Re: [RFC PATCH v2 6/7] typec: tcpm: Represent source supply through power_supply class

[Hans de Goede]

Hi,

On 11/24/2017 01:19 PM, Heikki Krogerus wrote:
> Hi,
>
> On Tue, Nov 14, 2017 at 11:44:47AM +0000, Adam Thomson wrote:
> > diff --git a/drivers/usb/typec/tcpm.c b/drivers/usb/typec/tcpm.c
> > index 78983e1..7c26c3d 100644
> > --- a/drivers/usb/typec/tcpm.c
> > +++ b/drivers/usb/typec/tcpm.c
> > @@ -12,6 +12,7 @@
> >   #include <linux/kernel.h>
> >   #include <linux/module.h>
> >   #include <linux/mutex.h>
> > +#include <linux/power_supply.h>
> >   #include <linux/proc_fs.h>
> >   #include <linux/sched/clock.h>
> >   #include <linux/seq_file.h>
> > @@ -277,6 +278,10 @@ struct tcpm_port {
> >   	u32 current_limit;
> >   	u32 supply_voltage;
> >   
> > +	/* Used to export TA voltage and current */
> > +	struct power_supply *psy;
> > +	struct power_supply_desc psy_desc;
> > +
> >   	u32 bist_request;
> >   
> >   	/* PD state for Vendor Defined Messages */
> > @@ -1756,6 +1761,7 @@ static int tcpm_pd_select_pdo(struct tcpm_port *port)
> >   	int ret = -EINVAL;
> >   
> >   	port->pps_data.supported = false;
> > +	port->psy_desc.type = POWER_SUPPLY_TYPE_USB_PD;
> >   
> >   	/*
> >   	 * Select the source PDO providing the most power while staying within
> > @@ -1775,8 +1781,10 @@ static int tcpm_pd_select_pdo(struct tcpm_port *port)
> >   			mv = pdo_min_voltage(pdo);
> >   			break;
> >   		case PDO_TYPE_APDO:
> > -			if (pdo_apdo_type(pdo) == APDO_TYPE_PPS)
> > +			if (pdo_apdo_type(pdo) == APDO_TYPE_PPS) {
> >   				port->pps_data.supported = true;
> > +				port->psy_desc.type = POWER_SUPPLY_TYPE_USB_PD_PPS;
> > +			}
> >   			continue;
> >   		default:
> >   			tcpm_log(port, "Invalid PDO type, ignoring");
> > @@ -2248,6 +2256,9 @@ static void tcpm_reset_port(struct tcpm_port *port)
> >   	port->try_snk_count = 0;
> >   	port->supply_voltage = 0;
> >   	port->current_limit = 0;
> > +	port->psy_desc.type = POWER_SUPPLY_TYPE_USB_TYPE_C;
>
> Is it OK to everybody that the type of the psy is changed like that?
> Hans?!
>
> We do have drivers that already change the type, for example
> drivers/power/supply/isp1704_charger.c, but what does the user space
> expect? The ABI for the power supply class was never documented I
> guess.

The main userspace consumer of the power_supply sysfs class is upower,
upower knows about 3 types: "Mains", "Battery" and "USB", anything
else it gives a type of UP_DEVICE_KIND_UNKNOWN. So POWER_SUPPLY_TYPE_USB_TYPE_C
vs POWER_SUPPLY_TYPE_USB_PD_PPS does matter to it.

Regards,

Hans