[U-Boot] [PATCH v2 2/3] efi_loader: enumerate disk devices every time

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

Alex,

On Wed, Jan 23, 2019 at 10:51:29AM +0100, Alexander Graf wrote:
> On 01/22/2019 08:39 PM, Simon Glass wrote:
> >Hi Alex,
> >
> >On Tue, 22 Jan 2019 at 22:08, Alexander Graf <agraf@suse.de> wrote:
> >>
> >>
> >>On 22.01.19 09:29, AKASHI Takahiro wrote:
> >>>Alex, Simon,
> >>>
> >>>Apologies for my slow response on this matter,
> >>>
> >>>On Fri, Jan 11, 2019 at 08:57:05AM +0100, Alexander Graf wrote:
> >>>>
> >>>>On 11.01.19 05:29, AKASHI Takahiro wrote:
> >>>>>Alex, Heinrich and Simon,
> >>>>>
> >>>>>Thank you for your comments, they are all valuable but also make me
> >>>>>confused as different people have different requirements :)
> >>>>>I'm not sure that all of us share the same *ultimate* goal here.
> >>>>The shared ultimate goal is to "merge" (as Simon put it) dm and efi objects.
> >>>I don't still understand what "merge" means very well.
> >>It basically means that "struct efi_object" moves into "struct udevice".
> >>Every udevice instance of type UCLASS_BLK would expose the block and
> >>device_path protocols.
> >>
> >>This will be a slightly bigger rework, but eventually allows us to
> >>basically get rid of efi_init_obj_list() I think.
> >I envisaged something like:
> >
> >- EFI objects have their own UCLASS_EFI uclass
> 
> ... and then we need to create our own sub object model around the
> UCLASS_EFI devices again. I' not convinced that's a great idea yet :). I
> really see little reason not to just expose every dm device as EFI handle.
> Things would plug in quite naturally I think.

You said that the ultimate goal is to remove all efi_object data.
Do you think that all the existing efi_object can be mapped to
one of existing u-boot uclass devices?

If so, what would be an real entity of a UEFI handle?
struct udevice *?

But Simon seems not to agree to adding any UEFI-specific members
in struct udevice.

> But either way, someone would need to sit down and prototype things to be
> sure.
> 

The most simplest prototype would include
* event mechanism (just registration and execution of hook/handler)
    event: udevice creation (and deletion)
* efi_disk hook for udevice(UCLASS_BLK) creation
* modified block device's enumeration code, say, scsi_scan(),
  to add an event hook at udevice creation
* removing efi_disk_register() from efi_init_obj_list()
* Optionally(?) UCLASS_PARTITION
  (Partition udevices would be created in part_init().)

?

Thanks,
-Takahiro Akashi
> 
> Alex
>