On 2021-08-26 13:10, Michael Walle wrote:
The DMA configuration of the virtual device is inherited from the first
actual etnaviv device. Unfortunately, this doesn't work with an IOMMU:
[ 5.191008] Failed to set up IOMMU for device (null); retaining platform DMA ops
This is because there is no associated iommu_group with the device. The
group is set in iommu_group_add_device() which is eventually called by
device_add() via the platform bus:
device_add()
blocking_notifier_call_chain()
iommu_bus_notifier()
iommu_probe_device()
__iommu_probe_device()
iommu_group_get_for_dev()
iommu_group_add_device()
Move of_dma_configure() into the probe function, which is called after
device_add(). Normally, the platform code will already call it itself
if .of_node is set. Unfortunately, this isn't the case here.
Also move the dma mask assignemnts to probe() to keep all DMA related
settings together.
I assume the driver must already keep track of the real GPU platform
device in order to map registers, request interrupts, etc. correctly -
can't it also correctly use that device for DMA API calls and avoid the
need for these shenanigans altogether?
FYI, IOMMU configuration is really supposed to *only* run at
add_device() time as above - the fact that it's currently hooked in to
be retriggered by of_dma_configure() on DT platforms actually turns out
to lead to various issues within the IOMMU API, and the plan to change
that is slowly climbing up my to-do list.
Robin.
Signed-off-by: Michael Walle <michael@xxxxxxxx>
---
drivers/gpu/drm/etnaviv/etnaviv_drv.c | 24 +++++++++++++++---------
1 file changed, 15 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.c b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
index 2509b3e85709..ff6425f6ebad 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_drv.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
@@ -589,6 +589,7 @@ static int compare_str(struct device *dev, void *data)
static int etnaviv_pdev_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
+ struct device_node *first_node = NULL;
struct component_match *match = NULL;
if (!dev->platform_data) {
@@ -598,6 +599,9 @@ static int etnaviv_pdev_probe(struct platform_device *pdev)
if (!of_device_is_available(core_node))
continue;
+ if (!first_node)
+ first_node = core_node;
+
drm_of_component_match_add(&pdev->dev, &match,
compare_of, core_node);
}
@@ -609,6 +613,17 @@ static int etnaviv_pdev_probe(struct platform_device *pdev)
component_match_add(dev, &match, compare_str, names[i]);
}
+ pdev->dev.coherent_dma_mask = DMA_BIT_MASK(40);
+ pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
+
+ /*
+ * Apply the same DMA configuration to the virtual etnaviv
+ * device as the GPU we found. This assumes that all Vivante
+ * GPUs in the system share the same DMA constraints.
+ */
+ if (first_node)
+ of_dma_configure(&pdev->dev, first_node, true);
+
return component_master_add_with_match(dev, &etnaviv_master_ops, match);
}
@@ -659,15 +674,6 @@ static int __init etnaviv_init(void)
of_node_put(np);
goto unregister_platform_driver;
}
- pdev->dev.coherent_dma_mask = DMA_BIT_MASK(40);
- pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
-
- /*
- * Apply the same DMA configuration to the virtual etnaviv
- * device as the GPU we found. This assumes that all Vivante
- * GPUs in the system share the same DMA constraints.
- */
- of_dma_configure(&pdev->dev, np, true);
ret = platform_device_add(pdev);
if (ret) {
