Re: [PATCH v1 2/4] usb: typec: Add attribute file showing the USB Modes of the partner

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

On Sun, Oct 06, 2024 at 07:22:42PM +0300, Dmitry Baryshkov wrote:
> On Fri, Oct 04, 2024 at 05:04:37PM GMT, Heikki Krogerus wrote:
> > This attribute file shows the supported USB modes (USB 2.0,
> > USB 3.0 and USB4) of the partner, and the currently active
> > mode.
> > 
> > The active mode is determined primarily by checking the
> > speed of the enumerated USB device. When USB Power Delivery
> > is supported, the active USB mode should be always the mode
> > that was used with the Enter_USB Message, regardless of the
> > result of the USB enumeration. The port drivers can
> > separately assign the mode with a dedicated API.
> > 
> > If USB Power Delivery Identity is supplied for the partner
> > device, the supported modes are extracted from it.
> > 
> > Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> > ---
> >  Documentation/ABI/testing/sysfs-class-typec |  14 +++
> >  drivers/usb/typec/class.c                   | 123 +++++++++++++++++++-
> >  drivers/usb/typec/class.h                   |   2 +
> >  include/linux/usb/typec.h                   |   5 +
> >  4 files changed, 140 insertions(+), 4 deletions(-)
> 
> I think the use of port->usbN_dev is racy and not always obviouos.
> For example  on Qualcomm devices I ended up with no partner's
> usb_capability and just 'usb2' in usb_mode even though the partner uses
> USB3 mode. Maybe it's better to hide usb_mode completely if we can not
> properly determine the actual mode?
> 
> (On Qualcomm devices there is no working ACPI, so there is no USB <->
> typec correlationship (yet)).

Sure. Let's keep it hidden in that case.

thanks,

-- 
heikki