6.6-stable review patch. If anyone has any objections, please let me know.
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From: Zev Weiss zev@bewilderbeest.net
commit 920057ad521dc8669e534736c2a12c14ec9fb2d7 upstream.
In the regmap conversion in commit 4ef2774511dc ("hwmon: (nct6775) Convert register access to regmap API") I reused the 'reg' variable for all three register reads in the fan speed calculation loop in nct6775_update_device(), but failed to notice that the value from the first one (data->REG_FAN[i]) is actually used in the call to nct6775_select_fan_div() at the end of the loop body. Since that patch the register value passed to nct6775_select_fan_div() has been (conditionally) incorrectly clobbered with the value of a different register than intended, which has in at least some cases resulted in fan speeds being adjusted down to zero.
Fix this by using dedicated temporaries for the two intermediate register reads instead of 'reg'.
Signed-off-by: Zev Weiss zev@bewilderbeest.net Fixes: 4ef2774511dc ("hwmon: (nct6775) Convert register access to regmap API") Reported-by: Thomas Zajic zlatko@gmx.at Tested-by: Thomas Zajic zlatko@gmx.at Cc: stable@vger.kernel.org # v5.19+ Link: https://lore.kernel.org/r/20230929200822.964-2-zev@bewilderbeest.net Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/hwmon/nct6775-core.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)
--- a/drivers/hwmon/nct6775-core.c +++ b/drivers/hwmon/nct6775-core.c @@ -1614,17 +1614,21 @@ struct nct6775_data *nct6775_update_devi data->fan_div[i]);
if (data->has_fan_min & BIT(i)) { - err = nct6775_read_value(data, data->REG_FAN_MIN[i], ®); + u16 tmp; + + err = nct6775_read_value(data, data->REG_FAN_MIN[i], &tmp); if (err) goto out; - data->fan_min[i] = reg; + data->fan_min[i] = tmp; }
if (data->REG_FAN_PULSES[i]) { - err = nct6775_read_value(data, data->REG_FAN_PULSES[i], ®); + u16 tmp; + + err = nct6775_read_value(data, data->REG_FAN_PULSES[i], &tmp); if (err) goto out; - data->fan_pulses[i] = (reg >> data->FAN_PULSE_SHIFT[i]) & 0x03; + data->fan_pulses[i] = (tmp >> data->FAN_PULSE_SHIFT[i]) & 0x03; }
err = nct6775_select_fan_div(dev, data, i, reg);