[PATCH 3.16 08/26] i2c: rk3x: fix 0 length write transfers

From: Greg Kroah-Hartman
Date: Tue Oct 07 2014 - 19:41:53 EST


3.16-stable review patch. If anyone has any objections, please let me know.

------------------

From: Alexandru M Stan <amstan@xxxxxxxxxxxx>

commit cf27020d2f253bac6457d6833b97141030f0122a upstream.

i2cdetect -q was broken (everything was a false positive, and no transfers were
actually being sent over i2c). The way it works is by sending a 0 length write
request and checking for NACK. This patch fixes the 0 length writes and actually
sends them.

Reported-by: Doug Anderson <dianders@xxxxxxxxxxxx>
Signed-off-by: Alexandru M Stan <amstan@xxxxxxxxxxxx>
Tested-by: Doug Anderson <dianders@xxxxxxxxxxxx>
Tested-by: Max Schwarz <max.schwarz@xxxxxxxxx>
Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/i2c/busses/i2c-rk3x.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/i2c/busses/i2c-rk3x.c
+++ b/drivers/i2c/busses/i2c-rk3x.c
@@ -238,7 +238,7 @@ static void rk3x_i2c_fill_transmit_buf(s
for (i = 0; i < 8; ++i) {
val = 0;
for (j = 0; j < 4; ++j) {
- if (i2c->processed == i2c->msg->len)
+ if ((i2c->processed == i2c->msg->len) && (cnt != 0))
break;

if (i2c->processed == 0 && cnt == 0)


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