Re: [PATCH #upstream-fixes] libata: disable ATAPI AN by default

[Robert Hancock <hancockrwd@gmail.com>]

On 05/19/2010 10:53 AM, Tejun Heo wrote:
> Hello,
>
> On 05/19/2010 06:14 PM, Jeff Garzik wrote:
>> Windows completely disables AN?
>>
>> Or do we simply need to be less naive about _delivery_ of AN's?
>
> I think we first need to verify what the event is about before
> delivering it to userland; IOW, it should kick a full polling op.  The
> problem is the same with periodic polling.  Windows does it with
> single command but we can't do that from userland as open() involves
> issuing more commands.  That discrepancy is basically we're having all
> these problems with periodic polling and AN infinite looping.
>
> Hardware vendors don't consider cases where their devices are hit with
> a series of commands periodically or after raising an AN event.  We
> have quite a few drives which just die after being hit repeatedly with
> media presence polling commands and this one is causing infinite loop
> by re-raising AN.
>
> So, until we can replicate the windows behavior (which actually is
> pretty reasonable - just use single GET_CONFIGURATION call for polling
> and status check), I think it's wiser to disable AN.

There are also some drives where AN is just broken - I have a Lite-ON 
DH-401S BD-ROM drive which raises AN on opening the tray, but not on 
closing with media inserted.

I don't know if Windows is using AN at all yet or not. Seems like a lot 
of drives aren't tested well with it though.