linux-kernel - Re: [PATCH 02/11] tpm/tpm_i2c_infineon: switch to i2c_lock

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Date:   Tue, 19 Jun 2018 15:05:50 +0200
From:   Peter Rosin <peda@...ntia.se>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org, Peter Huewe <peterhuewe@....de>,
        Jason Gunthorpe <jgg@...pe.ca>, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Brian Norris <computersforpeace@...il.com>,
        Gregory Fong <gregory.0xf0@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        bcm-kernel-feedback-list@...adcom.com,
        Sekhar Nori <nsekhar@...com>,
        Kevin Hilman <khilman@...nel.org>,
        Haavard Skinnemoen <hskinnemoen@...il.com>,
        Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Orson Zhai <orsonzhai@...il.com>,
        Baolin Wang <baolin.wang@...aro.org>,
        Chunyan Zhang <zhang.lyra@...il.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Wolfram Sang <wsa@...-dreams.de>,
        Guenter Roeck <linux@...ck-us.net>, Crt Mori <cmo@...exis.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Antti Palosaari <crope@....fi>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Michael Krufky <mkrufky@...uxtv.org>,
        Lee Jones <lee.jones@...aro.org>,
        linux-integrity@...r.kernel.org, linux-i2c@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-iio@...r.kernel.org, linux-input@...r.kernel.org,
        linux-media@...r.kernel.org
Subject: Re: [PATCH 02/11] tpm/tpm_i2c_infineon: switch to i2c_lock_segment

On 2018-06-19 14:56, Jarkko Sakkinen wrote:
> On Fri, Jun 15, 2018 at 12:14:57PM +0200, Peter Rosin wrote:
>> Locking the root adapter for __i2c_transfer will deadlock if the
>> device sits behind a mux-locked I2C mux. Switch to the finer-grained
>> i2c_lock_segment. If the device does not sit behind a mux-locked mux,
>> the two locking variants are equivalent.
>>
>> Signed-off-by: Peter Rosin <peda@...ntia.se>
> 
> Can you quickly explain (or give a reference) the difference with these
> functions? Not an expert in this area. Thanks.

There are some words in the cover letter. If you need more, there's
always Documentation/i2c/i2c-topology. Hope that helps, otherwise I'll
try to explain better...

Cheers,
Peter