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Subject[PATCH v5 1/3] drm/nouveau: set streaming DMA mask early
Date
Some subdevices (i.e., fb/nv50.c and fb/gf100.c) map a scratch page using
dma_map_page() way before the TTM layer has had a chance to set the DMA
mask. This may prevent the driver from loading at all on platforms whose
system memory is not covered by the default DMA mask of 32-bit (i.e., when
all RAM is above 4 GB).

So set a preliminary DMA mask right after constructing the PCI device, and
base it on the .dma_bits member of the MMU subdevice, which is what the TTM
layer will base the DMA mask on as well.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
drivers/gpu/drm/nouveau/nvkm/engine/device/pci.c | 37 ++++++++++++++------
1 file changed, 27 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/device/pci.c b/drivers/gpu/drm/nouveau/nvkm/engine/device/pci.c
index 62ad0300cfa5..0030cd9543b2 100644
--- a/drivers/gpu/drm/nouveau/nvkm/engine/device/pci.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/device/pci.c
@@ -1665,14 +1665,31 @@ nvkm_device_pci_new(struct pci_dev *pci_dev, const char *cfg, const char *dbg,
*pdevice = &pdev->device;
pdev->pdev = pci_dev;

- return nvkm_device_ctor(&nvkm_device_pci_func, quirk, &pci_dev->dev,
- pci_is_pcie(pci_dev) ? NVKM_DEVICE_PCIE :
- pci_find_capability(pci_dev, PCI_CAP_ID_AGP) ?
- NVKM_DEVICE_AGP : NVKM_DEVICE_PCI,
- (u64)pci_domain_nr(pci_dev->bus) << 32 |
- pci_dev->bus->number << 16 |
- PCI_SLOT(pci_dev->devfn) << 8 |
- PCI_FUNC(pci_dev->devfn), name,
- cfg, dbg, detect, mmio, subdev_mask,
- &pdev->device);
+ ret = nvkm_device_ctor(&nvkm_device_pci_func, quirk, &pci_dev->dev,
+ pci_is_pcie(pci_dev) ? NVKM_DEVICE_PCIE :
+ pci_find_capability(pci_dev, PCI_CAP_ID_AGP) ?
+ NVKM_DEVICE_AGP : NVKM_DEVICE_PCI,
+ (u64)pci_domain_nr(pci_dev->bus) << 32 |
+ pci_dev->bus->number << 16 |
+ PCI_SLOT(pci_dev->devfn) << 8 |
+ PCI_FUNC(pci_dev->devfn), name,
+ cfg, dbg, detect, mmio, subdev_mask,
+ &pdev->device);
+
+ if (ret)
+ return ret;
+
+ /*
+ * Set a preliminary DMA mask based on the .dma_bits member of the
+ * MMU subdevice. This allows other subdevices to create DMA mappings
+ * in their init() or oneinit() methods, which may be called before the
+ * TTM layer sets the DMA mask definitively.
+ * This is necessary for platforms where the default DMA mask of 32
+ * does not cover any system memory, i.e., when all RAM is > 4 GB.
+ */
+ if (subdev_mask & BIT(NVKM_SUBDEV_MMU))
+ dma_set_mask_and_coherent(&pci_dev->dev,
+ DMA_BIT_MASK(pdev->device.mmu->dma_bits));
+
+ return 0;
}
--
2.7.4
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