Re: [PATCH v4 13/20] gpu: nova-core: vbios: store PMU lookup entries in a KVVec

[John Hubbard <jhubbard@nvidia.com>]

On 5/18/26 7:55 PM, Eliot Courtney wrote:
> The current code copies the data into a KVec and parses it on demand. We
> can simplify the code by storing the parsed entries.
> 
> Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>
> ---
>  drivers/gpu/nova-core/vbios.rs | 56 ++++++++++++++----------------------------
>  1 file changed, 18 insertions(+), 38 deletions(-)

This is a nice improvement.

Reviewed-by: John Hubbard <jhubbard@nvidia.com>

thanks,
-- 
John Hubbard


> 
> diff --git a/drivers/gpu/nova-core/vbios.rs b/drivers/gpu/nova-core/vbios.rs
> index 987eb1948314..1ffaf0ef56a7 100644
> --- a/drivers/gpu/nova-core/vbios.rs
> +++ b/drivers/gpu/nova-core/vbios.rs
> @@ -917,8 +917,7 @@ unsafe impl FromBytes for PmuLookupTableHeader {}
>  /// The table of entries is pointed to by the falcon data pointer in the BIT table, and is used to
>  /// locate the Falcon Ucode.
>  struct PmuLookupTable {
> -    header: PmuLookupTableHeader,
> -    table_data: KVec<u8>,
> +    entries: KVVec<PmuLookupTableEntry>,
>  }
>  
>  impl PmuLookupTable {
> @@ -929,48 +928,29 @@ fn new(dev: &device::Device, data: &[u8]) -> Result<Self> {
>          let entry_len = usize::from(header.entry_len);
>          let entry_count = usize::from(header.entry_count);
>  
> -        let required_bytes = header_len + (entry_count * entry_len);
> +        let data = data
> +            .get(header_len..header_len + entry_count * entry_len)
> +            .ok_or(EINVAL)
> +            .inspect_err(|_| {
> +                dev_err!(dev, "PmuLookupTable data length less than required\n");
> +            })?;
>  
> -        if data.len() < required_bytes {
> -            dev_err!(dev, "PmuLookupTable data length less than required\n");
> -            return Err(EINVAL);
> +        let mut entries = KVVec::with_capacity(entry_count, GFP_KERNEL)?;
> +        for i in 0..entry_count {
> +            let (entry, _) = PmuLookupTableEntry::from_bytes_copy_prefix(&data[i * entry_len..])
> +                .ok_or(EINVAL)?;
> +            entries.push(entry, GFP_KERNEL)?;
>          }
>  
> -        // Create a copy of only the table data
> -        let table_data = {
> -            let mut ret = KVec::new();
> -            ret.extend_from_slice(&data[header_len..required_bytes], GFP_KERNEL)?;
> -            ret
> -        };
> -
> -        Ok(PmuLookupTable { header, table_data })
> -    }
> -
> -    fn lookup_index(&self, idx: u8) -> Result<PmuLookupTableEntry> {
> -        if idx >= self.header.entry_count {
> -            return Err(EINVAL);
> -        }
> -
> -        let index = (usize::from(idx)) * usize::from(self.header.entry_len);
> -        let (entry, _) = self
> -            .table_data
> -            .get(index..)
> -            .and_then(PmuLookupTableEntry::from_bytes_copy_prefix)
> -            .ok_or(EINVAL)?;
> -
> -        Ok(entry)
> +        Ok(PmuLookupTable { entries })
>      }
>  
>      // find entry by type value
> -    fn find_entry_by_type(&self, entry_type: u8) -> Result<PmuLookupTableEntry> {
> -        for i in 0..self.header.entry_count {
> -            let entry = self.lookup_index(i)?;
> -            if entry.application_id == entry_type {
> -                return Ok(entry);
> -            }
> -        }
> -
> -        Err(EINVAL)
> +    fn find_entry_by_type(&self, entry_type: u8) -> Result<&PmuLookupTableEntry> {
> +        self.entries
> +            .iter()
> +            .find(|entry| entry.application_id == entry_type)
> +            .ok_or(EINVAL)
>      }
>  }
>  
>