From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: Re: [PATCH 3/4] devicetree: bindings: Add defeature-repeated-start property for Cadence I2C Date: Tue, 2 Dec 2014 14:16:11 +0100 Message-ID: <20141202131611.GC4072@katana> References: <1417514749-24319-1-git-send-email-harinik@xilinx.com> <1417514749-24319-4-git-send-email-harinik@xilinx.com> <20141202111907.GC23671@leverpostej> <20141202125203.GA4072@katana> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="eHhjakXzOLJAF9wJ" Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Harini Katakam Cc: Mark Rutland , "grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org" , "robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" , Pawel Moll , "ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org" , "galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org" , "michal.simek-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org" , "soren.brinkmann-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "vishnum-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org" List-Id: devicetree@vger.kernel.org --eHhjakXzOLJAF9wJ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline > But given the bugs, it will be useful to just disable it if the system doesn't > require repeated start. What do you do when disable repeated start? Sending STOP and START? If so, this is really something different than repeated start. By using I2C_FUNC_I2C a user expects repeated start, so if the HW does not support it, we should say so and don't try to emulate it with something different. > If you think DT entry is not the way to go, do you think a CONFIG option or > something better will work? No, check at runtime if the transfer is possible on this HW. Bail out if not. > We chose a DT property because there is a good chance the user has multiple > cadence I2C controllers - one connected to a slave that needs repeated start > (like a power controller) and another that doesn't care. The user should not need to know with this level of detail if we can avoid it IMO. --eHhjakXzOLJAF9wJ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJUfbubAAoJEBQN5MwUoCm29vUP/joDQCiY2g+Bc/f63BDzYevg vlqzOgmZghenJ0flPZL06Tx2MQkIHXWVoMn4OisvNmXS0Z+15g7m6sZZCdfS14nj e/IjuUHR2vuwTIUbXZlxaBKqIqKsXfl0LYVHDr99aABD7iBfIIHzzKmYJ+uuR11g +Jo5CmW2HzfLz+tTBVS3ZuoM/e+vniuUWNIJsnCN5d4YY/TcBWUNgosPpf1/vp1J S0KDgJWbD6vIKUADrgz8t8LMUQb2YJbvG4F+BvT6rWb3LouBU0x5XiVdOmX56Cvy N5mGlqhzSMqOjIJ4NP7qK3o1bxCdU2F8sOlf6MRfIqX6Rs0SumNliDIc9s42CMPA cizhJ0EkxU2eff/pfsXxQSCJwxtX+Ul+ypA80Y9KE47c4//9OPJeE33i1tZdLJra 6ZrPXVpUyQO78DiaBa3FPaTmyBj3uuZ0X+qCeelFmLjt4JCNMtlTkmL64rMHr/Qw FEfqMga7HmJWnHGXmiAaasFzdXY4/CQPQG84qMAD+ffxFSZmuzfg3j8Ge7A0rjw7 koDWyh4tiwkOTJgFXbjl6K4goHalnwquYC6ArRnc1l0r7XVIBlcjfK43aKPNnK/j xwgWPb9f9pASB4GlMqUECHTrOX9psJezna5G3Q0ZzbUlqtDHHKjhATq864a3ewQ8 b87LjQUxtKyPHc+7G2jY =av0D -----END PGP SIGNATURE----- --eHhjakXzOLJAF9wJ--