linux-kernel - Re: [PATCH v14 00/11] mux controller abstraction and iio/i2c muxes

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Message-ID: <1493045969.2446.47.camel@pengutronix.de>
Date:   Mon, 24 Apr 2017 16:59:29 +0200
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     Peter Rosin <peda@...ntia.se>
Cc:     Jonathan Cameron <jic23@...nel.org>, linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Jonathan Corbet <corbet@....net>, linux-i2c@...r.kernel.org,
        devicetree@...r.kernel.org, linux-iio@...r.kernel.org,
        linux-doc@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Colin Ian King <colin.king@...onical.com>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        kernel@...gutronix.de
Subject: Re: [PATCH v14 00/11] mux controller abstraction and iio/i2c muxes

On Mon, 2017-04-24 at 16:36 +0200, Peter Rosin wrote:
[...]
> > How about an atomic use_count on the mux_control, a bool shared that is
> > only set by the first consumer, and controls whether selecting locks?
> 
> That has the drawback that it is hard to restore the mux-control in a safe
> way so that exclusive consumers are allowed after the last shared consumer
> puts the mux away.

True.

> Agreed, it's a corner case, but I had this very similar
> patch going through the compiler when I got this mail. Does it work as well
> as what you suggested?

Yes, this patch works just as well.

regards
Philipp