Re: AHCI driver preferring nr_ports over port map

[Tejun Heo <htejun@gmail.com>]

Jan Beulich wrote:
> Jeff,
> 
> while I realize that Intel's documentation may not be consistent with
> anything more generic (which I don't know where to look for), this
> current behavior seems to contradict what Intel documents for ESB2:
> 
> "23.3.1.4 PI – Ports Implemented Register (D31:F2)
> Address Offset: ABAR + 0Ch–0Fh Attribute: R/WO, RO
> Default Value: 00000000h Size: 32 bits
> 
> This register indicates which ports are exposed to the Intel®
> 631xESB/632xESB I/O Controller Hub. It is loaded by platform BIOS. It
> indicates which ports that the device supports are available for
> software to use. For ports that are not available, software must not
> read or write to registers within that port."

nr_ports is preferred over port_map when they disagree which shouldn't
happen in the first place.  On some earlier ahcis, PI was cleared to
zero and lower nr_port number of ports should be used.  The reason why
nr_ports is preferred over PI comes from similar place.  Hardware/BIOSen
are more likely to get PI wrong than nr_ports, so...

Do you have any real case where the above behavior causes problem?

-- 
tejun