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SubjectRe: [PATCH v2] usb: typec: tcpm: Report back negotiated PPS voltage and current
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On 10/08/2018 05:53 AM, Adam Thomson wrote:
> Currently when requesting a specific voltage or current through
> the psy interface, for PPS, when reading back from that interface
> the values will always be the same as previously given, if the
> request was successful. However PPS only allows for 20mV voltage
> steps and 50mA current steps, and the psy class expects microvolt
> and micro amp requests, so inbetween values can be provided through
> this interface. Really when reading back the true values negotiated
> should be given, and not the ones originally asked for.
>
> To report the actual values negotiated with the Source, the values
> stored are now rounded down to the relevant step units prior to
> building the PPS request, so that those values are later correctly
> reported through the psy interface. In addition this improves the
> adjustments made to meet the operating power requirements of the
> platform, which previously could have been slightly out due to not
> using valid PPS units of voltage and current.
>
> Signed-off-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>

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

> ---
> Changes are based on usb-testing (e7a2c3fa2857)
>
> Changes in v2:
> - Rounding down of PPS voltage and current values moved to relevant API
> functions so stored values are correctly updated prior to all subsequent
> usage and decision making, as discuessed with Guenter.
>
> drivers/usb/typec/tcpm/tcpm.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index b06eac8..dbbd71f 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -4113,6 +4113,9 @@ static int tcpm_pps_set_op_curr(struct tcpm_port *port, u16 op_curr)
> goto port_unlock;
> }
>
> + /* Round down operating current to align with PPS valid steps */
> + op_curr = op_curr - (op_curr % RDO_PROG_CURR_MA_STEP);
> +
> reinit_completion(&port->pps_complete);
> port->pps_data.op_curr = op_curr;
> port->pps_status = 0;
> @@ -4166,6 +4169,9 @@ static int tcpm_pps_set_out_volt(struct tcpm_port *port, u16 out_volt)
> goto port_unlock;
> }
>
> + /* Round down output voltage to align with PPS valid steps */
> + out_volt = out_volt - (out_volt % RDO_PROG_VOLT_MV_STEP);
> +
> reinit_completion(&port->pps_complete);
> port->pps_data.out_volt = out_volt;
> port->pps_status = 0;
>

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