Re: use_10_for_ms revisited?

[Jeff Garzik <jgarzik@pobox.com>]

Matthew Dharm wrote:
> Right now, we can handle this case with a slave_configure() function that
> sets use_10_for_ms and use_10_for_rw, like usb-storage does now.  The
> heuristic code in usb-storage is on the way out, once sr.c is converted (in
> progress).
> 
> Devices easily identified, heuristics gone, repeated code very minimal (2
> lines) -- sounds like a winner to me.  Actually, I have a feeling that any
> algorithm to try to determine MMC or not (complete with it's own heuristic
> to handle strange devices) will be much longer than those repeated 2 lines.

No argument, I'm sold :)  Sounds like a good plan.

That still doesn't address the issue use_10_for_ms being _too_ 
fine-grained, though:  mode sense is but one part of the larger picture.

We will still have duplicated ATAPI (and other?) logic in USB storage, 
ide-scsi, my driver, and elsewhere for items which are common to MMC. 
For many cases, it is silly to set a whole list of use_10_for_foo 
variables, when they are all unconditionally set to 1 when MMC is 
detected (->slave_configure).

So, a concrete suggestion would be:

Create 'mmc' bit for each scsi_device, set at slave_configure time. 
use_10_for_foo and other code can derive values from this.  i.e. provide 
enough information that can automatically set all those use_10_for_foo 
variables.

	Jeff