linux-kernel - RE: [PATCH 2/4] usb: typec: hd3ss3220: use typec_get_fw_cap() to fill typec

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Message-ID:
 <ZR1P278MB10226D24060AEAB29E3E7E2C9F5D2@ZR1P278MB1022.CHEP278.PROD.OUTLOOK.COM>
Date: Fri, 8 Nov 2024 10:29:00 +0000
From: Facklam, Olivér <oliver.facklam@...hlke.com>
To: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "von Heyl,
 Benedict" <benedict.vonheyl@...hlke.com>, Först, Mathis
	<mathis.foerst@...hlke.com>, "Glettig, Michael" <Michael.Glettig@...hlke.com>
Subject: RE: [PATCH 2/4] usb: typec: hd3ss3220: use typec_get_fw_cap() to fill
 typec_cap

Hello Heikki,

> -----Original Message-----
> From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> Sent: Friday, November 8, 2024 9:08 AM
> To: Facklam, Olivér <oliver.facklam@...hlke.com>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>; linux-
> usb@...r.kernel.org; linux-kernel@...r.kernel.org; von Heyl, Benedict
> <benedict.vonheyl@...hlke.com>; Först, Mathis
> <mathis.foerst@...hlke.com>; Glettig, Michael
> <Michael.Glettig@...hlke.com>
> Subject: Re: [PATCH 2/4] usb: typec: hd3ss3220: use typec_get_fw_cap() to fill
> typec_cap
> 
> On Thu, Nov 07, 2024 at 03:24:44PM +0000, Facklam, Olivér wrote:
> > Hello Heikki,
> >
> > > -----Original Message-----
> > > From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> > > Sent: Thursday, November 7, 2024 3:21 PM
> > > To: Facklam, Olivér <oliver.facklam@...hlke.com>
> > > Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>; linux-
> > > usb@...r.kernel.org; linux-kernel@...r.kernel.org; von Heyl,
> > > Benedict <benedict.vonheyl@...hlke.com>; Först, Mathis
> > > <mathis.foerst@...hlke.com>; Glettig, Michael
> > > <Michael.Glettig@...hlke.com>
> > > Subject: Re: [PATCH 2/4] usb: typec: hd3ss3220: use
> > > typec_get_fw_cap() to fill typec_cap
> > >
> > > Hi Oliver,
> > >
> > > On Thu, Nov 07, 2024 at 12:43:28PM +0100, Oliver Facklam via B4
> > > Relay
> > > wrote:
> > > > From: Oliver Facklam <oliver.facklam@...hlke.com>
> > > >
> > > > The type, data, and prefer_role properties were previously
> > > > hard-coded when creating the struct typec_capability.
> > > >
> > > > Use typec_get_fw_cap() to populate these fields based on the
> > > > respective fwnode properties.
> > > >
> > > > Signed-off-by: Oliver Facklam <oliver.facklam@...hlke.com>
> > > > ---
> > > >  drivers/usb/typec/hd3ss3220.c | 8 ++++----
> > > >  1 file changed, 4 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/drivers/usb/typec/hd3ss3220.c
> > > > b/drivers/usb/typec/hd3ss3220.c index
> > > >
> > >
> 56f74bf70895ca701083bde44a5bbe0b691551e1..e6e4b1871b5d805f8c3671
> > > 31509f
> > > > 4e6ec0d2b5f0 100644
> > > > --- a/drivers/usb/typec/hd3ss3220.c
> > > > +++ b/drivers/usb/typec/hd3ss3220.c
> > > > @@ -259,12 +259,12 @@ static int hd3ss3220_probe(struct i2c_client
> > > *client)
> > > >  		goto err_put_fwnode;
> > > >  	}
> > > >
> > > > -	typec_cap.prefer_role = TYPEC_NO_PREFERRED_ROLE;
> > > > +	ret = typec_get_fw_cap(&typec_cap, connector);
> > > > +	if (ret)
> > > > +		goto err_put_role;
> > >
> > > You are not leaving any fallback here. Are you sure all the existing
> > > systems supply those properties?
> > >
> > > There is another problem. At least "data-role" property is optional,
> > > but that will in practice make it a requirement.
> >
> > I missed that typec_get_fw_cap() was not setting a default if the property is
> absent.
> >
> > >
> > > I think it would be safer to use the values from the device
> > > properties only if they are available. Otherwise simply use default values.
> >
> > I'll add back the previous values as defaults before calling
> typec_get_fw_cap().
> > That will make data-role and try-power-role optional again, as intended.
> >
> > However, "power-role" seems to be required by the function. Is this
> expected?
> 
> Yes.
> 
> > Or should I write my own fwnode parsing logic?
> 
> No, don't do that.
> 
> You can check the return value. If it's -EINVAL or -ENXIO, the properties are
> not there, and you can safely use the defaults.
> Otherwise, consider the failure as critical.

Thanks for the hint, will do.

> 
> thanks,
> 
> --
> heikki