Re: Proposed changes for libata speed handling

[Tejun Heo <htejun@gmail.com>]

Alan wrote:
> I'm currently hacking on the speed handling code a bit
> 
> I'd like to do the following unless anyone has any objections
> 
> - Remove post_set_mode and make drivers wrap the guts of the existing
> set_mode() function. This allows a driver to wrap and see success/failure
> while removing a callback, and also to add pre-mode code. (ie you'd do
> 
> foo_set_mode() {
>     ata_default_set_mode()
>     my_fiddling();
> }
> 
> - Fix the ->set_mode method FIXMEs in the current tree [DONE]
> 
> - Add set_specific_mode, with a default behaviour that works for most
> controllers. Those using a private ->set_mode might need a private
> ->set_specific_mode, in some cases like it8212 simply to error the request
> 
> - Hook set_specific_mode to the ata command parser so that instead of
> erroring set_features commands we snoop them and force the mode change
> desired on the controller (if valid)
> 
> - Send the command to set the speed before setting the controller speed,
> so that we send them at the right rate.
> 
> Any comments ?

Wouldn't it be better to have ->determine_xfer_mask() and
->set_specific_mode() than having two somewhat overlapping callbacks?
Or is there some problem that can't be handled that way?

Thanks.

-- 
tejun