Date: Fri, 16 Nov 2012 07:01:18 -0800
From: Greg KH <gregkh@linuxfoundation.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Jun Chen <jun.d.chen@intel.com>, serial <linux-serial@vger.kernel.org>,
        "russ.gorby" <russ.gorby@intel.com>,
        liu chuansheng <chuansheng.liu@intel.com>,
        Linux Kernel <linux-kernel@vger.kernel.org>,
        Bi Chao <chao.bi@intel.com>, Alan Cox <alan@linux.intel.com>
Subject: Re: [PATCH] serial: ifx6x60: Add module parameters to manage the
 modem status through sysfs
Message-ID: <20121116150118.GA26219@kroah.com>
References: <1353070789.24092.6.camel@chenjun-workstation>
 <20121116123806.GA9303@kroah.com>
 <20121116150007.273b7038@pyramind.ukuu.org.uk>
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On Fri, Nov 16, 2012 at 03:00:07PM +0000, Alan Cox wrote:
> On Fri, 16 Nov 2012 04:38:06 -0800
> Greg KH <gregkh@linuxfoundation.org> wrote:
> 
> > On Fri, Nov 16, 2012 at 07:59:49AM -0500, Jun Chen wrote:
> > > 
> > > The Medfield Platform implements a recovery procedure consisting in an escalation
> > > from simple and light recovery procedures to stronger ones with increased visibility
> > > and impact to end-user.After platform find some problem from Modem,such as no response,
> > > platform will try do modem warm reset.If several tries failed, platform will try to
> > > do modem cold boot procedure.For Modem Cold Boot, AP is responsible to generate
> > > blob (binary object containing PIN code and other necessary information).
> > > Blob is stored in AP volatile memory. AP decides to read PIN code from cache instead of
> > > prompting end-user, and sends it to modem as if end-user had entered it.
> > > 
> > > This patch add module parameters to manage the modem status through sysfs.
> > > Reset_modem can be read and write by user space.When read the reset_modem,user space will
> > > get the mdm_reset_state which used to avoid to run twice at once.When set the reset_modem to
> > > IFX_COLD_RESET_REQ,modem will do cold reset, other val value will trigger modem reset.
> > > 
> > > Hangup_reasons used to give one interface to user space to know and clear the modem reset reasons.
> > > Now there are four reasons:SPI timeout, modem initiative reset,modem coredump,spi tranfer error.
> > 
> > Why are these module parameters?  Why not just "real" sysfs files
> > instead?  That way, if you have multiple devices in a system, it will
> > work properly for them.  Right now you are limited to 1 device, right?
> 
> Yes and its highly unlikely that there will ever be anyone who needs two.

Ok, but why a module parameter?  That's a very "odd" way to do this type
of interaction, why not just a "normal" sysfs file instead?

Either way, there's no documentation here, which is needed for a new
kernel/user api that is being created.  Someone needs to add an entry
for Documentation/ABI/ here.

thanks,

greg k-h
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