Re: [PATCH v2 6/7] drm/bridge: anx7625: Register Type-C mode switches

[AngeloGioacchino Del Regno]

Il 14/06/22 18:57, Prashant Malani ha scritto:
> On Tue, Jun 14, 2022 at 1:18 AM AngeloGioacchino Del Regno
> <angelogioacchino.delregno@xxxxxxxxxxxxx> wrote:
> > Il 09/06/22 20:09, Prashant Malani ha scritto:
> > > When the DT node has "switches" available, register a Type-C mode-switch
> > > for each listed "switch". This allows the driver to receive state
> > > information about what operating mode a Type-C port and its connected
> > > peripherals are in, as well as status information (like VDOs) related to
> > > that state.
> > >
> > > The callback function is currently a stub, but subsequent patches will
> > > implement the required functionality.
> > >
> > > Signed-off-by: Prashant Malani <pmalani@xxxxxxxxxxxx>
> > > ---
> > >
> > > Changes since v2:
> > > - No changes.
> > >
> > >    drivers/gpu/drm/bridge/analogix/anx7625.c | 73 +++++++++++++++++++++++
> > >    drivers/gpu/drm/bridge/analogix/anx7625.h |  6 ++
> > >    2 files changed, 79 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
> > > index 07ed44c6b839..d41a21103bd3 100644
> > > --- a/drivers/gpu/drm/bridge/analogix/anx7625.c
> > > +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
> > > @@ -15,6 +15,7 @@
> > >    #include <linux/regulator/consumer.h>
> > >    #include <linux/slab.h>
> > >    #include <linux/types.h>
> > > +#include <linux/usb/typec_mux.h>
> > >    #include <linux/workqueue.h>
> > >
> > >    #include <linux/of_gpio.h>
> > > @@ -2581,9 +2582,59 @@ static void anx7625_runtime_disable(void *data)
> > >        pm_runtime_disable(data);
> > >    }
> > >
> > > +static int anx7625_typec_mux_set(struct typec_mux_dev *mux,
> > > +                              struct typec_mux_state *state)
> > > +{
> > > +     return 0;
> > > +}
> > > +
> > > +static int anx7625_register_mode_switch(struct device *dev, struct device_node *node,
> > > +                                     struct anx7625_data *ctx)
> > > +{
> > > +     struct anx7625_port_data *port_data;
> > > +     struct typec_mux_desc mux_desc = {};
> > > +     char name[32];
> > > +     u32 port_num;
> > > +     int ret;
> > > +
> > > +     ret = of_property_read_u32(node, "reg", &port_num);
> > > +     if (ret)
> > > +             return ret;
> > > +
> > > +     if (port_num >= ctx->num_typec_switches) {
> > > +             dev_err(dev, "Invalid port number specified: %d\n", port_num);
> > > +             return -EINVAL;
> > > +     }
> > > +
> > > +     port_data = &ctx->typec_ports[port_num];
> > > +     port_data->ctx = ctx;
> > > +     mux_desc.fwnode = &node->fwnode;
> > > +     mux_desc.drvdata = port_data;
> > > +     snprintf(name, sizeof(name), "%s-%u", node->name, port_num);
> > > +     mux_desc.name = name;
> > > +     mux_desc.set = anx7625_typec_mux_set;
> > > +
> > > +     port_data->typec_mux = typec_mux_register(dev, &mux_desc);
> > > +     if (IS_ERR(port_data->typec_mux)) {
> > > +             ret = PTR_ERR(port_data->typec_mux);
> > > +             dev_err(dev, "Mode switch register for port %d failed: %d", port_num, ret);
> > > +     }
> >
> > Please return 0 at the end of this function.
> >
> >          if (IS_ERR(....)) {
> >                  ......code......
> >                  return ret;
> >          }
> >
> >          return 0;
> > }
>
> May I ask why? We're not missing any return paths. I would rather we
> keep it as is (which has the valid return value).

I know that you're not missing any return paths.

That's only because the proposed one is a common pattern in the kernel
and it's only for consistency.

Regards,
Angelo