drm/tegra: dpaux: Populate AUX bus

The DPAUX hardware block exposes an DP AUX interface that provides
access to an AUX bus and the devices on that bus. Use the DP AUX bus
infrastructure that was recently introduced to probe devices on this
bus from DT.
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/tegra/Kconfig

@@ -5,6 +5,7 @@ config DRM_TEGRA
 	depends on COMMON_CLK
 	depends on DRM
 	depends on OF
+	select DRM_DP_AUX_BUS
 	select DRM_KMS_HELPER
 	select DRM_MIPI_DSI
 	select DRM_PANEL

drivers/gpu/drm/tegra/dpaux.c

@@ -19,6 +19,7 @@
 #include <linux/workqueue.h>
 
 #include <drm/drm_dp_helper.h>
+#include <drm/drm_dp_aux_bus.h>
 #include <drm/drm_panel.h>
 
 #include "dp.h"
@@ -570,6 +571,12 @@ static int tegra_dpaux_probe(struct platform_device *pdev)
 	list_add_tail(&dpaux->list, &dpaux_list);
 	mutex_unlock(&dpaux_lock);
 
+	err = devm_of_dp_aux_populate_ep_devices(&dpaux->aux);
+	if (err < 0) {
+		dev_err(dpaux->dev, "failed to populate AUX bus: %d\n", err);
+		return err;
+	}
+
 	return 0;
 }