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gpu: nova-core: falcon: pad firmware DMA object size to required block alignment

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Commit a88831502c ("gpu: nova-core: falcon: use dma::Coherent")
dropped the nova-local `DmaObject` device memory type for the
kernel-global `Coherent` one.

This switch had a side-effect: `DmaObject` always aligned the requested
size to `PAGE_SIZE`, and also reported that adjusted size when queried.
`Coherent`, on the other hand, does page-align allocation sizes but only
allows CPU access on the exact size provided by the caller.

This change runs into a limitation of falcon DMA copies, namely that DMA
accesses are done on blocks of exactly 256 bytes. If the provided data
does not have a length that is a multiple of 256, `dma_wr` returns
an error.

It was expected that all firmwares would present the proper adjusted
size, but this is not the case at least on my GA107:

    NovaCore 0000:08:00.0: DMA transfer goes beyond range of DMA object
    NovaCore 0000:08:00.0: Failed to load FWSEC firmware: EINVAL
    NovaCore 0000:08:00.0: probe with driver NovaCore failed with error -22

Fix this by padding the `Coherent`'s size to `MEM_BLOCK_ALIGNMENT` (i.e.
256) when allocating it and filling it with zeroes, before copying the
firmware on top of it.

Fixes: a88831502c ("gpu: nova-core: falcon: use dma::Coherent")
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Link: https://patch.msgid.link/20260405-falcon-dma-roundup-v2-1-4af5b2ff9c16@nvidia.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
This commit is contained in:
Alexandre Courbot
2026-04-05 11:22:54 +09:00
committed by Danilo Krummrich
parent 8e6c34785a
commit 0e0ffbcd0e
1 changed files with 19 additions and 2 deletions
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21
drivers/gpu/nova-core/falcon.rs
View File

@@ -11,6 +11,7 @@
},
dma::{
Coherent,
CoherentBox,
DmaAddress,
DmaMask, //
},
@@ -613,8 +614,24 @@ fn dma_load<F: FalconFirmware<Target = E> + FalconDmaLoadable>(
bar: &Bar0,
fw: &F,
) -> Result {
// Create DMA object with firmware content as the source of the DMA engine.
let dma_obj = Coherent::from_slice(dev, fw.as_slice(), GFP_KERNEL)?;
// DMA object with firmware content as the source of the DMA engine.
let dma_obj = {
let fw_slice = fw.as_slice();
// DMA copies are done in chunks of `MEM_BLOCK_ALIGNMENT`, so pad the length
// accordingly and fill with `0`.
let mut dma_obj = CoherentBox::zeroed_slice(
dev,
fw_slice.len().next_multiple_of(MEM_BLOCK_ALIGNMENT),
GFP_KERNEL,
)?;
// PANIC: `dma_obj` has been created with a length equal to or larger than
// `fw_slice.len()`, so the range `..fw_slice.len()` is valid.
dma_obj[..fw_slice.len()].copy_from_slice(fw_slice);
dma_obj.into()
};
self.dma_reset(bar);
bar.update(regs::NV_PFALCON_FBIF_TRANSCFG::of::<E>().at(0), |v| {