drm/tegra: vic: Load firmware on demand

Loading the firmware requires an allocation of IOVA space to make sure
that the VIC's Falcon microcontroller can read the firmware if address
translation via the SMMU is enabled.

However, the allocation currently happens at a time where the geometry
of an IOMMU domain may not have been initialized yet. This happens for
example on Tegra186 and later where an ARM SMMU is used. Domains which
are created by the ARM SMMU driver postpone the geometry setup until a
device is attached to the domain. This is because IOMMU domains aren't
attached to a specific IOMMU instance at allocation time and hence the
input address space, which defines the geometry, is not known yet.

Work around this by postponing the firmware load until it is needed at
the time where a channel is opened to the VIC. At this time the shared
IOMMU domain's geometry has been properly initialized.

As a byproduct this allows the Tegra DRM to be created in the absence
of VIC firmware, since the VIC initialization no longer fails if the
firmware can't be found.

Based on an earlier patch by Dmitry Osipenko <digetx@gmail.com>.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>

drivers/gpu/drm/tegra/vic.c

@@ -181,13 +181,6 @@ static int vic_init(struct host1x_client *client)
 		vic->domain = tegra->domain;
 	}
 
-	if (!vic->falcon.data) {
-		vic->falcon.data = tegra;
-		err = falcon_load_firmware(&vic->falcon);
-		if (err < 0)
-			goto detach;
-	}
-
 	vic->channel = host1x_channel_request(client->dev);
 	if (!vic->channel) {
 		err = -ENOMEM;
@@ -246,6 +239,30 @@ static const struct host1x_client_ops vic_client_ops = {
 	.exit = vic_exit,
 };
 
+static int vic_load_firmware(struct vic *vic)
+{
+	int err;
+
+	if (vic->falcon.data)
+		return 0;
+
+	vic->falcon.data = vic->client.drm;
+
+	err = falcon_read_firmware(&vic->falcon, vic->config->firmware);
+	if (err < 0)
+		goto cleanup;
+
+	err = falcon_load_firmware(&vic->falcon);
+	if (err < 0)
+		goto cleanup;
+
+	return 0;
+
+cleanup:
+	vic->falcon.data = NULL;
+	return err;
+}
+
 static int vic_open_channel(struct tegra_drm_client *client,
 			    struct tegra_drm_context *context)
 {
@@ -256,19 +273,25 @@ static int vic_open_channel(struct tegra_drm_client *client,
 	if (err < 0)
 		return err;
 
+	err = vic_load_firmware(vic);
+	if (err < 0)
+		goto rpm_put;
+
 	err = vic_boot(vic);
-	if (err < 0) {
-		pm_runtime_put(vic->dev);
-		return err;
-	}
+	if (err < 0)
+		goto rpm_put;
 
 	context->channel = host1x_channel_get(vic->channel);
 	if (!context->channel) {
-		pm_runtime_put(vic->dev);
-		return -ENOMEM;
+		err = -ENOMEM;
+		goto rpm_put;
 	}
 
 	return 0;
+
+rpm_put:
+	pm_runtime_put(vic->dev);
+	return err;
 }
 
 static void vic_close_channel(struct tegra_drm_context *context)
@@ -372,10 +395,6 @@ static int vic_probe(struct platform_device *pdev)
 	if (err < 0)
 		return err;
 
-	err = falcon_read_firmware(&vic->falcon, vic->config->firmware);
-	if (err < 0)
-		goto exit_falcon;
-
 	platform_set_drvdata(pdev, vic);
 
 	INIT_LIST_HEAD(&vic->client.base.list);