[v3,18/18] drm/tegra: Use the iommu dma_owner mechanism

Commit Message

Baolu Lu Dec. 6, 2021, 1:59 a.m. UTC

From: Jason Gunthorpe <[e-mail]>

Tegra joins many platform devices onto the same iommu_domain and builds
sort-of a DMA API on top of it.

Given that iommu_attach/detatch_device_shared() has supported this usage
model. Each device that wants to use the special domain will use
suppress_auto_claim_dma_owner and call iommu_attach_device_shared() which
will use dma owner framework to lock out other usages of the group and
refcount the domain attachment.

When the last device calls detatch the domain will be disconnected.

Signed-off-by: Jason Gunthorpe <[e-mail]>
Signed-off-by: Lu Baolu <[e-mail]>
Tested-by: Dmitry Osipenko <[e-mail]> # Nexus7 T30
---
 drivers/gpu/drm/tegra/dc.c   |  1 +
 drivers/gpu/drm/tegra/drm.c  | 55 ++++++++++++++++++------------------
 drivers/gpu/drm/tegra/gr2d.c |  1 +
 drivers/gpu/drm/tegra/gr3d.c |  1 +
 drivers/gpu/drm/tegra/vic.c  |  1 +
 5 files changed, 31 insertions(+), 28 deletions(-)

Comments

Jason Gunthorpe Dec. 6, 2021, 12:40 p.m. UTC | #1

On Mon, Dec 06, 2021 at 09:59:03AM +0800, Lu Baolu wrote:

> @@ -941,48 +944,44 @@ int host1x_client_iommu_attach(struct host1x_client *client)
>  	 * not the shared IOMMU domain, don't try to attach it to a different
>  	 * domain. This allows using the IOMMU-backed DMA API.
>  	 */
> -	if (domain && domain != tegra->domain)
> +	client->group = NULL;
> +	if (!client->dev->iommu_group || (domain && domain != tegra->domain))
> +		return iommu_device_set_dma_owner(client->dev,
> +						  DMA_OWNER_DMA_API, NULL);
> +
> +	if (!tegra->domain)
>  		return 0;

This if should be removed completely now

Jason

Baolu Lu Dec. 7, 2021, 2:34 a.m. UTC | #2

On 12/6/21 8:40 PM, Jason Gunthorpe wrote:
> On Mon, Dec 06, 2021 at 09:59:03AM +0800, Lu Baolu wrote:
> 
>> @@ -941,48 +944,44 @@ int host1x_client_iommu_attach(struct host1x_client *client)
>>   	 * not the shared IOMMU domain, don't try to attach it to a different
>>   	 * domain. This allows using the IOMMU-backed DMA API.
>>   	 */
>> -	if (domain && domain != tegra->domain)
>> +	client->group = NULL;
>> +	if (!client->dev->iommu_group || (domain && domain != tegra->domain))
>> +		return iommu_device_set_dma_owner(client->dev,
>> +						  DMA_OWNER_DMA_API, NULL);
>> +
>> +	if (!tegra->domain)
>>   		return 0;
> 
> This if should be removed completely now
> 
> Jason
> 

Sure.

Best regards,
baolu

Patch

diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
index a29d64f87563..3a2458f56fbc 100644
--- a/drivers/gpu/drm/tegra/dc.c
+++ b/drivers/gpu/drm/tegra/dc.c
@@ -3111,4 +3111,5 @@  struct platform_driver tegra_dc_driver = {
 	},
 	.probe = tegra_dc_probe,
 	.remove = tegra_dc_remove,
+	.suppress_auto_claim_dma_owner = true,
 };
diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index 8d37d6b00562..1e83e3f5da5b 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -928,12 +928,15 @@  int tegra_drm_unregister_client(struct tegra_drm *tegra,
 	return 0;
 }
 
+/*
+ * Clients which use this function must set suppress_auto_claim_dma_owner in
+ * their platform_driver's device_driver struct.
+ */
 int host1x_client_iommu_attach(struct host1x_client *client)
 {
 	struct iommu_domain *domain = iommu_get_domain_for_dev(client->dev);
 	struct drm_device *drm = dev_get_drvdata(client->host);
 	struct tegra_drm *tegra = drm->dev_private;
-	struct iommu_group *group = NULL;
 	int err;
 
 	/*
@@ -941,48 +944,44 @@  int host1x_client_iommu_attach(struct host1x_client *client)
 	 * not the shared IOMMU domain, don't try to attach it to a different
 	 * domain. This allows using the IOMMU-backed DMA API.
 	 */
-	if (domain && domain != tegra->domain)
+	client->group = NULL;
+	if (!client->dev->iommu_group || (domain && domain != tegra->domain))
+		return iommu_device_set_dma_owner(client->dev,
+						  DMA_OWNER_DMA_API, NULL);
+
+	if (!tegra->domain)
 		return 0;
 
-	if (tegra->domain) {
-		group = iommu_group_get(client->dev);
-		if (!group)
-			return -ENODEV;
-
-		if (domain != tegra->domain) {
-			err = iommu_attach_group(tegra->domain, group);
-			if (err < 0) {
-				iommu_group_put(group);
-				return err;
-			}
-		}
+	err = iommu_device_set_dma_owner(client->dev,
+					 DMA_OWNER_PRIVATE_DOMAIN, NULL);
+	if (err)
+		return err;
 
-		tegra->use_explicit_iommu = true;
+	err = iommu_attach_device_shared(tegra->domain, client->dev);
+	if (err) {
+		iommu_device_release_dma_owner(client->dev,
+					       DMA_OWNER_PRIVATE_DOMAIN);
+		return err;
 	}
 
-	client->group = group;
-
+	tegra->use_explicit_iommu = true;
+	client->group = client->dev->iommu_group;
 	return 0;
 }
 
 void host1x_client_iommu_detach(struct host1x_client *client)
 {
+	struct iommu_domain *domain = iommu_get_domain_for_dev(client->dev);
 	struct drm_device *drm = dev_get_drvdata(client->host);
 	struct tegra_drm *tegra = drm->dev_private;
-	struct iommu_domain *domain;
 
 	if (client->group) {
-		/*
-		 * Devices that are part of the same group may no longer be
-		 * attached to a domain at this point because their group may
-		 * have been detached by an earlier client.
-		 */
-		domain = iommu_get_domain_for_dev(client->dev);
-		if (domain)
-			iommu_detach_group(tegra->domain, client->group);
-
-		iommu_group_put(client->group);
+		iommu_detach_device_shared(tegra->domain, client->dev);
+		iommu_device_release_dma_owner(client->dev,
+					       DMA_OWNER_PRIVATE_DOMAIN);
 		client->group = NULL;
+	} else {
+		iommu_device_release_dma_owner(client->dev, DMA_OWNER_DMA_API);
 	}
 }
 
diff --git a/drivers/gpu/drm/tegra/gr2d.c b/drivers/gpu/drm/tegra/gr2d.c
index de288cba3905..8d92141c3c86 100644
--- a/drivers/gpu/drm/tegra/gr2d.c
+++ b/drivers/gpu/drm/tegra/gr2d.c
@@ -271,4 +271,5 @@  struct platform_driver tegra_gr2d_driver = {
 	},
 	.probe = gr2d_probe,
 	.remove = gr2d_remove,
+	.suppress_auto_claim_dma_owner = true,
 };
diff --git a/drivers/gpu/drm/tegra/gr3d.c b/drivers/gpu/drm/tegra/gr3d.c
index 24442ade0da3..33c4954977ab 100644
--- a/drivers/gpu/drm/tegra/gr3d.c
+++ b/drivers/gpu/drm/tegra/gr3d.c
@@ -400,4 +400,5 @@  struct platform_driver tegra_gr3d_driver = {
 	},
 	.probe = gr3d_probe,
 	.remove = gr3d_remove,
+	.suppress_auto_claim_dma_owner = true,
 };
diff --git a/drivers/gpu/drm/tegra/vic.c b/drivers/gpu/drm/tegra/vic.c
index c02010ff2b7f..114df067ea00 100644
--- a/drivers/gpu/drm/tegra/vic.c
+++ b/drivers/gpu/drm/tegra/vic.c
@@ -527,6 +527,7 @@  struct platform_driver tegra_vic_driver = {
 	},
 	.probe = vic_probe,
 	.remove = vic_remove,
+	.suppress_auto_claim_dma_owner = true,
 };
 
 #if IS_ENABLED(CONFIG_ARCH_TEGRA_124_SOC)