On 2/14/24 9:20 PM, Niklas Cassel wrote:
> We are currently printing the CAP.NP field.
> CAP.NP is a 0's based value indicating the maximum number of ports
> supported by the HBA silicon. Note that the number of ports indicated
> in this field may be more than the number of ports indicated in the
> PI (ports implemented) register. (See AHCI 1.3.1, section 3.1.1 -
> Offset 00h: CAP – HBA Capabilities.)
>
> Print the port_map instead, which is the value read by the PI (ports
> implemented) register (after fixups).
>
> PI (ports implemented) register is a field that has a bit set to '1'
> if that specific port is implemented. This register is allowed to have
> zeroes mixed with ones, i.e. a port in the middle is allowed to be
> unimplemented. (See AHCI 1.3.1, section 3.1.4 - Offset 0Ch: PI – Ports
> Implemented.)
>
> Fix the libata print to only print the number of implemented ports,
> instead of the theoretical number of ports supported by the HBA.
>
> Suggested-by: Damien Le Moal <dlemoal@xxxxxxxxxx>
> Signed-off-by: Niklas Cassel <cassel@xxxxxxxxxx>
> ---
> drivers/ata/ahci.h | 11 +++++++++++
> drivers/ata/libahci.c | 2 +-
> 2 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
> index df8f8a1a3a34..92d29a059763 100644
> --- a/drivers/ata/ahci.h
> +++ b/drivers/ata/ahci.h
> @@ -455,4 +455,15 @@ static inline int ahci_nr_ports(u32 cap)
> return (cap & 0x1f) + 1;
> }
>
> +static inline int ahci_nr_ports_in_map(u32 map)
> +{
> + unsigned long port_map = map;
Why cast to potentially 64-bit type?
> + int i, n = 0;
> +
> + for_each_set_bit(i, &port_map, AHCI_MAX_PORTS)
> + n++;
There's hweight32() for that, IIUC.
> +
> + return n;
> +}
> +
> #endif /* _AHCI_H */
[...]
MBR, Sergey
