[PATCH v2 4/7] gpu: nova-core: use `try_from` instead of `as` for u32 conversions

[Alexandre Courbot <acourbot@nvidia.com>]

There are a few situations in the driver where we convert a `usize` into
a `u32` using `as`. Even though most of these are obviously correct, use
`try_from` and let the compiler optimize wherever it is safe to do so.

Acked-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
---
 drivers/gpu/nova-core/fb/hal/tu102.rs   | 16 +++++++---------
 drivers/gpu/nova-core/firmware/fwsec.rs |  8 ++++----
 2 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/nova-core/fb/hal/tu102.rs b/drivers/gpu/nova-core/fb/hal/tu102.rs
index b022c781caf4..32114c3b3686 100644
--- a/drivers/gpu/nova-core/fb/hal/tu102.rs
+++ b/drivers/gpu/nova-core/fb/hal/tu102.rs
@@ -15,15 +15,13 @@ pub(super) fn read_sysmem_flush_page_gm107(bar: &Bar0) -> u64 {
 
 pub(super) fn write_sysmem_flush_page_gm107(bar: &Bar0, addr: u64) -> Result {
     // Check that the address doesn't overflow the receiving 32-bit register.
-    if addr >> (u32::BITS + FLUSH_SYSMEM_ADDR_SHIFT) == 0 {
-        regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR::default()
-            .set_adr_39_08((addr >> FLUSH_SYSMEM_ADDR_SHIFT) as u32)
-            .write(bar);
-
-        Ok(())
-    } else {
-        Err(EINVAL)
-    }
+    u32::try_from(addr >> FLUSH_SYSMEM_ADDR_SHIFT)
+        .map_err(|_| EINVAL)
+        .map(|addr| {
+            regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR::default()
+                .set_adr_39_08(addr)
+                .write(bar)
+        })
 }
 
 pub(super) fn display_enabled_gm107(bar: &Bar0) -> bool {
diff --git a/drivers/gpu/nova-core/firmware/fwsec.rs b/drivers/gpu/nova-core/firmware/fwsec.rs
index dd3420aaa2bf..ce78c1563754 100644
--- a/drivers/gpu/nova-core/firmware/fwsec.rs
+++ b/drivers/gpu/nova-core/firmware/fwsec.rs
@@ -291,7 +291,7 @@ fn new_fwsec(dev: &Device<device::Bound>, bios: &Vbios, cmd: FwsecCommand) -> Re
 
             frts_cmd.read_vbios = ReadVbios {
                 ver: 1,
-                hdr: size_of::<ReadVbios>() as u32,
+                hdr: u32::try_from(size_of::<ReadVbios>())?,
                 addr: 0,
                 size: 0,
                 flags: 2,
@@ -304,9 +304,9 @@ fn new_fwsec(dev: &Device<device::Bound>, bios: &Vbios, cmd: FwsecCommand) -> Re
                 } => {
                     frts_cmd.frts_region = FrtsRegion {
                         ver: 1,
-                        hdr: size_of::<FrtsRegion>() as u32,
-                        addr: (frts_addr >> 12) as u32,
-                        size: (frts_size >> 12) as u32,
+                        hdr: u32::try_from(size_of::<FrtsRegion>())?,
+                        addr: u32::try_from(frts_addr >> 12)?,
+                        size: u32::try_from(frts_size >> 12)?,
                         ftype: NVFW_FRTS_CMD_REGION_TYPE_FB,
                     };
 

-- 
2.51.0