Re: [PATCH] gpu: nova-core: fix three clippy::precedence warnings

[John Hubbard]

On 4/3/26 10:45 PM, Alexandre Courbot wrote:
> On Sat Apr 4, 2026 at 11:58 AM JST, John Hubbard wrote:
> > Clippy warns when shifts and bitwise-OR are mixed without parentheses,
> > because the relative precedence of << and | is easy to misread. This was
> > causing 3 warnings in drm-rust-next.
>
> These don't manifest for me (rustc 1.94.1), can you share more about the
> build context?

rustc 1.85.0

> > For read_sysmem_flush_page_ga100(), add explicit parentheses.
> >
> > For the PCI ROM header parsing, replace the manual byte-shifting with
> > u32::from_le_bytes(), which both fixes the warning and is clearer about
> > the intended byte order.
> >
> > Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
> > ---
> >   drivers/gpu/nova-core/fb/hal/ga100.rs | 7 ++++---
> >   drivers/gpu/nova-core/vbios.rs        | 7 +------
> >   2 files changed, 5 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/gpu/nova-core/fb/hal/ga100.rs b/drivers/gpu/nova-core/fb/hal/ga100.rs
> > index 1c03783cddef..b5d0f04198f0 100644
> > --- a/drivers/gpu/nova-core/fb/hal/ga100.rs
> > +++ b/drivers/gpu/nova-core/fb/hal/ga100.rs
> > @@ -17,9 +17,10 @@
> >   struct Ga100;
> >   
> >   pub(super) fn read_sysmem_flush_page_ga100(bar: &Bar0) -> u64 {
> > -    u64::from(bar.read(regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR).adr_39_08()) << FLUSH_SYSMEM_ADDR_SHIFT
> > -        | u64::from(bar.read(regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR_HI).adr_63_40())
> > -            << FLUSH_SYSMEM_ADDR_SHIFT_HI
> > +    (u64::from(bar.read(regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR).adr_39_08())
> > +        << FLUSH_SYSMEM_ADDR_SHIFT)
> > +        | (u64::from(bar.read(regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR_HI).adr_63_40())
> > +            << FLUSH_SYSMEM_ADDR_SHIFT_HI)
> >   }
> >   
> >   pub(super) fn write_sysmem_flush_page_ga100(bar: &Bar0, addr: u64) {
> > diff --git a/drivers/gpu/nova-core/vbios.rs b/drivers/gpu/nova-core/vbios.rs
> > index 3e3fa5b72524..ebda28e596c5 100644
> > --- a/drivers/gpu/nova-core/vbios.rs
> > +++ b/drivers/gpu/nova-core/vbios.rs
> > @@ -507,12 +507,7 @@ fn new(dev: &device::Device, data: &[u8]) -> Result<Self> {
> >   
> >           if data.len() >= 30 {
> >               // Read size_of_block at offset 0x1A.
> > -            size_of_block = Some(
> > -                u32::from(data[29]) << 24
> > -                    | u32::from(data[28]) << 16
> > -                    | u32::from(data[27]) << 8
> > -                    | u32::from(data[26]),
> > -            );
> > +            size_of_block = Some(u32::from_le_bytes([data[26], data[27], data[28], data[29]]));
>
> This chunk looks like it should be its own patch as it is valuable
> regardless of the clippy warnings.

OK.

thanks,
--
John Hubbard