Re: [PATCH] i2c-mpc: generate START condition after STOP caused by read i2c_msg
From: Wolfram Sang <hidden>
Date: 2009-05-14 08:35:02
Also in:
linux-i2c
On Thu, May 14, 2009 at 10:10:03AM +0200, Esben Haabendal wrote:
This fixes MAL (arbitration lost) bug caused by illegal use of RSTA (repeated START) after STOP condition generated after last byte of reads.
Could you elaborate a bit, please? Like an example when the original bug occured (so I could reproduce easily) and how this patch actually solves the problem.
quoted hunk ↗ jump to hunk
Signed-off-by: Esben Haabendal <redacted> --- 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..9fe05d9 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))
CodingStyle: Spaces around '-'
+ 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; -- 1.6.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
-- Pengutronix e.K. | Wolfram Sang | Industrial Linux Solutions | http://www.pengutronix.de/ |
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