linux-kernel - Re: [PATCH 3/8] usb: typec: mux: Get the mux identifier from function parameter

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Message-ID: <20180709190310.GC1896@roeck-us.net>
Date:   Mon, 9 Jul 2018 12:03:10 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Hans de Goede <hdegoede@...hat.com>, Jun Li <jun.li@....com>,
        Mats Karrman <mats.dev.list@...il.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/8] usb: typec: mux: Get the mux identifier from
 function parameter

On Thu, Jun 28, 2018 at 02:34:27PM +0300, Heikki Krogerus wrote:
> On Thu, Jun 28, 2018 at 07:51:55PM +0900, Greg Kroah-Hartman wrote:
> > On Wed, Jun 27, 2018 at 06:19:48PM +0300, Heikki Krogerus wrote:
> > > In order for the muxes to be usable with alternate modes,
> > > the alternate mode devices will need also to be able to get
> > > a handle to the muxes on top of the port devices. To make
> > > that possible, the muxes need to be possible to request with
> > > an identifier.
> > > 
> > > This will change the API so that the mux identifier is given
> > > as a function parameter to typec_mux_get(), and the hard-coded
> > > "typec-mux" is replaced with that value.
> > > 
> > > Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> > > ---
> > >  drivers/usb/typec/class.c     | 2 +-
> > >  drivers/usb/typec/mux.c       | 6 +++---
> > >  include/linux/usb/typec_mux.h | 2 +-
> > >  3 files changed, 5 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/drivers/usb/typec/class.c b/drivers/usb/typec/class.c
> > > index 2b3eaa969f3b..b860bd3a0acb 100644
> > > --- a/drivers/usb/typec/class.c
> > > +++ b/drivers/usb/typec/class.c
> > > @@ -1357,7 +1357,7 @@ struct typec_port *typec_register_port(struct device *parent,
> > >  		goto err_switch;
> > >  	}
> > >  
> > > -	port->mux = typec_mux_get(cap->fwnode ? &port->dev : parent);
> > > +	port->mux = typec_mux_get(parent, "typec-mux");
> > 
> > This changes the first parameter for this call, is that ok?  Doesn't
> > that change the functionality here?
> 
> No, I noticed that cap->fwnode is set after we call that function, so
> we always ended up using parent.
> 
> This needs to be fixed properly of course, but I choose not to propose
> anything in this series. We don't yet use the fwnode handle with the
> muxes in any case, as the device connection API does not support
> anything else except build-in connections descriptions for now.
> 

Seems to me that would be better handled in a separate patch or patch
series. With this patch, the code ends up always using parent here but
there is still
	port->sw = typec_switch_get(cap->fwnode ? &port->dev : parent);
a couple of lines above. This is at the very least confusing to the
reader.

Guenter