Re: [PATCH v5 5/9] drm/bridge: anx7625: Add typec_mux_set callback function

[Prashant Malani <pmalani@chromium.org>]

On Tue, Jun 28, 2022 at 12:25 PM Stephen Boyd <swboyd@chromium.org> wrote:
>
> Quoting Prashant Malani (2022-06-22 10:34:34)
> > From: Pin-Yen Lin <treapking@chromium.org>
> >
> > Add the callback function when the driver receives state
> > changes of the Type-C port. The callback function configures the
> > crosspoint switch of the anx7625 bridge chip, which can change the
> > output pins of the signals according to the port state.
>
> Can this be combined with the previous two patches? They really don't
> stand alone because the previous two patches are adding stubs that are
> filled out later.

I split it out for ease of reviewing, but sure, I will combine it if
there is a v6.

>
> > diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
> > index bd21f159b973..5992fc8beeeb 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_dp.h>
> >  #include <linux/usb/typec_mux.h>
> >  #include <linux/workqueue.h>
> >
> > @@ -2582,9 +2583,64 @@ static void anx7625_runtime_disable(void *data)
> >         pm_runtime_disable(data);
> >  }
> >
> > +static void anx7625_set_crosspoint_switch(struct anx7625_data *ctx,
> > +                                         enum typec_orientation orientation)
> > +{
> > +       if (orientation == TYPEC_ORIENTATION_NORMAL) {
> > +               anx7625_reg_write(ctx, ctx->i2c.tcpc_client, TCPC_SWITCH_0,
> > +                                 SW_SEL1_SSRX_RX1 | SW_SEL1_DPTX0_RX2);
> > +               anx7625_reg_write(ctx, ctx->i2c.tcpc_client, TCPC_SWITCH_1,
> > +                                 SW_SEL2_SSTX_TX1 | SW_SEL2_DPTX1_TX2);
> > +       } else if (orientation == TYPEC_ORIENTATION_REVERSE) {
> > +               anx7625_reg_write(ctx, ctx->i2c.tcpc_client, TCPC_SWITCH_0,
> > +                                 SW_SEL1_SSRX_RX2 | SW_SEL1_DPTX0_RX1);
> > +               anx7625_reg_write(ctx, ctx->i2c.tcpc_client, TCPC_SWITCH_1,
> > +                                 SW_SEL2_SSTX_TX2 | SW_SEL2_DPTX1_TX1);
> > +       }
> > +}
> > +
> > +static void anx7625_typec_two_ports_update(struct anx7625_data *ctx)
> > +{
> > +       if (ctx->typec_ports[0].dp_connected && ctx->typec_ports[1].dp_connected)
> > +               /* Both ports available, do nothing to retain the current one. */
> > +               return;
> > +       else if (ctx->typec_ports[0].dp_connected)
> > +               anx7625_set_crosspoint_switch(ctx, TYPEC_ORIENTATION_NORMAL);
> > +       else if (ctx->typec_ports[1].dp_connected)
> > +               anx7625_set_crosspoint_switch(ctx, TYPEC_ORIENTATION_REVERSE);
> > +}
> > +
> >  static int anx7625_typec_mux_set(struct typec_mux_dev *mux,
> >                                  struct typec_mux_state *state)
> >  {
> > +       struct anx7625_port_data *data = typec_mux_get_drvdata(mux);
> > +       struct anx7625_data *ctx = data->ctx;
> > +       struct device *dev = &ctx->client->dev;
> > +       bool new_dp_connected, old_dp_connected;
> > +
> > +       if (ctx->num_typec_switches == 1)
>
> How do we handle the case where the usb-c-connector is directly
> connected to the RX1/TX1 and RX2/TX2 pins? This device would be an
> orientation (normal/reverse) and mode switch (usb/dp) in that scenario,
> but this code is written in a way that the orientation switch isn't
> going to flip the crosspoint switch for the different pin assignments.

If all 4 SS lanes are connected to 1 usb-c-connector; there would be
just 1 "typec-switch" node.
In that case, the DT would only specify it as an "orientation-switch"
and register
an orientation-switch with the Type-C framework. The orientation switch would
pretty much do what the mode-switch callback does here (configuring
the crosspoint
switch).
One could also register a "mode-switch" there but it wouldn't do
anything (all 4 lanes are already
connected so there is nothing to re-route in the crosspoint switch).
Hence the above "if" check.

Unfortunately, I don't have hardware which connects all 4 SS lanes
from 1 Type-C port
to the anx7625, so I didn't add the orientation switch handling to the
driver (since I have no way of verifying it).

Regarding DP alt-mode pin assignments : I think anx7625 will only support Pin D
(only 2 lane DP, no 4 lane DP).

BR,

-Prashant