[PATCH 1/1] dm: fix blk_get_devnum_by_uclass_idname()
Simon Glass
sjg at chromium.org
Tue Oct 11 16:16:04 CEST 2022
Hi Heinrich,
On Tue, 11 Oct 2022 at 04:38, Heinrich Schuchardt
<heinrich.schuchardt at canonical.com> wrote:
>
>
>
> On 10/11/22 07:46, Heinrich Schuchardt wrote:
> >
> >
> > On 10/11/22 01:49, Simon Glass wrote:
> >> Hi Heinrich,
> >>
> >> On Thu, 6 Oct 2022 at 14:05, Heinrich Schuchardt
> >> <heinrich.schuchardt at canonical.com> wrote:
> >>>
> >>> On 10/3/22 18:44, Simon Glass wrote:
> >>>> Hi Heinrich,
> >>>>
> >>>> On Mon, 3 Oct 2022 at 10:33, Heinrich Schuchardt
> >>>> <heinrich.schuchardt at canonical.com> wrote:
> >>>>>
> >>>>>
> >>>>>
> >>>>> On 10/3/22 16:57, Simon Glass wrote:
> >>>>>> Hi Heinrich,
> >>>>>>
> >>>>>> On Mon, 3 Oct 2022 at 03:36, Heinrich Schuchardt
> >>>>>> <heinrich.schuchardt at canonical.com> wrote:
> >>>>>>>
> >>>>>>> On the sandbox I run:
> >>>>>>>
> >>>>>>> => setenv efi_selftest block device
> >>>>>>> => bootefi selftest
> >>>>>>>
> >>>>>>> and see the following output:
> >>>>>>>
> >>>>>>> ** Bad device specification host 0 **
> >>>>>>> Couldn't find partition host 0:0
> >>>>>>> Cannot read EFI system partition
> >>>>>>>
> >>>>>>> Running
> >>>>>>>
> >>>>>>> => lsblk
> >>>>>>>
> >>>>>>> yields
> >>>>>>>
> >>>>>>> Block Driver Devices
> >>>>>>> -----------------------------
> >>>>>>> efi_blk : efiloader 0
> >>>>>>> ide_blk : <none>
> >>>>>>> mmc_blk : mmc 2, mmc 1, mmc 0
> >>>>>>> nvme-blk : <none>
> >>>>>>> sandbox_host_blk : <none>
> >>>>>>> scsi_blk : <none>
> >>>>>>> usb_storage_blk : <none>
> >>>>>>> virtio-blk : <none>
> >>>>>>>
> >>>>>>> So a efi_blk device was mistaken for a host device.
> >>>>>>>
> >>>>>>> I continue with
> >>>>>>>
> >>>>>>> => host bind 0 ../sandbox.img
> >>>>>>> => ls host 0:1
> >>>>>>>
> >>>>>>> and get the following output:
> >>>>>>>
> >>>>>>> 13 hello.txt
> >>>>>>> 7 u-boot.txt
> >>>>>>>
> >>>>>>> 2 file(s), 0 dir(s)
> >>>>>>>
> >>>>>>> This is the content of efiblock 0:1 and not of host 0:1 (sic!).
> >>>>>>>
> >>>>>>> The uclass of the parent device is irrelevant for the
> >>>>>>> determination of the
> >>>>>>> uclass of the block device. We must use the uclass stored in the
> >>>>>>> block
> >>>>>>> device descriptor.
> >>>>>>>
> >>>>>>> This issue has been raised repeatedly:
> >>>>>>>
> >>>>>>> [PATCH 1/1] block: fix blk_get_devnum_by_typename()
> >>>>>>> https://lore.kernel.org/u-boot/20220802094933.69170-1-heinrich.schuchardt@canonical.com/
> >>>>>>> [PATCH 1/1] blk: simplify blk_get_devnum_by_typename()
> >>>>>>> https://lore.kernel.org/u-boot/20211023140647.7661-1-heinrich.schuchardt@canonical.com/
> >>>>>>
> >>>>>> Yes and you were not able/willing to take on the required work, so
> >>>>>> this carried on longer than it should have. I finally did this myself
> >>>>>> and it is now in -next.
> >>>>>
> >>>>> The refactoring was orthogonal to the problem that I reported and
> >>>>> which
> >>>>> you unfortunately did not consider in the process.
> >>>>
> >>>> Well it involved using if_type to work around a problem, just making
> >>>> it harder to get rid of. Overall I am in favour of a faster pace of
> >>>> migration that we have been following and it would help if people took
> >>>> on some of this, instead of fixing their little issue.
> >>>>
> >>>>>
> >>>>>>
> >>>>>> So we might finally be able to fix this problem properly, since
> >>>>>> if_type is mostly just a work-around concept in -next, with just the
> >>>>>> fake uclass_id being used at present.
> >>>>>>
> >>>>>> Can you use if_type_to_uclass_id() here, which is the work-around
> >>>>>> function for now?
> >>>>>
> >>>>> This function does not exist in origin/next. We won't apply this patch
> >>>>> in the 2022-10 cycle.
> >>>>
> >>>> I think I mean conv_uclass_id() which is the new name.
> >>>>
> >>>>>
> >>>>> Let's fix the bug first before thinking about future refactoring.
> >>>>>
> >>>>> You may determine the uclass ID for field bdev in struct blk_desc
> >>>>> using
> >>>>> function device_get_uclass_id() when refactoring.
> >>>>
> >>>> So if you call conv_uclass_id() (without any other refactoring) does
> >>>> that fix the problem?
> >>>
> >>> Except for UCLASS_USB that function is a NOP. How could it help to
> >>> differentiate between devices with the same parent device?
> >>
> >> It can't. But the root node should not have UCLASS_BLK children. I
> >> think I mentioned that a few months back?
> >>
> >>>
> >>> Would you agree that blk_get_devnum_by_uclass_idname() should not look
> >>> at the parent but on the actual device?
> >>
> >> No, looking at the parent is exactly what it should do. A block device
> >> is generic, to the extent possible. Its methods are implemented in the
> >> parent uclass and are tightly bound to it. See for example
> >> U_BOOT_DRIVER(mmc_blk) in the MMC uclass.
> >
> > Let's look at an MMC device
> >
> > root_driver/soc/mmc at 1c0f000/mmc at 1c0f000.blk is a block device.
> >
> > What do we need to find out that it can be addressed as mmc 0? The
> > driver is mmc_blk and its index is 0. We don't need any information
> > about the parent device at all.
If blk is the MMC block device, the fact that is mmc 0 is determined
by dev_seq(dev_get_parent(blk)). We are not parsing strings to find
that out. It is part of the design.
> >
> >>
> >> Unfortunately this confusion is my fault since I used the root device
> >> for the sandbox block devices. That was a convenience and a way to
> >> reduce somewhat the crushing load of driver model migration. But the
> >> time for that convenience is gone and we should create a sandbox host
> >> parent node for the sandbox block devices and tidy up EFI too.
> >
> > The only confusion is in the current blk_get_devnum_by_uclass_idname()
> > code looking into the parent device.
> >
> > The parent device is totally irrelevant here. Stop using it.
See below.
>
> You already noted when writing conv_uclass_id() that using the uclass
> name does not work properly to find out the CLI name of a devie.
>
> Can we put the CLI name for device types ("mmc", "scsi" ...) into struct
> blk_ops? Then we have a clear separation of the block device from the
> parent device.
There really isn't any separation in driver model...the parent device
does determine the type of the block device. It creates the block
device, using its own uclass. See for example mmc-uclass.c in
mmc_bind():
ret = blk_create_devicef(dev, "mmc_blk", "blk", UCLASS_MMC,
dev_seq(dev), 512, 0, &bdev);
The following fields in blk_desc will be dropped at some point:
- uclass_id since it is the same as the parent*
- bdev (point to block device) since we will stop passing around
blk_desc and will use the block device instead
- devnum since it is the save as dev_seq(blk)
* Except for the USB weirdness in conv_uclass_id() which we need to fix
Why do you want this 'separation'? Is this another strange EFI thing
due to it not using driver model properly?
Also you have not yet replied to my point about needing to create a
parent 'media' device for every block device. That is also part of the
design. Have you done that for EFI, or is your reluctance to do that
behind continued discussions and misalignments on UCLASS_BLK ?
Regards,
Simon
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