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SubjectRe: [PATCH] mass storage : emulation of sat scsi_pass_thru with ATACB
Matthew Dharm wrote:
> On Sat, Mar 08, 2008 at 09:08:26PM +0100, matthieu castet wrote:
>> Hi Matthew,
>>
>> thanks for your comments
>>
>> Matthew Dharm wrote:
>>> Why are you using an initializer instead of a new protocol code?
>> Because using a new protocol code means I need to patch all the place
>> where there is a comparison between us->subclass and US_SC_SCSI.
>> After all I am US_SC_SCSI with a special case for ATA12 & ATA16 commands.
>> I don't translate all scsi to atacb (that's what does US_SC_ISD200).
>
> Yet, you call invoke_transport directly, just like any other protocol
> handler.
>
> The proper way to do this is as a separate protocol handler. If you want
> to make it clear that you are only intercepting a couple of command types,
> then don't call invoke_transport() directly, call the transparent scsi
> protocol handler (which, of course, does the same thing but provides
> clearer layering).
>
> Oh, and you should add some "unlikely" tags to these if() conditionals.
Hum, may be to avoid confusion with a new protocol handler, I can add my
hook in usb_stor_control_thread with a new flag.

Something like :
[...]
/* Handle those devices which need us to fake
* their inquiry data */
else if ((us->srb->cmnd[0] == INQUIRY) &&
(us->flags & US_FL_FIX_INQUIRY)) {
[...]
else if (( (us->srb->cmnd[0] == ATA_12) || (us->srb->cmnd[0] == ATA_16)) &&
(us->flags & US_FL_CYPRESS_ATACB)) {
US_DEBUGP("emulating ATA pass thru\n");
call to emulate_pass_thru_with_atacb code
}

/* we've got a command, let's do it! */
else {
US_DEBUG(usb_stor_show_command(us->srb));
us->proto_handler(us->srb, us);
}

Does it sound better ?

Matthieu


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