Re: [PATCH] 2.5 ide 48-bit usage

[Jens Axboe <axboe@suse.de>]

On Thu, May 08 2003, Bartlomiej Zolnierkiewicz wrote:
> 
> On Thu, 8 May 2003, Jens Axboe wrote:
> 
> > n Thu, May 08 2003, Bartlomiej Zolnierkiewicz wrote:
> > > 	if (!hwif->rqsize)
> > > 		hwif->rqsize = hwif->addressing ? 65536 : 256;
> >
> > btw, you didn't get this right this time either :-)
> 
> It is right.
> hwif->addressing means hwif supports 48-bit

No it doesn't, that's what I keep saying:

static int probe_lba_addressing (ide_drive_t *drive, int arg)
{
        drive->addressing =  0;

        if (HWIF(drive)->addressing)
                return 0;

	...

so if hwif->addressing != 0, you will never allow 48-bit lba on any
units on this hardware interface. So the correct logic is:

	hwif->rqsize = hwif->addressing ? 256 : 65536;

as in the patch.

> hwif->rqsize means max rq size for _hwif_

Correct.

> > drive->addressing == 1, 48-bit is ok
> > hwif->addressing == 1, 48-bit is _not_ ok
> 
> And?
> Even if !drive->addressing, hwif->addressing can be 1,

If hwif->addressing == 1, drive->addressing will never be anything _but_
0.

> so hwif->rqsize can be 65536.

Wrong

> > below patch covers the lat change as well, boots and works on my router.
> 
> Patch still misses pdx202xx_old.c changes :-).

Which?

> Two new ones:
> - rq_lba48(rq) should check for rq->hard_* values

Doesn't matter. I actually only thought about dma, in which case it
doesn't matter because we never change sector or nr_sectors until after
we have called ide_dma_end. For pio, it's no more reliable with hard_*
than without. This is all for end_request context of course, at init
time it's all the same. Essentially, we _need_ the taskfile changes for
this to work. In that case we can limit rq_lba48() to init request time,
and set task->addressing and use that from then on.

> - after some thought, drop _all_ changes to ide_dump_status()
>   (we may hit error when rq->nr_sectors is already < 256)

Ditto, cannot be reliable without the taskfile changes.

I won't bother with anything new until the taskfile stuff is in.

-- 
Jens Axboe