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

[John Hubbard <jhubbard@nvidia.com>]

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@nvidia.com>
>> ---
>>   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