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

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

Alex,

On Wed, Jan 09, 2019 at 10:06:16AM +0100, Alexander Graf wrote:
> 
> 
> On 13.12.18 08:58, AKASHI Takahiro wrote:
> > Heinrich,
> > 
> > On Tue, Dec 11, 2018 at 08:55:41PM +0100, Heinrich Schuchardt wrote:
> >> On 11/15/18 5:58 AM, AKASHI Takahiro wrote:
> >>> Currently, efi_init_obj_list() scan disk devices only once, and never
> >>> change a list of efi disk devices. This will possibly result in failing
> >>> to find a removable storage which may be added later on. See [1].
> >>>
> >>> In this patch, called is efi_disk_update() which is responsible for
> >>> re-scanning UCLASS_BLK devices and removing/adding efi disks if necessary.
> >>>
> >>> For example,
> >>>
> >>> => efishell devices
> >>> Scanning disk pci_mmc.blk...
> >>> Found 3 disks
> >>> Device Name
> >>> ============================================
> >>> /VenHw(e61d73b9-a384-4acc-aeab-82e828f3628b)
> >>> /VenHw(e61d73b9-a384-4acc-aeab-82e828f3628b)/SD(0)/SD(0)
> >>> /VenHw(e61d73b9-a384-4acc-aeab-82e828f3628b)/SD(0)/SD(0)/HD(2,MBR,0x086246ba,0x40800,0x3f800)
> >>> => usb start
> >>> starting USB...
> >>> USB0:   USB EHCI 1.00
> >>> scanning bus 0 for devices... 3 USB Device(s) found
> >>>        scanning usb for storage devices... 1 Storage Device(s) found
> >>> => efishell devices
> >>> Scanning disk usb_mass_storage.lun0...
> >>> Device Name
> >>> ============================================
> >>> /VenHw(e61d73b9-a384-4acc-aeab-82e828f3628b)
> >>> /VenHw(e61d73b9-a384-4acc-aeab-82e828f3628b)/SD(0)/SD(0)
> >>> /VenHw(e61d73b9-a384-4acc-aeab-82e828f3628b)/SD(0)/SD(0)/HD(2,MBR,0x086246ba,0x40800,0x3f800)
> >>> /VenHw(e61d73b9-a384-4acc-aeab-82e828f3628b)/USBClass(0,0,9,0,1)/USBClass(46f4,1,0,0,0)/HD(1,0x01,0,0x40,0x14fe4c)
> >>>
> >>> Without this patch, the last device, USB mass storage, won't show up.
> >>>
> >>> [1] https://lists.denx.de/pipermail/u-boot/2018-October/345307.html
> >>>
> >>> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> >>
> >> Why should we try to fix something in the EFI subsystems that goes wrong
> >> in the handling of device enumeration.
> > 
> > No.
> > This is a natural result from how efi disks are currently implemented on u-boot.
> > Do you want to totally re-write/re-implement efi disks?
> 
> Could we just make this event based for now? Call a hook from the
> storage dm subsystem when a new u-boot block device gets created to
> issue a sync of that in the efi subsystem?

If I correctly understand you, your suggestion here corresponds
with my proposal#3 in [1] while my current approach is #2.

[1] https://lists.denx.de/pipermail/u-boot/2018-October/345307.html

So we will call, say, efi_disk_create(struct udevice *) in
blk_create_device() and efi_dsik_delete() in blk_unbind_all().
UEFI handles for disks, however, will *not* be deleted actually
because, as Heinrich suggested in the past, no *reference count*
for a handle is maintained in the current implementation. Right?

> That hook would obviously only do something (or get registered?) when
> the efi object stack is initialized.
> 
> The long term goal IMHO should still be though to just merge DM and EFI
> objects. But we're still waiting on the deprecation of non-DM devices
> for that.

Maybe my #4?

-Takahiro Akashi

> 
> Alex