sct erc does not work with megaraid

[Bokhan Artem <aptem@ngs.ru>]

Hello!

I'm trying to get/set sctserc (SMART Command Transport Error Recovery 
Control) data from sata disk attached to lsi megaraid controller with 
smartmontools, but this function does not work.

I want to figure out: is this driver or firmware issue? May someone to 
help to fix this?

The issue can be described as follows:

The ATA PASS-THROUGH(16) implementation in the SAT layer of the megaraid 
driver or firmware does not return the ATA output registers if 
requested. This violates SAT standard (http://www.t10.org/drafts.htm#SAT).

Expected: If CK_COND (bit 5 of CDB[2]) is set, ATA PASS-THROUGH(16) 
(CDB[0] = 0x85) shall return a CHECK CONDITION even if the ATA command 
completed successfully, and return the ATA output registers in the sense 
data using ATA return descriptor format (descriptor code 0x09).

Observed: If CK_COND is set and the ATA command completed successfully, 
ATA PASS-THROUGH(16) does not return a CHECK CONDITION or the sense data 
does not contain an ATA return descriptor.

See also the smartmontools SAT implementation 
(http://sourceforge.net/apps/trac/smartmontools/browser/trunk/smartmontools/scsiata.cpp?rev=3258#L146) 
for further info.