[PATCH 4.9 182/218] w1: w1_therm: fixes w1_seq for ds28ea00 sensors

Greg Kroah-Hartman
2022-04-18T14:23:22Z

From: Lucas Denefle <lucas.denefle@converge.io>

[ Upstream commit 41a92a89eee819298f805c40187ad8b02bb53426 ]

w1_seq was failing due to several devices responding to the
CHAIN_DONE at the same time. Now properly selects the current
device in the chain with MATCH_ROM. Also acknowledgment was
read twice.

Signed-off-by: Lucas Denefle <lucas.denefle@converge.io>
Link: https://lore.kernel.org/r/20220223113558.232750-1-lucas.denefle@converge.io
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/w1/slaves/w1_therm.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c
index 82611f197b0a..7d0e09867bc7 100644
--- a/drivers/w1/slaves/w1_therm.c
+++ b/drivers/w1/slaves/w1_therm.c
@@ -589,16 +589,20 @@ static ssize_t w1_seq_show(struct device *device,
if (sl->reg_num.id == reg_num->id)
seq = i;

+ if (w1_reset_bus(sl->master))
+ goto error;
+
+ /* Put the device into chain DONE state */
+ w1_write_8(sl->master, W1_MATCH_ROM);
+ w1_write_block(sl->master, (u8 *)&rn, 8);
w1_write_8(sl->master, W1_42_CHAIN);
w1_write_8(sl->master, W1_42_CHAIN_DONE);
w1_write_8(sl->master, W1_42_CHAIN_DONE_INV);
- w1_read_block(sl->master, &ack, sizeof(ack));

/* check for acknowledgment */
ack = w1_read_8(sl->master);
if (ack != W1_42_SUCCESS_CONFIRM_BYTE)
goto error;
-
}

/* Exit from CHAIN state */
--
2.35.1