[v2] instmem/gk20a: set DMA mask early

Submitted by Alexandre Courbot on Feb. 25, 2016, 6:08 a.m.


Message ID 1456380522-17520-1-git-send-email-acourbot@nvidia.com
State New
Headers show
Series "instmem/gk20a: set DMA mask early" ( rev: 1 ) in Nouveau

Browsing this patch as part of:
"instmem/gk20a: set DMA mask early" rev 1 in Nouveau
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Commit Message

Alexandre Courbot Feb. 25, 2016, 6:08 a.m.
DMA mask is typically set in nouveau_ttm_init(), but this function is
called late during initialization and GK20A's instmem will have called
DMA functions before this happens.

Having a wrongly set DMA mask can result in the use of unneeded bounce
buffers. Set it early to avoid this.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Changes since v1:
- Set mask in tegra.c instead of instmem, as suggested by Ben.

 drm/nouveau/nvkm/engine/device/tegra.c | 9 +++++++++
 1 file changed, 9 insertions(+)

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diff --git a/drm/nouveau/nvkm/engine/device/tegra.c b/drm/nouveau/nvkm/engine/device/tegra.c
index 6d89416f0bc1..e1cd665aee2c 100644
--- a/drm/nouveau/nvkm/engine/device/tegra.c
+++ b/drm/nouveau/nvkm/engine/device/tegra.c
@@ -272,6 +272,15 @@  nvkm_device_tegra_new(const struct nvkm_device_tegra_func *func,
 	if (IS_ERR(tdev->clk_pwr))
 		return PTR_ERR(tdev->clk_pwr);
+	/**
+	 * The IOMMU bit defines the upper limit of the GPU-addressable space.
+	 * This will be refined in nouveau_ttm_init but we need to do it early
+	 * for instmem to behave properly
+	 */
+	ret = dma_set_mask(&pdev->dev, DMA_BIT_MASK(tdev->func->iommu_bit));
+	if (ret)
+		return ret;
 	ret = nvkm_device_tegra_power_up(tdev);