[PATCH 1/1] blk: simplify blk_get_devnum_by_typename()

[Simon Glass]

Hi Heinrich,

On Mon, 25 Oct 2021 at 09:44, Heinrich Schuchardt
<heinrich.schuchardt at canonical.com> wrote:
>
> On 10/25/21 17:18, Simon Glass wrote:
> > Hi Heinrich,
> >
> > On Mon, 25 Oct 2021 at 02:00, Heinrich Schuchardt
> > <heinrich.schuchardt at canonical.com> wrote:
> >>
> >> On 10/25/21 09:54, Heinrich Schuchardt wrote:
> >>> On 10/24/21 21:54, Simon Glass wrote:
> >>>> Hi Heinrich,
> >>>>
> >>>> On Sat, 23 Oct 2021 at 08:06, Heinrich Schuchardt
> >>>> <heinrich.schuchardt at canonical.com> wrote:
> >>>>>
> >>>>> The block descriptor contains the if_type. There is no need to first
> >>>>> look
> >>>>> up the uclass for the if_type and then to check the parent device's
> >>>>> uclass
> >>>>> to know if the device has the correct if_type.
> >>>>>
> >>>>> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> >>>>> ---
> >>>>>    drivers/block/blk-uclass.c | 35 +----------------------------------
> >>>>>    1 file changed, 1 insertion(+), 34 deletions(-)
> >>>>
> >>>> This seems to be heading in the wrong direction though.
> >>>>
> >>>> The IF_TYPE should really go away and be replaced with the UCLASS ID,
> >>>> I think.
> >>>>
> >>>> At present we have lots of calls to blk_create_device_f() which
> >>>> specify the type. I think we should drop the IF_TYPE_.. arg to that
> >>>> function and have it figured out from the uclass, in the interim.
> >>>>
> >>>> But why do we need IF_TYPE now?
> >>>
> >>> I admit that this patch is just an intermediate step.
> >>>
> >>> We can replace IF_TYPE by ULASS ID once SPL block devices are always
> >>> using the driver model. Have we reached this point yet? I have not seen
> >>> drivers/block/blk_legacy.c being deleted.
> >>
> >> qemu_malta64, qemu_malta64el, qemu_malta, qemu_maltael are examples of
> >> defconfigs requiring drivers/block/blk_legacy.c
> >
> > Yes, we seem to have BLK on only for MMC and USB, but malta64 (for
> > example) uses IDE.
> >
> > The problem seems to be HAVE_BLOCK_DEVICE which should not be used.
> >
> > +Tom Rini
> >
> > Should we remove HAVE_BLOCK_DEVICE at this point, or make it depend on BROKEN?
> >
> >>
> >> Best regards
> >>
> >> Heinrich
> >>
> >>>
> >>> Removing if_type_uclass_id[] is anyway on the right path.
> >
> > Are you sure? Instead, could we use the uclass ID in more places?
>
> Yes, you want to get rid of if_type. This means the table will become
> obsolete.

Yes.

> Once the legacy drivers are removed we can replace all occurrences of
> if_type by uclass_id. That uclass_id we should not take from blk_desc
> but from udevice.

How do we get from a blk_desc to a udevice, though?

Could you instead look at moving from using blk_desc to using udevice?
If we had that, I think I can see your point with this patch. At
present, it looks like a backwards step because you are reducing the
usage of the uclass and in fact removing it altogether.

Can you see what I am getting at? Let's move towards migration
incrementally, not destroy the bridges we have built towards the goal.

Regards,
Simon