Tejun Heo wrote:
AHCI uses CAP.NP to indicate the number of ports and PI to tell which ports are enabled. The only requirement is that the number of ports indicated by CAP.NP should equal or be higher than the number of enabled ports in PI. CAP.NP and PI carry duplicate information and there have been some interesting cases. Some early AHCI controllers didn't set PI at all and just implement from port 0 to CAP.NP. An ICH8 board which wired four out of six available ports had 3 (4 ports) for CAP.NP and 0x33 for PI. While ESB2 has less bits set in PI than the value in CAP.NP. Till now, ahci driver assumed that PI is invalid if it doesn't match CAP.NP exactly. This violates AHCI standard and the driver ends up accessing unmimplemented ports on ESB2. This patch updates CAP.NP and PI handling such that PI can have less number of bits set than indicated in CAP.NP and the highest port is determined as the maximum port of what CAP.NP and PI indicate. Signed-off-by: Tejun Heo <htejun@xxxxxxxxx> Cc: Jan Beulich <jbeulich@xxxxxxxxxx>
applied - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
