From mboxrd@z Thu Jan 1 00:00:00 1970 From: Esben Haabendal Subject: [PATCH v2] i2c-mpc: generate START condition after STOP caused by read i2c_msg Date: Tue, 19 May 2009 07:22:10 +0200 Message-ID: <4A124202.4010201@doredevelopment.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linuxppc-dev-mnsaURCQ41sdnm+yROfE0A@public.gmane.org List-Id: linux-i2c@vger.kernel.org This fixes MAL (arbitration lost) bug caused by illegal use of RSTA (repeated START) after STOP condition generated after last byte of reads. With this patch, it is possible to do an i2c_transfer() with additional i2c_msg's following the I2C_M_RD messages. It still needs to be resolved if it is possible to fix this issue by removing the STOP condition after reads in a robust way. Signed-off-by: Esben Haabendal --- drivers/i2c/busses/i2c-mpc.c | 9 +++++++-- 1 files changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c index 4af5c09..0199f9a 100644 --- a/drivers/i2c/busses/i2c-mpc.c +++ b/drivers/i2c/busses/i2c-mpc.c @@ -456,17 +456,22 @@ static int mpc_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) } for (i = 0; ret >= 0 && i < num; i++) { + int restart = i; pmsg = &msgs[i]; dev_dbg(i2c->dev, "Doing %s %d bytes to 0x%02x - %d of %d messages\n", pmsg->flags & I2C_M_RD ? "read" : "write", pmsg->len, pmsg->addr, i + 1, num); + if (i > 0 && ((pmsg - 1)->flags & I2C_M_RD)) + restart = 0; if (pmsg->flags & I2C_M_RD) ret = - mpc_read(i2c, pmsg->addr, pmsg->buf, pmsg->len, i); + mpc_read(i2c, pmsg->addr, pmsg->buf, pmsg->len, + restart); else ret = - mpc_write(i2c, pmsg->addr, pmsg->buf, pmsg->len, i); + mpc_write(i2c, pmsg->addr, pmsg->buf, pmsg->len, + restart); } mpc_i2c_stop(i2c); return (ret < 0) ? ret : num; -- 1.6.3.1