From 0c74805812521ba63c0b85398e38f492724cb5ab Mon Sep 17 00:00:00 2001
From: Mikko Perttunen <mperttunen@nvidia.com>
Date: Thu, 10 Jun 2021 14:04:50 +0300
Subject: drm/tegra: Allocate per-engine channel in core code
Git-commit: e0f2977c35733fcccafdabcc02bf4f6ddf7f438d
Patch-mainline: v5.15-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

To avoid code duplication, allocate the per-engine shared channel in
the core code instead. This is the usual channel that all jobs are
submitted to when MLOCKing is not in use. Once MLOCKs are implemented
on Host1x side, we can also update this to avoid allocating a shared
channel when MLOCKs are enabled.

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/tegra/drm.c | 11 +++++++++++
 drivers/gpu/drm/tegra/drm.h |  2 ++
 2 files changed, 13 insertions(+)

diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index c01fd10e6240..6fb199352658 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -870,6 +870,14 @@ static const struct drm_driver tegra_drm_driver = {
 int tegra_drm_register_client(struct tegra_drm *tegra,
 			      struct tegra_drm_client *client)
 {
+	/*
+	 * When MLOCKs are implemented, change to allocate a shared channel
+	 * only when MLOCKs are disabled.
+	 */
+	client->shared_channel = host1x_channel_request(&client->base);
+	if (!client->shared_channel)
+		return -EBUSY;
+
 	mutex_lock(&tegra->clients_lock);
 	list_add_tail(&client->list, &tegra->clients);
 	client->drm = tegra;
@@ -886,6 +894,9 @@ int tegra_drm_unregister_client(struct tegra_drm *tegra,
 	client->drm = NULL;
 	mutex_unlock(&tegra->clients_lock);
 
+	if (client->shared_channel)
+		host1x_channel_put(client->shared_channel);
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/tegra/drm.h b/drivers/gpu/drm/tegra/drm.h
index 0cb868065348..536861017d24 100644
--- a/drivers/gpu/drm/tegra/drm.h
+++ b/drivers/gpu/drm/tegra/drm.h
@@ -91,7 +91,9 @@ struct tegra_drm_client {
 	struct host1x_client base;
 	struct list_head list;
 	struct tegra_drm *drm;
+	struct host1x_channel *shared_channel;
 
+	/* Set by driver */
 	unsigned int version;
 	const struct tegra_drm_client_ops *ops;
 };
-- 
2.38.1