gpu: nvgpu: Set DMA mask on a per-platform basis

Each GPU platform has different DMA limitations. For older
chips the maximum size of a DMA buffer was more limited than
newer SoCs (read: Xavier) and discrete GPUs.

This patch adds support to set the DMA mask for a GPU on a
per platform basis by adding a platform field that is populated
with the maximum allowed DMA mask. That mask is programmed by
the driver common code. If no mask is specified then the
default mask size is 16GB (34 bits).

Bug 2043276

Change-Id: I9c3c76c86bac6c485eb1197326e662516fbcaa41
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1700980
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 9 insertions, 3 deletions

diff --git a/drivers/gpu/nvgpu/common/linux/driver_common.c b/drivers/gpu/nvgpu/common/linux/driver_common.c
index 8086cb29..015046dd 100644
--- a/drivers/gpu/nvgpu/common/linux/driver_common.c
+++ b/drivers/gpu/nvgpu/common/linux/driver_common.c
@@ -73,9 +73,15 @@ static void nvgpu_init_vars(struct gk20a *g)
         dev->dma_parms = &l->dma_parms;
         dma_set_max_seg_size(dev, UINT_MAX);
 
-        /* 34 bit mask - can be expanded for later chips is needed. */
-        dma_set_mask(dev, DMA_BIT_MASK(34));
-        dma_set_coherent_mask(dev, DMA_BIT_MASK(34));
+        /*
+         * A default of 16GB is the largest supported DMA size that is
+         * acceptable to all currently supported Tegra SoCs.
+         */
+        if (!platform->dma_mask)
+                platform->dma_mask = DMA_BIT_MASK(34);
+
+        dma_set_mask(dev, platform->dma_mask);
+        dma_set_coherent_mask(dev, platform->dma_mask);
 
         nvgpu_init_list_node(&g->profiler_objects);