linux-kernel - Re: [PATCH v2 6/7] platform/chrome: cros_ec

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Message-ID: <CANFp7mVjSjj5fWBqTc8CTNdHatBN4s-0zj7uhgpo5raOiQN2RA@mail.gmail.com>
Date: Thu, 31 Oct 2024 15:23:27 -0700
From: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: heikki.krogerus@...ux.intel.com, tzungbi@...nel.org, 
	linux-usb@...r.kernel.org, chrome-platform@...ts.linux.dev, jthies@...gle.com, 
	akuchynski@...gle.com, pmalani@...omium.org, 
	Benson Leung <bleung@...omium.org>, Guenter Roeck <groeck@...omium.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 6/7] platform/chrome: cros_ec_typec: Thunderbolt support

On Thu, Oct 31, 2024 at 11:51 AM Dmitry Baryshkov
<dmitry.baryshkov@...aro.org> wrote:
>
> On Wed, Oct 30, 2024 at 02:28:37PM -0700, Abhishek Pandit-Subedi wrote:
> > Add support for entering and exiting Thunderbolt alt-mode using AP
> > driven alt-mode.
> >
> > Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
> > ---
> >
> > Changes in v2:
> > - Refactored thunderbolt support into cros_typec_altmode.c
> >
> >  drivers/platform/chrome/cros_ec_typec.c      | 29 ++++---
> >  drivers/platform/chrome/cros_typec_altmode.c | 85 ++++++++++++++++++++
> >  drivers/platform/chrome/cros_typec_altmode.h | 14 ++++
> >  3 files changed, 116 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
> > index 7997e7136c4c..3e043b1c1cc8 100644
> > --- a/drivers/platform/chrome/cros_ec_typec.c
> > +++ b/drivers/platform/chrome/cros_ec_typec.c
> > @@ -304,21 +304,26 @@ static int cros_typec_register_port_altmodes(struct cros_typec_data *typec,
> >       typec_altmode_set_drvdata(amode, port);
> >       amode->ops = &port_amode_ops;
> >  #endif
> > -
> >       /*
> >        * Register TBT compatibility alt mode. The EC will not enter the mode
> > -      * if it doesn't support it, so it's safe to register it unconditionally
> > -      * here for now.
> > +      * if it doesn't support it and it will not enter automatically by
> > +      * design so we can use the |ap_driven_altmode| feature to check if we
> > +      * should register it.
> >        */
> > -     memset(&desc, 0, sizeof(desc));
> > -     desc.svid = USB_TYPEC_TBT_SID;
> > -     desc.mode = TYPEC_ANY_MODE;
> > -     amode = typec_port_register_altmode(port->port, &desc);
> > -     if (IS_ERR(amode))
> > -             return PTR_ERR(amode);
> > -     port->port_altmode[CROS_EC_ALTMODE_TBT] = amode;
> > -     typec_altmode_set_drvdata(amode, port);
> > -     amode->ops = &port_amode_ops;
> > +     if (typec->ap_driven_altmode) {
> > +             memset(&desc, 0, sizeof(desc));
> > +             desc.svid = USB_TYPEC_TBT_SID;
> > +             desc.mode = TYPEC_ANY_MODE;
> > +             amode = cros_typec_register_thunderbolt(port, &desc);
> > +             if (IS_ERR(amode))
> > +                     return PTR_ERR(amode);
> > +             port->port_altmode[CROS_EC_ALTMODE_TBT] = amode;
> > +
> > +#if !IS_ENABLED(CONFIG_TYPEC_TBT_ALTMODE)
> > +             typec_altmode_set_drvdata(amode, port);
> > +             amode->ops = &port_amode_ops;
> > +#endif
>
> Why? Usually having the code block under an #if is a frowned upon
> practice.

There are some CrosEC implementations that provide full VDM access for
mode entry and this code was previously added to support that. I'm
looking into whether this was fully deployed -- if not, I will remove
this #if block entirely in my next patch series.

Will do the same for displayport above.

>
> > +     }
> >
> >       port->state.alt = NULL;
> >       port->state.mode = TYPEC_STATE_USB;
>
> [...]
>
> > diff --git a/drivers/platform/chrome/cros_typec_altmode.h b/drivers/platform/chrome/cros_typec_altmode.h
> > index c6f8fb02c99c..c71568314e3f 100644
> > --- a/drivers/platform/chrome/cros_typec_altmode.h
> > +++ b/drivers/platform/chrome/cros_typec_altmode.h
> > @@ -31,4 +31,18 @@ static inline int cros_typec_displayport_status_update(struct typec_altmode *alt
> >       return 0;
> >  }
> >  #endif
> > +
> > +#if IS_ENABLED(CONFIG_TYPEC_TBT_ALTMODE)
> > +struct typec_altmode *
> > +cros_typec_register_thunderbolt(struct cros_typec_port *port,
> > +                             struct typec_altmode_desc *desc);
> > +#else
> > +struct typec_altmode *
>
> static inline struct ...
> LGTM otherwise

I ran allmodconfig and x86_64_defconfig but forgot to run allmodconfig
- these features :( -- argh... I'll add this to my testing steps.

>
> > +cros_typec_register_thunderbolt(struct cros_typec_port *port,
> > +                             struct typec_altmode_desc *desc)
> > +{
> > +     return typec_port_register_altmode(port->port, desc);
> > +}
> > +#endif
> > +
> >  #endif /* __CROS_TYPEC_ALTMODE_H__ */
> > --
> > 2.47.0.163.g1226f6d8fa-goog
> >
>
> --
> With best wishes
> Dmitry