Re: [PATCH] sata_uli: ignore SIMPLEX

[Jeff Garzik <jgarzik@pobox.com>]

Tejun Heo wrote:
> Jeff Garzik wrote:
>> Tejun Heo wrote:
>>> Some uli controllers have stuck SIMPLEX bit which can't be cleared
>>> with ata_pci_clear_simplex(), but the controller is capable of doing
>>> DMAs on both channels simultaneously.  Ignore it.
>>>
>>> Signed-off-by: Tejun Heo <htejun@gmail.com>
>> This is going to be the common case going forward.  Please create an
>> 'ignore simplex bit' flag, and set it in sata_uli
> 
> I'm a little bit hesitant to do that.
> 
> 1. I don't think we're gonna have a lot of drivers which need this.
> Just a few.  We've just found one now.
> 
> 2. I think libata core layer (sff included) is burdened with too much
> already.  Also, now that devres is acked, we can easily transition to
> alloc - init - register model which gives LLDs much more flexibility and
> this kind of stuff can easily be done in init_one()'s.  It just fits there.

We need to correct a false assumption in the core.

The PCI IDE spec specifies the simplex bit, but a /vast majority/ of 
controllers, PATA as well as SATA, hardwire the bit, or program it to a 
value set by BIOS.  As such, most drivers really should /just know/ that 
their hardware need never worry about this odd simplex concept.

	Jeff