Re: [RFC/PATCH] IDE Power Management try 1

[Jens Axboe <axboe@suse.de>]

On Fri, Apr 25 2003, Alexander Atanasov wrote:
> 		Hello,
> 
> Benjamin Herrenschmidt wrote:
> 
> 
> >The point is to pipe the power management requests through the request
> >queue for proper locking. Since those requests involve several
> >operations that have to be tied together with the queue beeing locked
> >for further 'user' requests, they are implemented as a state machine
> >with specific callbacks in the subdrivers
> >
> [cut]
> >
> >One thing that should probably be cleaned up is the difference between
> >the suspend and the resume request. I didn't want to implement 2
> >different request bits to avoid using too much of that bit-space, and
> >because most of the core handling is the same. So right now, I carry in
> >the special structure attached to the request, 2 fields. An int
> >indicating if we are doing a suspend or a resume op, and an int that is
> >the actual state machine step.
> 
> > ===== include/linux/blkdev.h 1.100 vs edited =====
> > --- 1.100/include/linux/blkdev.h	Sun Apr 20 18:20:10 2003
> > +++ edited/include/linux/blkdev.h	Thu Apr 24 14:30:50 2003
> > @@ -116,6 +116,7 @@
> >  	__REQ_DRIVE_CMD,
> >  	__REQ_DRIVE_TASK,
> >  	__REQ_DRIVE_TASKFILE,
> > +	__REQ_POWER_MANAGEMENT,
> >  	__REQ_NR_BITS,	/* stops here */
> >  };
> 
> 
> 		What about this - add __REQ_DRIVE_INTERNAL, and carry args 
> 		in rq->cmd[16] [0] = PM, [1] = SUSPEND/RESUME, [2]= STATE ? IDE can use it 
> for power managment, error handling (do not do it from interrupt 
> context, but queue it), may be more. This way it would really makes 
> things a bit better with the complicated IDE locking. SCSI and probably 
> other block devices can benefit from this internal requests too, so the 
> bit is not wasted.

There are already lots of "INTERNAL" - basically take your pick from all
the ones you quote above (DRIVE_TASK, DRIVE_CMD, DRIVE_TASKFILE - it's a
MESS). A power management special request makes sense to me.

-- 
Jens Axboe