From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: Re: rcar-i2c: always reads a byte Date: Mon, 5 May 2014 17:51:44 +0200 Message-ID: <20140505155143.GB13467@katana> References: <531F3686.7050808@codethink.co.uk> <20140311164043.GA1179@katana> <531F3CD3.4030408@codethink.co.uk> <531F438D.80001@codethink.co.uk> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="GID0FwUMdk1T2AWN" Return-path: Content-Disposition: inline In-Reply-To: <531F438D.80001@codethink.co.uk> Sender: linux-sh-owner@vger.kernel.org To: Ben Dooks Cc: linux-i2c@vger.kernel.org, SH-Linux List-Id: linux-i2c@vger.kernel.org --GID0FwUMdk1T2AWN Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > >>>The system issues an address transaction followed by a single byte > >>>read. > >> > >>This fits to my observation that the rcar driver cannot do SMBUS_QUICK > >>(e.g. via i2cdetect). I assumed that handling a length of 0 is broken. I > >>haven't had a deeper look yet, so I can't say much. So, you either go > >>for it yourself, or you wait until I posted my IIC enablement series for > >>Lager. Then, you can switch to the IIC core with the sh_mobile driver. > >>That one does SMBUS_QUICK correctly. > > > >I'll have a deeper look into this, I think there may be a solution. >=20 > I've tried issuing the ESG + FSB bits as a command, however that > did not work. So, I experimented today as well. I don't think it is possible to have zero-length support. I'll cook up a patch to disable them. Come to think of it, it should be even for stable since I assume SMBUS_QUICK_WRITE will also put a byte on the bus. Not good! And I2C_M_NOSTART is also out of the question with this hardware. --GID0FwUMdk1T2AWN Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.15 (GNU/Linux) iQIbBAEBAgAGBQJTZ7OPAAoJEBQN5MwUoCm2o68P9j2zokQiV9ZjXK9FTh+N8Ikz URsgnOBtv8YLYksv0Ah/9qp6p1JVVqb9czlkVyp3UA84FffwmNeNM66MOZqr9MrV FMe4IO+fWFBlWYAbYnW7X625mFyZsvW0+KbpfFyJA2dUPCFa8qL7PzwEYSQNLCtI StjMwQilcbc8Vf8tbMEY4yNBa1LSEdn50bmLVLYWlPn2jcWRVmyqyfp41wFMJq8F AtIlvb+cEhXQX+vGXu3J58hTYtc0BWSDU/JmehtW1+B32E2m3TrbBmSfMAaJBsxf fIWPqDYKxowCN8rA6B4boed5ElbF6XtWJjlTXWYH12Lj3bJFTlefswsWeaBb24Cm xWCwRYdSn9oD8CHNJrZXqOxTkiw8YaKrCJrPWgKQiSAIPj0hcbbp1RarmnFJHa4Y 9ywT/TkC6vu2CbTEc2AQ4BYmuEAvO/6Q5rBWy/0owg9j0bqi/xSmLzDY9xAYlhx/ pKQJyoSkIddYCKRzIOjfvbW0mTaeBS0tvms2vx6gJQZOoeFkFDFFYPit24m3PMR6 oqAv9Hp1xapTAAd9KyA6A/l6ydqNRv1HNuwyZdfa1VWXOqxg3Ojy67Ma1iHg6CtV ZFY/n0YS6bfrL8VNUUWzp4qvdQRsXXuyfb+xN/HrQ+H1JWbLAqUpxZtd2wCj/hgX Dd/QLOzAzINC9iZtsYs= =rTJh -----END PGP SIGNATURE----- --GID0FwUMdk1T2AWN--