From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: Re: [PATCH] i2c: omap: fix bus recovery setup Date: Tue, 14 Jul 2015 13:10:05 +0200 Message-ID: <20150714111004.GB1517@katana> References: <1436366127-24756-1-git-send-email-jlu@pengutronix.de> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="A6N2fC+uXW/VQSAv" Return-path: Content-Disposition: inline In-Reply-To: <1436366127-24756-1-git-send-email-jlu-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jan Luebbe Cc: Tony Lindgren , Felipe Balbi , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, kernel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org List-Id: linux-i2c@vger.kernel.org --A6N2fC+uXW/VQSAv Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jul 08, 2015 at 04:35:27PM +0200, Jan Luebbe wrote: > At least on the AM335x, enabling OMAP_I2C_SYSTEST_ST_EN is not enough to Felipe: it seems you did not need this; is this AM335x specific? > allow direct access to the SCL and SDA pins. In addition to ST_EN, we > need to set the TMODE to 0b11 (Loop back & SDA/SCL IO mode select). > Also, as the reset values of SCL_O and SDA_O are 0 (which means "drive > low level"), we need to set them to 1 (which means "high-impedance") to > avoid unwanted changes on the pins. >=20 > As a precaution, reset all these bits to their default values after > recovery is complete. >=20 > Signed-off-by: Jan Luebbe > --- > drivers/i2c/busses/i2c-omap.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) >=20 > diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c > index d1c22e3fdd14..fc9bf7f30e35 100644 > --- a/drivers/i2c/busses/i2c-omap.c > +++ b/drivers/i2c/busses/i2c-omap.c > @@ -1247,7 +1247,14 @@ static void omap_i2c_prepare_recovery(struct i2c_a= dapter *adap) > u32 reg; > =20 > reg =3D omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG); > + /* enable test mode */ > reg |=3D OMAP_I2C_SYSTEST_ST_EN; > + /* select SDA/SCL IO mode */ > + reg |=3D 3 << OMAP_I2C_SYSTEST_TMODE_SHIFT; > + /* set SCL to high-impedance state (reset value is 0) */ > + reg |=3D OMAP_I2C_SYSTEST_SCL_O; > + /* set SDA to high-impedance state (reset value is 0) */ > + reg |=3D OMAP_I2C_SYSTEST_SDA_O; > omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, reg); > } > =20 > @@ -1257,7 +1264,11 @@ static void omap_i2c_unprepare_recovery(struct i2c= _adapter *adap) > u32 reg; > =20 > reg =3D omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG); > + /* restore reset values */ > reg &=3D ~OMAP_I2C_SYSTEST_ST_EN; > + reg &=3D ~OMAP_I2C_SYSTEST_TMODE_MASK; > + reg &=3D ~OMAP_I2C_SYSTEST_SCL_O; > + reg &=3D ~OMAP_I2C_SYSTEST_SDA_O; > omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, reg); > } > =20 > --=20 > 2.1.4 >=20 --A6N2fC+uXW/VQSAv Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJVpO4MAAoJEBQN5MwUoCm2UioP+wR7mlSAYqA1KhLA0NvJCLl/ lg0p8M3CahfjkI64nqzcZpLSYWOsZxtpoaJ1txRVHEjlFwvUh/uX3f1z5aEilLia Xx2j6jRo+BlKZ6QUYM1biA7f8GAIRF1sUm0UD5lCSIQjaF78uLrVSp/xLU8/8Cnd ocahJ/kNRetThRzx3N2Q7zFPtFw6gbu9etmFcwZtVd50mOeyHtG1PT8HP/baTc8/ uopN6BlQmvMJUA06SfNXtS890r4Hcu8hVwPouZ1+6MbBYCc3Bqa0hlAwpsz2cH6w ebwa8In67f7bNhlxPtFAgv9B4oTBzbb88eSiw6wWxe53/qPLTRXaoO7CkJNwze1+ krWIqMoqHU1VmxvohxrnSKOloFb7EzWmXexnrzWbh0FPqjThc41yHSsayEW9icBW 2S5BaBSaZ1zcKieezlqJAtXczNdTXIUG/UC2jMq98ApsS/8vHTopSXdegO0pqnA4 vij6LPSYDT2yFX6I3um+b38xU7DRCrCG6OtFRVE+nLG1IplUHuGMQ4R4vx6HRabj 2i+xl+UhTsfc7Z9YcHafPLZqgAUq/6x0mGKZRykjygypJdHq4QkYzVd73uuYiax8 /O8HTXZEmKp8Uj1xv4Yxa7BdDUQLSIBGwFhLHjYVsdEinMwK6erZGmLh/it8YeCB /2vQhkxnIHzbFhJ/wOsa =7oIj -----END PGP SIGNATURE----- --A6N2fC+uXW/VQSAv--