w1: w1_therm: fixes w1_seq for ds28ea00 sensors

BugLink: https://bugs.launchpad.net/bugs/1971497
[ 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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c
index e028e00927991cd6aa1e91dcca6ce7fb9d5b79a1..cf1e01f0dede32c52fe0902c0bf2b93b6d89f42a 100644 (file)
--- 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 */