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authorDave Airlie <airlied@redhat.com>2020-05-14 12:29:45 +1000
committerDave Airlie <airlied@redhat.com>2020-05-14 12:29:50 +1000
commit6da9b046af6f2e6b22f5f768e374ee1137dfb250 (patch)
tree297b59a0a46e0367e9490b80bc08821625dee158 /drivers
parent0c77ca2f9d87b5ba0f93324cd678aeb5de528399 (diff)
parent4010e729349fcab69183f338fe3743df17a473a0 (diff)
downloadlinux-sh-6da9b046af6f2e6b22f5f768e374ee1137dfb250.tar.gz
Merge tag 'drm/tegra/for-5.7-fixes' of git://anongit.freedesktop.org/tegra/linux into drm-fixes
drm/tegra: Fixes for v5.7 This contains a pair of patches which fix SMMU support on Tegra124 and Tegra210 for host1x and the Tegra DRM driver. Signed-off-by: Dave Airlie <airlied@redhat.com> From: Thierry Reding <thierry.reding@gmail.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200508101355.3031268-1-thierry.reding@gmail.com
Diffstat (limited to 'drivers')
-rw-r--r--drivers/gpu/drm/tegra/drm.c3
-rw-r--r--drivers/gpu/host1x/dev.c59
2 files changed, 57 insertions, 5 deletions
diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index bd268028fb3d..583cd6e0ae27 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -1039,6 +1039,7 @@ void tegra_drm_free(struct tegra_drm *tegra, size_t size, void *virt,
static bool host1x_drm_wants_iommu(struct host1x_device *dev)
{
+ struct host1x *host1x = dev_get_drvdata(dev->dev.parent);
struct iommu_domain *domain;
/*
@@ -1076,7 +1077,7 @@ static bool host1x_drm_wants_iommu(struct host1x_device *dev)
* sufficient and whether or not the host1x is attached to an IOMMU
* doesn't matter.
*/
- if (!domain && dma_get_mask(dev->dev.parent) <= DMA_BIT_MASK(32))
+ if (!domain && host1x_get_dma_mask(host1x) <= DMA_BIT_MASK(32))
return true;
return domain != NULL;
diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
index 388bcc2889aa..d24344e91922 100644
--- a/drivers/gpu/host1x/dev.c
+++ b/drivers/gpu/host1x/dev.c
@@ -192,17 +192,55 @@ static void host1x_setup_sid_table(struct host1x *host)
}
}
+static bool host1x_wants_iommu(struct host1x *host1x)
+{
+ /*
+ * If we support addressing a maximum of 32 bits of physical memory
+ * and if the host1x firewall is enabled, there's no need to enable
+ * IOMMU support. This can happen for example on Tegra20, Tegra30
+ * and Tegra114.
+ *
+ * Tegra124 and later can address up to 34 bits of physical memory and
+ * many platforms come equipped with more than 2 GiB of system memory,
+ * which requires crossing the 4 GiB boundary. But there's a catch: on
+ * SoCs before Tegra186 (i.e. Tegra124 and Tegra210), the host1x can
+ * only address up to 32 bits of memory in GATHER opcodes, which means
+ * that command buffers need to either be in the first 2 GiB of system
+ * memory (which could quickly lead to memory exhaustion), or command
+ * buffers need to be treated differently from other buffers (which is
+ * not possible with the current ABI).
+ *
+ * A third option is to use the IOMMU in these cases to make sure all
+ * buffers will be mapped into a 32-bit IOVA space that host1x can
+ * address. This allows all of the system memory to be used and works
+ * within the limitations of the host1x on these SoCs.
+ *
+ * In summary, default to enable IOMMU on Tegra124 and later. For any
+ * of the earlier SoCs, only use the IOMMU for additional safety when
+ * the host1x firewall is disabled.
+ */
+ if (host1x->info->dma_mask <= DMA_BIT_MASK(32)) {
+ if (IS_ENABLED(CONFIG_TEGRA_HOST1X_FIREWALL))
+ return false;
+ }
+
+ return true;
+}
+
static struct iommu_domain *host1x_iommu_attach(struct host1x *host)
{
struct iommu_domain *domain = iommu_get_domain_for_dev(host->dev);
int err;
/*
- * If the host1x firewall is enabled, there's no need to enable IOMMU
- * support. Similarly, if host1x is already attached to an IOMMU (via
- * the DMA API), don't try to attach again.
+ * We may not always want to enable IOMMU support (for example if the
+ * host1x firewall is already enabled and we don't support addressing
+ * more than 32 bits of physical memory), so check for that first.
+ *
+ * Similarly, if host1x is already attached to an IOMMU (via the DMA
+ * API), don't try to attach again.
*/
- if (IS_ENABLED(CONFIG_TEGRA_HOST1X_FIREWALL) || domain)
+ if (!host1x_wants_iommu(host) || domain)
return domain;
host->group = iommu_group_get(host->dev);
@@ -502,6 +540,19 @@ static void __exit tegra_host1x_exit(void)
}
module_exit(tegra_host1x_exit);
+/**
+ * host1x_get_dma_mask() - query the supported DMA mask for host1x
+ * @host1x: host1x instance
+ *
+ * Note that this returns the supported DMA mask for host1x, which can be
+ * different from the applicable DMA mask under certain circumstances.
+ */
+u64 host1x_get_dma_mask(struct host1x *host1x)
+{
+ return host1x->info->dma_mask;
+}
+EXPORT_SYMBOL(host1x_get_dma_mask);
+
MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
MODULE_AUTHOR("Terje Bergstrom <tbergstrom@nvidia.com>");
MODULE_DESCRIPTION("Host1x driver for Tegra products");