515@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>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <BYAPR07MB470904ACCD1ED91B10BB6BEFDDC40@BYAPR07MB4709.namprd07.prod.outlook.com>
User-Agent: Mutt/1.12.1 (2019-06-15)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, Jul 22, 2019 at 09:58:42AM +0000, Pawel Laszczak 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.

thanks,

greg k-h