[PATCH 1/2] dm: blk: assign media ID to block devices

[Simon Glass]

Hi Heinrich,

On Fri, 16 Sept 2022 at 00:41, Heinrich Schuchardt
<heinrich.schuchardt at canonical.com> wrote:
>
>
>
> On 9/16/22 03:30, Simon Glass wrote:
> > Hi Heinrich,
> >
> > On Thu, 15 Sept 2022 at 14:02, Heinrich Schuchardt
> > <heinrich.schuchardt at canonical.com> wrote:
> >>
> >> Currently block devices are only identified by uclass_id and device number.
> >> When dealing with removable media this is not enough to uniquely identify
> >> the medium.
> >>
> >> E.g. after host unbind, host bind we can have the same device number but a
> >> different backing file.
> >>
> >> The EFI specification uses a 32bit number media ID to identify media. Add a
> >> matching field to the block device descriptor.
> >>
> >> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> >> ---
> >>   drivers/block/blk-uclass.c | 16 +++++++++++++++-
> >>   include/blk.h              | 11 +++++++++++
> >>   2 files changed, 26 insertions(+), 1 deletion(-)
> >
> > Shouldn't this be handled by connecting the  EFI data to its udevice.
> > I think Takahiro has been looking at this?
> >
> > NAK to any EFI fields in blk_desc, in any case
>
> The information that a medium has changed can only come from the DM
> layer. If for instance the SD-card is swapped, this is indicated by the
> card detector switch. USB also has a signal for media changes.
>
> What are your ideas how the DM layer shall indicate media changes?

It should send an event, e.g. EVT_MEDIA and subscribers can then do
what is needed.

Regards,
Simon