On Thu, 12 Dec 2019, Felipe Balbi wrote:
> Hi,
>
> Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> writes:
> > Introduce gadget opts udc_set_sublink_speed callback to set the lane
> > count and transfer rate (in lane speed mantissa of Gbps) for SuperSpeed
> > Plus capable gadgets. In the same way udc_set_speed, this function can
> > control the gadget's sublink attributes for SuperSpeed Plus.
> >
> > Signed-off-by: Thinh Nguyen <thinhn@xxxxxxxxxxxx>
> > ---
> > drivers/usb/gadget/composite.c | 2 ++
> > drivers/usb/gadget/legacy/mass_storage.c | 2 ++
>
> I would rather not add new features to the legacy gadgets and focus on
> our configfs interface for anything new. Moreover, using the feature
> you introduced could, arguably, be done as a separate patch.
>
> > diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
> > index 3b4f67000315..a4de5a8c0f19 100644
> > --- a/drivers/usb/gadget/composite.c
> > +++ b/drivers/usb/gadget/composite.c
> > @@ -2353,6 +2353,8 @@ int usb_composite_probe(struct usb_composite_driver *driver)
> > gadget_driver->function = (char *) driver->name;
> > gadget_driver->driver.name = driver->name;
> > gadget_driver->max_speed = driver->max_speed;
> > + gadget_driver->max_lane_count = driver->max_lane_count;
> > + gadget_driver->max_lsm = driver->max_lsm;
> >
> > return usb_gadget_probe_driver(gadget_driver);
> > }
> > diff --git a/drivers/usb/gadget/legacy/mass_storage.c b/drivers/usb/gadget/legacy/mass_storage.c
> > index f18f77584fc2..a0912c5afffc 100644
> > --- a/drivers/usb/gadget/legacy/mass_storage.c
> > +++ b/drivers/usb/gadget/legacy/mass_storage.c
> > @@ -223,6 +223,8 @@ static struct usb_composite_driver msg_driver = {
> > .name = "g_mass_storage",
> > .dev = &msg_device_desc,
> > .max_speed = USB_SPEED_SUPER_PLUS,
> > + .max_lane_count = 2,
> > + .max_lsm = 10,
>
> Right, as mentioned, I'd prefer not touch the legacy gadgets. But in any
> case, why is it so that the gadget is telling you about max lane count
> and lsm? That should be abstracted away from the gadget driver. Gadget
> driver shouldn't have knowledge of number of lanes because, at the end
> of the day, that doesn't really change anything in practice. Unlike HS
> vs SS which changes a bunch of things.
I agree completely. Furthermore, it isn't at all clear where those two
numbers came from. Why would g-mass-storage care that lane_count <= 2
and lsm <= 10?
Alan Stern
