[PATCH 4.9 5/9] hwmon: (it87) Avoid registering the same chip on both SIO addresses

Greg Kroah-Hartman
2017-05-06T20:40:52Z

From: Guenter Roeck <linux@roeck-us.net>

commit 8358378b22518d92424597503d3c1cd302a490b6 upstream.

IT8705F is known to respond on both SIO addresses. Registering it twice
may result in system lockups.

Reported-by: Russell King <linux@armlinux.org.uk>
Fixes: e84bd9535e2b ("hwmon: (it87) Add support for second Super-IO chip")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Cc: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/hwmon/it87.c | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)

--- a/drivers/hwmon/it87.c
+++ b/drivers/hwmon/it87.c
@@ -3115,7 +3115,7 @@ static int __init sm_it87_init(void)
{
int sioaddr[2] = { REG_2E, REG_4E };
struct it87_sio_data sio_data;
- unsigned short isa_address;
+ unsigned short isa_address[2];
bool found = false;
int i, err;

@@ -3125,15 +3125,29 @@ static int __init sm_it87_init(void)

for (i = 0; i < ARRAY_SIZE(sioaddr); i++) {
memset(&sio_data, 0, sizeof(struct it87_sio_data));
- isa_address = 0;
- err = it87_find(sioaddr[i], &isa_address, &sio_data);
- if (err || isa_address == 0)
+ isa_address[i] = 0;
+ err = it87_find(sioaddr[i], &isa_address[i], &sio_data);
+ if (err || isa_address[i] == 0)
continue;
+ /*
+ * Don't register second chip if its ISA address matches
+ * the first chip's ISA address.
+ */
+ if (i && isa_address[i] == isa_address[0])
+ break;

- err = it87_device_add(i, isa_address, &sio_data);
+ err = it87_device_add(i, isa_address[i], &sio_data);
if (err)
goto exit_dev_unregister;
+
found = true;
+
+ /*
+ * IT8705F may respond on both SIO addresses.
+ * Stop probing after finding one.
+ */
+ if (sio_data.type == it87)
+ break;
}

if (!found) {