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usb: typec: tcpm: Correct the PPS out_volt calculation 

When Sink negotiates PPS, the voltage range of selected PPS APDO might
not cover the previous voltage (out_volt). If the previous out_volt is
lower than the new min_volt, the output voltage in RDO might be set to
an invalid value. For instance, supposed that the previous voltage is
5V, and the new voltage range in the APDO is 7V-12V. Then the output
voltage in the RDO should not be set to 5V which is lower than the
possible min_volt 7V.

Fix this by choosing the maximal value between the previous voltage and
the new min_volt first. And ensure that this value will not exceed the
new max_volt. The new out_volt will fall within the new voltage range
while being the closest value compared to the previous out_volt.

Signed-off-by: Kyle Tso <kyletso@google.com>
Reviewed-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Fixes: c710d0bb76 ("usb: typec: tcpm: Extend the matching rules on PPS APDO selection")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Kyle Tso 2019-01-30 11:13:53 +08:00 committed by Greg Kroah-Hartman
parent c7b0c3bbe4
commit a07ddce4df
1 changed files with 2 additions and 1 deletions
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3
drivers/usb/typec/tcpm/tcpm.c
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@ -2297,7 +2297,8 @@ static unsigned int tcpm_pd_select_pps_apdo(struct tcpm_port *port)
pdo_pps_apdo_max_voltage(snk));
port->pps_data.max_curr = min_pps_apdo_current(src, snk);
port->pps_data.out_volt = min(port->pps_data.max_volt,
port->pps_data.out_volt);
max(port->pps_data.min_volt,
port->pps_data.out_volt));
port->pps_data.op_curr = min(port->pps_data.max_curr,
port->pps_data.op_curr);
}