Re: [RFC PATCH] RFC: Sketch of dm event notification

Simon Glass
2021-11-17T02:50:03Z

Hi Takahiro,

On Tue, 16 Nov 2021 at 19:31, AKASHI Takahiro
<takahiro.akashi@linaro.org> wrote:
>
> Simon,
>
> On Mon, Nov 01, 2021 at 03:41:50PM +0900, AKASHI Takahiro wrote:
> > Hello Simon,
> >
> > On Sun, Oct 31, 2021 at 09:07:01PM -0600, Simon Glass wrote:
> > > This is a patch for Takahiro to look at, just for illustration. Not ready
> > > for review.
> >
> > Thank you for posting the draft.
> > At a first glance, it looks good and I don't see any specific issue
> > with your implementation.
>
> I said OK and functionally it should work well, but I now have
> some concerns:
> 1) In my current implementation, I use post_probe/pre_remove hooks
> of BLK device to invoke efi callback functions. In this sense,
> event(POST_PROBE/ PRE_REMOVE) seems to be a duplicated feature
> in some way.

We should not be calling EFI functions from a BLK devince, unless it
is an EFI block device, i.e. we should provide hooks for EFI or any
other interested party to use.

> 2) For the rest of uclass devices which don't utilise events yet,
> device_notify() is nothing but an overhead as it always tries to
> go through a list of event hooks.

Yes that's true, but it can be optimised to avoid useless
searches/calls, since subscribers need to specify an even they are
interested in.

>
> Event notification can be more than just a dm feature, but ...
> What's your thought here?

Yes, more than just a DM feature. For example I think it could help
with the initcalls we have in board_f and board_r.

Regards,
Simon

>
> -Takahiro Akashi
>
> > Since my code has already added DM_TAG support, I'm looking forward for
> > getting your final patch.
> >
> > The only remaining issue is *modeling* partitions :)
> >
> > -Takahiro Akashi
> >
> > > To run the test:
> > >
> > > ./u-boot -T -c "ut common test_event_probe"
> > >
> > > Signed-off-by: Simon Glass <sjg@chromium.org>
> > > ---

[..]

Regards,
Simon