[PATCH 5.4 409/475] w1: w1_therm: fixes w1_seq for ds28ea00 sensors

[Greg Kroah-Hartman]

From: Lucas Denefle <lucas.denefle@xxxxxxxxxxx>

[ 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@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220223113558.232750-1-lucas.denefle@xxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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 e028e0092799..cf1e01f0dede 100644
--- a/drivers/w1/slaves/w1_therm.c
+++ b/drivers/w1/slaves/w1_therm.c
@@ -679,16 +679,20 @@ 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