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From: Wolfram Sang <wsa@the-dreams.de>
To: Peter Rosin <peda@axentia.se>
Cc: linux-kernel@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Jonathan Cameron <jic23@kernel.org>,
	Hartmut Knaack <knaack.h@gmx.de>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
	Jonathan Corbet <corbet@lwn.net>, Arnd Bergmann <arnd@arndb.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-i2c@vger.kernel.org, devicetree@vger.kernel.org,
	linux-iio@vger.kernel.org, linux-doc@vger.kernel.org
Subject: Re: [PATCH v7 00/12] mux controller abstraction and iio/i2c muxes
Date: Sun, 8 Jan 2017 11:51:29 +0100	[thread overview]
Message-ID: <20170108105129.GB1983@katana> (raw)
In-Reply-To: <1483532187-28494-1-git-send-email-peda@axentia.se>

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Hi peda,

> One thing that I would like to do, but don't see a solution
> for, is to move the mux control code that is present in
> various drivers in drivers/i2c/muxes to this new minimalistic
> muxing subsystem, thus converting all present i2c muxes (but
> perhaps not gates and arbitrators) to be i2c-mux-simple muxes.

In a few lines, what is preventing that?

> I'm using an rwsem to lock a mux, but that isn't really a
> perfect fit. Is there a better locking primitive that I don't
> know about that fits better? I had a mutex at one point, but
> that didn't allow any concurrent accesses at all. At least
> the rwsem allows concurrent access as long as all users
> agree on the mux state, but I suspect that the rwsem will
> degrade to the mutex situation pretty quickly if there is
> any contention.

Maybe ask this question in a seperate email thread on lkml cc-ing the
locking gurus (with a pointer to this thread)?

> Also, the "mux" name feels a bit ambitious, there are many muxes
> in the world, and this tiny bit of code is probably not good
> enough to be a nice fit for all...

"... and it probably never will support anything other than
AT-harddisks, as that's all I have..." ;))

Thanks for this work!

   Wolfram


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  parent reply	other threads:[~2017-01-08 10:51 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-04 12:16 [PATCH v7 00/12] mux controller abstraction and iio/i2c muxes Peter Rosin
2017-01-04 12:16 ` [PATCH v7 02/12] dt-bindings: document devicetree bindings for mux-controllers and mux-gpio Peter Rosin
     [not found] ` <1483532187-28494-1-git-send-email-peda-koto5C5qi+TLoDKTGw+V6w@public.gmane.org>
2017-01-04 12:16   ` [PATCH v7 01/12] devres: trivial whitespace fix Peter Rosin
     [not found]     ` <1483532187-28494-2-git-send-email-peda-koto5C5qi+TLoDKTGw+V6w@public.gmane.org>
2017-01-07 22:29       ` Jonathan Cameron
2017-01-04 12:16   ` [PATCH v7 03/12] mux: minimal mux subsystem and gpio-based mux controller Peter Rosin
     [not found]     ` <1483532187-28494-4-git-send-email-peda-koto5C5qi+TLoDKTGw+V6w@public.gmane.org>
2017-01-08 10:23       ` Jonathan Cameron
2017-01-08 21:55         ` Peter Rosin
2017-01-04 12:16   ` [PATCH v7 10/12] i2c: i2c-mux-simple: new driver Peter Rosin
2017-01-08 10:44     ` Wolfram Sang
2017-01-04 12:16 ` [PATCH v7 04/12] dt-bindings: simplified bindings for single-user gpio mux Peter Rosin
2017-01-08 10:25   ` Jonathan Cameron
2017-01-04 12:16 ` [PATCH v7 05/12] mux: support " Peter Rosin
     [not found]   ` <1483532187-28494-6-git-send-email-peda-koto5C5qi+TLoDKTGw+V6w@public.gmane.org>
2017-01-05 16:21     ` Peter Rosin
2017-01-08 10:28       ` Jonathan Cameron
2017-01-08 21:56         ` Peter Rosin
2017-01-10 21:22           ` Jonathan Cameron
2017-01-04 12:16 ` [PATCH v7 06/12] iio: inkern: api for manipulating ext_info of iio channels Peter Rosin
2017-01-04 12:16 ` [PATCH v7 07/12] dt-bindings: iio: iio-mux: document iio-mux bindings Peter Rosin
     [not found]   ` <1483532187-28494-8-git-send-email-peda-koto5C5qi+TLoDKTGw+V6w@public.gmane.org>
2017-01-08 10:29     ` Jonathan Cameron
2017-01-04 12:16 ` [PATCH v7 08/12] iio: multiplexer: new iio category and iio-mux driver Peter Rosin
2017-01-04 12:16 ` [PATCH v7 09/12] dt-bindings: i2c: i2c-mux-simple: document i2c-mux-simple bindings Peter Rosin
2017-01-07 22:28   ` Jonathan Cameron
2017-01-04 12:16 ` [PATCH v7 11/12] dt-bindings: mux-adg792a: document devicetree bindings for ADG792A/G mux Peter Rosin
2017-01-08 10:31   ` Jonathan Cameron
2017-01-04 12:16 ` [PATCH v7 12/12] mux: adg792a: add mux controller driver for ADG792A/G Peter Rosin
2017-01-08 10:32   ` Jonathan Cameron
2017-01-08 10:51 ` Wolfram Sang [this message]
2017-01-08 21:56   ` [PATCH v7 00/12] mux controller abstraction and iio/i2c muxes Peter Rosin

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