From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: Re: at24: writing with SMBUS and no I2C_FUNC_SMBUS_WRITE_I2C_BLOCK Date: Wed, 5 Mar 2014 21:15:53 +0100 Message-ID: <20140305201553.GA2571@katana> References: <20140305183305.GS27140@cumulusnetworks.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="y0ulUmNC+osPPQO6" Return-path: Content-Disposition: inline In-Reply-To: <20140305183305.GS27140-qUQiAmfTcIp+XZJcv9eMoEEOCMrvLtNR@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Curt Brune Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-i2c@vger.kernel.org --y0ulUmNC+osPPQO6 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > The notion of "slow" seems a bit arbitrary to me. Is there some other > technical reason or gotcha hiding here that you know of? $ git show 7aeb96642f70139a194d685b132605836f6f8dbb commit 7aeb96642f70139a194d685b132605836f6f8dbb Author: Jean Delvare Date: Fri May 21 18:40:57 2010 +0200 at24: Fall back to byte or word reads if needed =20 Increase the portability of the at24 driver by letting it read from EEPROM chips connected to cheap SMBus controllers that support neither raw I2C messages nor even I2C block reads. All SMBus controllers should support either word reads or byte reads, so read support becomes universal, much like with the legacy "eeprom" driver. =20 Obviously, this only works with EEPROM chips up to AT24C16, that use 8-bit offset addressing. 16-bit offset addressing is almost impossible to support on SMBus controllers. =20 I did not add universal support for writes, as I had no immediate need for this, but it could be added later if needed (with the same performance issue as byte and word reads have, of course.) =20 Signed-off-by: Jean Delvare Reviewed-by: Wolfram Sang Cc: Konstantin Lazarev > Would a nicely written patch that adds write support for this case be > acceptable? I have not written it yet, but would like to. Yes, it would. All the best, Wolfram --y0ulUmNC+osPPQO6 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.15 (GNU/Linux) iQIcBAEBAgAGBQJTF4X5AAoJEBQN5MwUoCm27BwQAKTHyEk67OYUI7CWmHw7uw+p G8WcsDCvZfp12hT2ECdcv8dHKXNVhRxg8Bm5cgRuG3731XLoXJ5qgF5Wre22ZtLt R0AdwjZbG4CH106XksxqejHd93WKfiSYUNQZ70l3mZKli9HAsZ5dy0bz/AjWSo1o LdvgPBogDGUm9nL+IkUnpueGsZO/izDisL1f3Ouc7HlKVplQV83ug8f+FVRWv5ha PSamF932nio7oGbvyTLv9phGEfT3GmOEuj5LO0TVfeTQY2SapW1MN08dw/OdzppI C+Onz8EMOefqMnf0S8iu85k/l1Q5Apxl5mXjIm3QYKYtVCqoZVP7vI/1wwbUGEPR s21fluZmf1z/PpRcWFkWyNe3yJSLuBtkOQWRCPbsUV+tvFfBhcH4KY6NfBbXJkAg enTZvSYuapr/b1wEp6g8kyNGltmuCA9cPhFrdNYctqKWvLZoJR1oj1sV2ORvoSi1 ETlYNmSMxNWQckNpEtX4RqYabF6zwWSjCqeQplRwNaSvq8W8SYVq6OKiq3jVsvhZ zWX5AEoxYuMdEYMfGHV+T9T7ybayHYGwZOhAGyJVq8U5VM2dLicZPm3W8RblMSbA VT+NvZx8Aq6HEF/pLmyNAYWMEj6M6pq5E+LuCSNvVE8tBABZNetqsb7ZTJKCVFCZ xDyYvTF69YZ4Y1FAD56E =l5Fy -----END PGP SIGNATURE----- --y0ulUmNC+osPPQO6--