From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: Re: [PATCH v3 4/5] i2c: davinci: use bus recovery infrastructure Date: Fri, 3 Apr 2015 22:18:46 +0200 Message-ID: <20150403201846.GH2016@katana> References: <1417448047-15236-1-git-send-email-grygorii.strashko@ti.com> <1417448047-15236-5-git-send-email-grygorii.strashko@ti.com> <20150318203151.GA12072@katana> <550C67D6.3080909@linaro.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="nFBW6CQlri5Qm8JQ" Return-path: Content-Disposition: inline In-Reply-To: <550C67D6.3080909-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Grygorii.Strashko-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org" Cc: Sekhar Nori , Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Kevin Hilman , Santosh Shilimkar , Murali Karicheri , Alexander Sverdlin List-Id: linux-i2c@vger.kernel.org --nFBW6CQlri5Qm8JQ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > > The I2C specs say in 3.1.16 that the recovery procedure should be used > > when SDA is stuck low. So, I do wonder if we should apply the recovery > > after a timeout. Stuck SDA might be one reason for timeout, but there > > may be others... >=20 > This is ancient code. And regarding your question - > Might be it would be reasonable to add call of > i2c_davinci_wait_bus_not_busy() at the end of i2c_davinci_xfer()? > This way we will wait for Bus Free before performing recovery. That might be an improvement, but the generic question still remains: Is a timeout a reason for recovery? SDA stuck low is one reason for a timeout. I have problems making up my mind here between being pragmatic and being in accordance with the specs. > Of course, i2c_davinci_wait_bus_not_busy() has to be fixed first > as proposed by Alexander Sverdlin here: > https://patchwork.ozlabs.org/patch/448994/.=20 Okay, good that you said it. So I'll give his patch series priority over this one. --nFBW6CQlri5Qm8JQ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJVHvWmAAoJEBQN5MwUoCm2E9AQAJxNNrXZF8jlfD8QCiNZgzi1 YKuTRXhkWcUaAokU+Am9+DqUL7BTRnRZjNaqMFVVPo6xx6aSN9pvi9XTD3TGQIXW wHT+AGLSSMWUUVeOsPyHYEVHxienQ5Aen869HSs0jg79YbFJ7+g+MiF4Gn3XG+Qo Ay6clqsuCU4T8jUMEzWOJJMkGlX1foo0/Iw+7iZJwj1LEF/vWkGriAWR7F2pKMFY yZY2AS++wXKP5dxEOHRDg3QOzhB/hK7cMwk0fJICa+35sLSVZig7WoZ7KhW8lueJ KLXEUIegGySyBrzh60u8u2EVFx7gl89Go4jDb4kq5vYtxujw7qNrz2zOYHKBR9sg q9afej8EYC8Ls1ejMIqoIiqrGgtoK1SkK5VPwcVXG8SpnQYkswrxwJrISKWtGJoZ mUTcw9bSTDhVyDgMN9BRJH9wass+OG2RzcY+g2xDrT0kdHdjIOTZFRcqMW9TS6tb lHEYzif8U/VYaDpATLU3jLIVLks1tWSpUAfjtLVh6ONNIgfktxmCTE3FAw1q1pCr KCzY3iBikCCIw+SnmYffbrujSmAqUOl4LhV2KRmYZNcWe+jl85vHlBYtZ4krORf9 22+AhZI7DfZRQXp85s8tOU995oqAWQqM7e/2g+W5ZkZDSnCB/31GFll0vhDrNhZB EyfHlrAPaZEZBT2ZZESY =x/Bq -----END PGP SIGNATURE----- --nFBW6CQlri5Qm8JQ--