From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: Re: [PATCH] i2c: cadence: Handling Slave monitor mode Date: Thu, 2 Apr 2015 22:29:09 +0200 Message-ID: <20150402202909.GA3501@katana> References: <20150327153713.GC27238@katana> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="LQksG6bCIzRHxTLp" Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Harini Katakam Cc: Nava kishore Manne , Michal Simek , =?utf-8?B?U8O2cmVu?= Brinkmann , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , anirudh-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org, svemula-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org, Nava kishore Manne List-Id: linux-i2c@vger.kernel.org --LQksG6bCIzRHxTLp Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > >> In slave monitor mode, the I2C interface is set up as a master and > >> continues to attempt a transfer to a particular slave until the > >> slave device responds with an ACK. > >> > >> Added this feature for zero length transfers enable the controller > >> for slave monitor interrupt and get the status. Disable the slave > >> monitor mode feature upon successful handling. > >> > >> Signed-off-by: Nava kishore Manne > >> Acked-by: Harini Katakam > > > > I am not sure this is going to work. > > > > How often is this access tried when there is no device? It should be > > tried only once. >=20 > Once slave monitor is enabled in the host controller, it retries till the= re's an > ACK or slave monitor is disabled. The SW wont be involved and need not So, it is kind of flooding the bus until the timeout? That is not a single zero byte message. > be interrupted in this gap. The way this feature works in the controller = though, > I'm afraid there's no way to distinguish between no slave/ busy slave. > The out is the software timeout in that case. > Please suggest how to use this feature better. I suggest to not use the feature and accept that this device cannot do zero byte length messages. Thanks, Wolfram --LQksG6bCIzRHxTLp Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJVHaaVAAoJEBQN5MwUoCm23kEP/2W0f9Rg9DLF+nQo/0PSbO+n sbzZ4FD5ZrS+ChNR/jLAnw5cSrB/OOy3Nz92AOZExh91k71SDz3YQS3+cfhp/QxD fnaiwb/u19Z7aJNXWxHatyNzneEUAvfrA8mQsVRIXGXO5Xy1lFD5mdeURq3sMcUo YIbgahQzRY8tb23XW/yTJQfrbMMQ53nxTeWS52qYes8tysTOFnIESW37ry8Lrlgo CArRXlVdsRluc0v8TCocsELgWZqHklhp03+xD7C3GQPZ0lt5ZjzRVDCwJMnFg6Ei cqtmZhPPA7fNi71Xs6XBCr65ijLhtpdWyx20lYc9HB1I5GFRlmCy1/wzWOZ0Dt8e uTRvq1/rqCZ78eOy7J3hrSvSQtuFDfdEdNBtGoKfeYVcGUR1yh3wee51hKpbdGZX oeMaz07g3XHMv/65W048A+P+yuq9ZLo3/5vOBYYQeIUdZWTK8MfJ0I/A3J6BT5TV IvdbPtaRBRJck8vlDmKJTJmpHjdOzmTYTbEgtuIabMeXvwwb4/xrhfd3fmlQPwlf FoLAwmQke6dWjtYwA0mmNhfWlkiUOE+ftdsvkozrvoV+oP3zw9Ft0omTF8qaNQr/ 2s7WWhEfl1W9Wh6TaT7PpaXdpTv8lc1jN0k7C5uid50YEke/LKII+xIyqD8NdVvO s3q1alrYQDeiYRVqx0yD =rOzs -----END PGP SIGNATURE----- --LQksG6bCIzRHxTLp--