Re: [PATCH] ide/libata: fix ata_id_is_cfa()

[Sergei Shtylyov <sshtylyov@ru.mvista.com>]

Hello, I wrote:

>> I shall draw the obvious conclusion from the fact you don't feel like 
>> providing one

>> The logic is this

>> ATA-3 or higher - that word has a defined meaning
>> ATA < 3 that word should be 0x0000
>> pre ATA (EIDE) or head up backside implementations that would will be
>> anything but usually 0x0000 or 0xFFFF

>> We cannot test for ATA < 3 because there is no version bit for it

>    That's not quite true, read the ATA-3 standard better.

>> Therefore we want to check

>>     CFA signature -> CFA (good for CFA 1.1 and later devices using it)
>>     ATA >= 3 claimed - word is trustable bit is 0 or means CFA

>    The problem is that the CF specs explicitly forbid (!) to report 
> anything in word 80 -- it's reserved and must be 0.
> 
>> Yes the implementation is paranoid, but having done ten years working for
>> a distro dealing with PC hardware in volume day in and day out I've yet

>    Working while checking word 82 ISO word 83? Who are you trying to cheat?

    I'm sorry, that was totally off base. I've misread this whole paragraph in 
haste. :-<
    The rest of my evening was wasted, sigh.

MBR, Sergei