gpu: nova-core: falcon: align DMA transfers to 256 bytes

Falcon DMA transfers are done in 256 bytes increments, and the method
responsible for initiating the transfer checked that the required length
was indeed a multiple of 256. While correct, this also requires callers
to specifically account for this limitation of DMA transfers, and we had
for instance the fwsec code performing a seemingly arbitrary (and
potentially overflowing) upwards alignment of the DMEM load size to
match this requirement.

Let's move that alignment into the loading code itself instead: since it
is working in terms of number of transfers, we can turn this upwards
alignment into a non-overflowing operation, and check that the requested
transfer remains into the limits of the DMA object. This also allows us
to remove a DMA-specific constant in the fwsec code.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Link: https://lore.kernel.org/r/20250821-falcondma_256b-v2-1-83e8647a24b5@nvidia.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

1 files changed, 1 insertions, 8 deletions

diff --git a/drivers/gpu/nova-core/firmware/fwsec.rs b/drivers/gpu/nova-core/firmware/fwsec.rs
index 0dff3cfa90af..47f5e4524072 100644
--- a/drivers/gpu/nova-core/firmware/fwsec.rs
+++ b/drivers/gpu/nova-core/firmware/fwsec.rs
@@ -202,9 +202,6 @@ pub(crate) struct FwsecFirmware {
     ucode: FirmwareDmaObject<Self, Signed>,
 }
 
-// We need to load full DMEM pages.
-const DMEM_LOAD_SIZE_ALIGN: u32 = 256;
-
 impl FalconLoadParams for FwsecFirmware {
     fn imem_load_params(&self) -> FalconLoadTarget {
         FalconLoadTarget {
@@ -218,11 +215,7 @@ impl FalconLoadParams for FwsecFirmware {
         FalconLoadTarget {
             src_start: self.desc.imem_load_size,
             dst_start: self.desc.dmem_phys_base,
-            // TODO[NUMM]: replace with `align_up` once it lands.
-            len: self
-                .desc
-                .dmem_load_size
-                .next_multiple_of(DMEM_LOAD_SIZE_ALIGN),
+            len: self.desc.dmem_load_size,
         }
     }