From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: Re: [PATCH 21/66] rtl2830: implement own I2C locking Date: Mon, 2 Feb 2015 21:33:24 +0100 Message-ID: <20150202203324.GA11486@katana> References: <1419367799-14263-1-git-send-email-crope@iki.fi> <1419367799-14263-21-git-send-email-crope@iki.fi> <20150202180726.454dc878@recife.lan> <54CFDCCC.3030006@iki.fi> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="tKW2IUtsqtDRztdT" Return-path: Content-Disposition: inline In-Reply-To: <54CFDCCC.3030006-X3B1VOXEql0@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Antti Palosaari Cc: Mauro Carvalho Chehab , Mark Brown , Lars-Peter Clausen , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Jean Delvare List-Id: linux-i2c@vger.kernel.org --tKW2IUtsqtDRztdT Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > >Ok, this may eventually work ok for now, but a further change at the I2C > >core could easily break it. So, we need to double check about such > >patch with the I2C maintainer. > > > >Jean, > > > >Are you ok with such patch? If so, please ack. Jean handed over I2C to me in late 2012 :) > Basic problem here is that I2C-mux itself is controlled by same I2C device > which implements I2C adapter for tuner. >=20 > Here is what connections looks like: > ___________ ____________ ____________ > | USB IF | | demod | | tuner | > |-----------| |------------| |------------| > | |--I2C--|-----/ -----|--I2C--| | > |I2C master | | I2C mux | | I2C slave | > |___________| |____________| |____________| >=20 >=20 > So when tuner is called via I2C, it needs recursively call same I2C adapt= er > which is already locked. More elegant solution would be indeed nice. So, AFAIU this is the same problem that I2C based mux devices have (like drivers/i2c/muxes/i2c-mux-pca954x.c)? They also use the unlocked transfers... --tKW2IUtsqtDRztdT Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJUz98UAAoJEBQN5MwUoCm2BccP/RV44szd9ocf8LtYppv7c4do Gvg9shTDCBVSJVTs6iBhgFjU3MCzvmqcP9ZTSpAmH6xHdD5bPq+O8TztjSlhHjeR dOHaC/bWhtlBVYSiUnR26jc1EDtVhVeNmeiiRMRRASnb8lqwEXUiUNkT6LOiygfC rNmaqfAb8B+boX3yODbx29SjMpjtAOcbOXSU+ABNU2Bc+3SzItwtXCilCL4/s3Ob ow8Ngyo2Wri6dWryo4Q71+bOlYbZVNUwa9iJpxKURnZ6PHWfGQhTM95j+thP5M75 TWBrnwaGg22vjH5xK/7rBmGFMqLHeya2kTuvgFnjELIBP9trUaiLYgAi9A5rq7Vx Urf9SUxJM0McaksjB7o0ecw+YDELbm/y9v4OoNQzqaErnO1X0BfXHXYb0jB77qQf cin/7q4ApXlplGf+CF/SkERKMqfA/TxFe6m0Lvnh/2jh1NCQUfRbGCOeyDqFvQyM QJiHV4SHVTgCFq7aCdoaLeGSPprm64rxrTb1Tf/hR5r5cmCTSMQu+j9pMSQTtNxT zFasSviPp95ztSUFmC9rLMGe06sjDM57+OvtN/ejoWNrA0X8H+sAnKauzbOBlxei ZMyWMWbFCbSFBP1yb08DL7+w8AnSAJEPjWulk+VYmw7Rxlf8tktwMkvcsLpGR7w+ 2RJPHeX7v+pUNgCeqChT =dDU1 -----END PGP SIGNATURE----- --tKW2IUtsqtDRztdT--