drm/amd/display: Add logging for aux DPCD access

Add basic logging for DPCD access. Does not print
by default.

Currently only prints first byte of the data accessed.

Technical debt: Need to make it so that the entire
data block accessed is printed. Also need to log
address space that's not DPCD.

Signed-off-by: Eric Yang <Eric.Yang2@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/i2caux/aux_engine.c

@@ -284,6 +284,14 @@ static bool read_command(
 				msleep(engine->delay);
 	} while (ctx.operation_succeeded && !ctx.transaction_complete);
 
+	if (request->payload.address_space ==
+		I2CAUX_TRANSACTION_ADDRESS_SPACE_DPCD) {
+		dm_logger_write(engine->base.ctx->logger, LOG_I2C_AUX, "READ: addr:0x%x  value:0x%x Result:%d",
+				request->payload.address,
+				request->payload.data[0],
+				ctx.operation_succeeded);
+	}
+
 	return ctx.operation_succeeded;
 }
 
@@ -484,6 +492,14 @@ static bool write_command(
 				msleep(engine->delay);
 	} while (ctx.operation_succeeded && !ctx.transaction_complete);
 
+	if (request->payload.address_space ==
+		I2CAUX_TRANSACTION_ADDRESS_SPACE_DPCD) {
+		dm_logger_write(engine->base.ctx->logger, LOG_I2C_AUX, "WRITE: addr:0x%x  value:0x%x Result:%d",
+				request->payload.address,
+				request->payload.data[0],
+				ctx.operation_succeeded);
+	}
+
 	return ctx.operation_succeeded;
 }