Re: [PATCH v3 4/6] typec: mux: Allow multiple mux_devs per mux

Bjorn Andersson
2022-03-07T03:09:12Z

On Fri 04 Mar 07:54 CST 2022, Andy Shevchenko wrote:

> On Thu, Mar 03, 2022 at 02:33:49PM -0800, Bjorn Andersson wrote:
> > In the Qualcomm platforms the USB/DP PHY handles muxing and orientation
> > switching of the SuperSpeed lines, but the SBU lines needs to be
> > connected and switched by external (to the SoC) hardware.
> >
> > It's therefor necessary to be able to have the TypeC controller operate
> > multiple TypeC muxes and switches. Use the newly introduced indirection
> > object to handle this, to avoid having to taint the TypeC controllers
> > with knowledge about the downstream hardware configuration.
> >
> > The max number of devs per indirection is set to 3, which account for
> > being able to mux/switch the USB HS, SS and SBU lines, as per defined
> > defined in the usb-c-connector binding. This number could be grown if
> > need arrises at a later point in time.
>
> ...
>
> > + for (i = 0; i < count; i++) {
> > + if (IS_ERR(sw_devs[i])) {
> > + err = PTR_ERR(sw_devs[i]);
> > + goto put_sw_devs;
> > + }
> > + }
> >
> > - sw->sw_dev = sw_dev;
> > + for (i = 0; i < count; i++) {
> > + WARN_ON(!try_module_get(sw_devs[i]->dev.parent->driver->owner));
> > + sw->sw_devs[i] = sw_devs[i];
> > + }
> > +
> > + sw->num_sw_devs = count;
> >
> > return sw;
> > +
> > +put_sw_devs:
> > + for (i = 0; i < count; i++) {
>
> Shouldn't it be
>
> while (i--)
>
> ?

fwnode_connection_find_matches() "returned" count number of sw_devs, we
need to put_device() them all. So that form could have been

while (count--)

but as it's not the typical "unrolling" I think the untypical form is
more useful.

>
> > + if (!IS_ERR(sw_devs[i]))
>
> We may get rid of this check if we guarantee that the device is NULL.
>

In the event that the USB Type-C controller probes before some of the
muxes, this array might contain one or more entries of EPROBE_DEFER.

So we need to either put this conditional here, or we need to loop
through all entries to turn IS_ERR() into NULL, for the sake of not
having it here.

So to me this looks cleaner...

Regards,
Bjorn

> > + put_device(&sw_devs[i]->dev);
> > + }
> > +
> > + kfree(sw);
> > +
> > + return ERR_PTR(err);
> > }
>
> ...
>
> > + for (i = 0; i < count; i++) {
> > + if (IS_ERR(mux_devs[i])) {
> > + err = PTR_ERR(mux_devs[i]);
> > + goto put_mux_devs;
> > + }
>
> Ditto.
>
> > + }
>
> ...
>
> > +put_mux_devs:
> > + for (i = 0; i < count; i++) {
> > + if (!IS_ERR(mux_devs[i]))
> > + put_device(&mux_devs[i]->dev);
> > + }
>
> Ditto.
>
> --
> With Best Regards,
> Andy Shevchenko
>
>