Re: [PATCH v2 7/7] drm/bridge: anx7625: Add typec_mux_set callback function

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Il 14/06/22 18:58, Prashant Malani ha scritto:
On Tue, Jun 14, 2022 at 2:08 AM Pin-yen Lin <treapking@xxxxxxxxxxxx> wrote:

Hi AngeloGioacchino,


On Tue, Jun 14, 2022 at 4:15 PM AngeloGioacchino Del Regno
<angelogioacchino.delregno@xxxxxxxxxxxxx> wrote:

Il 09/06/22 20:09, Prashant Malani ha scritto:
From: Pin-Yen Lin <treapking@xxxxxxxxxxxx>

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.

Signed-off-by: Pin-Yen Lin <treapking@xxxxxxxxxxxx>
Signed-off-by: Prashant Malani <pmalani@xxxxxxxxxxxx>
---

Changes since v2:
- No changes.

   drivers/gpu/drm/bridge/analogix/anx7625.c | 58 +++++++++++++++++++++++
   drivers/gpu/drm/bridge/analogix/anx7625.h | 13 +++++
   2 files changed, 71 insertions(+)

diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
index d41a21103bd3..2c308d12fab2 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 +2583,66 @@ 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 old_dp_connected = (ctx->typec_ports[0].dp_connected ||
+                              ctx->typec_ports[1].dp_connected);

So the old connection state is "either port0 or port1 are currently connected"...

+     bool new_dp_connected;
+
+     if (ctx->num_typec_switches == 1)
+             return 0;
+
+     dev_dbg(dev, "mux_set dp_connected: c0=%d, c1=%d\n",
+             ctx->typec_ports[0].dp_connected, ctx->typec_ports[1].dp_connected);
+
+     data->dp_connected = (state->alt && state->alt->svid == USB_TYPEC_DP_SID &&
+                           state->alt->mode == USB_TYPEC_DP_MODE);
+ > + new_dp_connected = (ctx->typec_ports[0].dp_connected ||
+                         ctx->typec_ports[1].dp_connected);

...and the new connection state is the same as the old one, because I don't see
anything that could ever modify it in this function's flow, until reaching this
assignment.

The typec mux driver data (`struct anx7625_port_data *data =
typec_mux_get_drvdata(mux)`) is set to one of the
`ctx->typec_ports[*]` in `anx7625_register_mode_switch` (see patch 6
of this series).

So, the `data->dp_connected = ...` assignment may change the new
connection state.

Angelo, I think your interpretation of this logic is not accurate..
|old_dp_connected| represents *whether* port1 or port0 has a DP
partner connected, not that *either* of them has it.

So, this logic looks OK to me.


Hello Prashant,

You're completely right: I've finally seen where this is happening, so yes
we don't know, nor care at that moment, whether data->dp_connected is port0
or port1, we assign and check 'em both again, which is actually smart.

I'm sorry for the misunderstandment - and thank you for your reply.

Feel free to add my

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>

Regards,
Angelo



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