From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yoshihiro Kaneko Date: Sun, 15 Feb 2015 14:43:15 +0000 Subject: [PATCH/RFC] i2c: rcar: Fix order of restart and clear status Message-Id: <1424011396-3492-1-git-send-email-ykaneko0929@gmail.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-i2c@vger.kernel.org Cc: Wolfram Sang , Simon Horman , Magnus Damm , linux-sh@vger.kernel.org From: Ryo Kataoka In case of repeated START condition, the restart has to be kicked before clear status (MSR register). If it is kicked after clear status, R-Car I2C may transfer data (TXD register) or receive data (RXD register) instead of transferring slave address (MAR register). Signed-off-by: Ryo Kataoka Signed-off-by: Yoshihiro Kaneko --- This patch is based on i2c/for-next branch of Wolfram Sang's linux tree. drivers/i2c/busses/i2c-rcar.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c index 71a6e07..96c349f 100644 --- a/drivers/i2c/busses/i2c-rcar.c +++ b/drivers/i2c/busses/i2c-rcar.c @@ -2,6 +2,7 @@ * Driver for the Renesas RCar I2C unit * * Copyright (C) 2014 Wolfram Sang + * Copyright (C) 2013-2014 Renesas Electronics Corporation * * Copyright (C) 2012-14 Renesas Solutions Corp. * Kuninori Morimoto @@ -99,6 +100,7 @@ #define ID_DONE (1 << 2) #define ID_ARBLOST (1 << 3) #define ID_NACK (1 << 4) +#define ID_FIRST_MSG (1 << 5) enum rcar_i2c_type { I2C_RCAR_GEN1, @@ -125,6 +127,7 @@ struct rcar_i2c_priv { #define rcar_i2c_is_recv(p) ((p)->msg->flags & I2C_M_RD) #define rcar_i2c_flags_set(p, f) ((p)->flags |= (f)) +#define rcar_i2c_flags_clr(p, f) ((p)->flags &= ~(f)) #define rcar_i2c_flags_has(p, f) ((p)->flags & (f)) #define LOOP_TIMEOUT 1024 @@ -257,8 +260,14 @@ static void rcar_i2c_prepare_msg(struct rcar_i2c_priv *priv) int read = !!rcar_i2c_is_recv(priv); rcar_i2c_write(priv, ICMAR, (priv->msg->addr << 1) | read); - rcar_i2c_write(priv, ICMSR, 0); - rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_START); + if (rcar_i2c_flags_has(priv, ID_FIRST_MSG)) { /* start */ + rcar_i2c_write(priv, ICMSR, 0); + rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_START); + rcar_i2c_flags_clr(priv, ID_FIRST_MSG); + } else { /* restart */ + rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_START); + rcar_i2c_write(priv, ICMSR, 0); + } rcar_i2c_write(priv, ICMIER, read ? RCAR_IRQ_RECV : RCAR_IRQ_SEND); } @@ -524,6 +533,8 @@ static int rcar_i2c_master_xfer(struct i2c_adapter *adap, priv->msg = &msgs[i]; priv->pos = 0; priv->flags = 0; + if (i = 0) + rcar_i2c_flags_set(priv, ID_FIRST_MSG); if (i = num - 1) rcar_i2c_flags_set(priv, ID_LAST_MSG); -- 1.9.1