[U-Boot] [PATCH] dm: core: don't fail to iterate if first one fails to probe

[Rob Clark]

On Thu, Aug 3, 2017 at 11:24 AM, Simon Glass <sjg at chromium.org> wrote:
> Hi Rob,
>
> On 19 July 2017 at 10:53, Rob Clark <robdclark at gmail.com> wrote:
>> On Thu, Jul 13, 2017 at 3:10 PM, Simon Glass <sjg at chromium.org> wrote:
>>> Hi Rob,
>>>
>>> On 21 June 2017 at 04:52, Rob Clark <robdclark at gmail.com> wrote:
>>>> On Wed, Jun 21, 2017 at 6:23 AM, Peter Robinson <pbrobinson at gmail.com> wrote:
>>>>> On Tue, Jun 20, 2017 at 10:49 PM, Rob Clark <robdclark at gmail.com> wrote:
>>>>>> efi_disk_register() would try to iterate all the blk devices.  But if
>>>>>> the first one in the list failed to probe, uclass_first_device() would
>>>>>> return NULL and no attempt would be made to register the remaining
>>>>>> devices.  Also uclass_next_device() needs the same fix.
>>>>>
>>>>> This looks related/similar to the "efi_loader: disk: iterate only over
>>>>> valid block devices" patch [1]
>>>>>
>>>>
>>>> hmm, I don't see uclass_first_device_check() which I guess must be
>>>> part of another in-flight patch?  I don't mind too much *how* we fix
>>>> it, as long as it works.  (Although it seems more sensible to just
>>>> make uclass_first_device()/etc dtrt rather than introducing another
>>>> function that actually works properly.. but that is only my $0.02)
>>>
>>> That patch is now in mainline. It was delayed for a release as I did
>>> not get any reviews and so wasn't sure if it was needed.
>>>
>>> I believe the common case is wanting to stop on error, since it means
>>> something is wrong. The case of continuing onto another device when
>>> the first one fails is unusual. We should always check return codes
>>> and return errors when something is wrong.
>>>
>>> I believe this case is happening because the device is removable and
>>> therefore returns an error. Is that right? If so then we should return
>>> a single error, such as -ENOMEDIUM so that the caller can ignore that
>>> error, or consider it OK.
>>
>> yes, iirc, the first one ended up being sd-card (which was removed)..
>> I'll have to check if driver is properly returning -ENOMEDIUM.  In
>> which case maybe the right thing to do is for the iterators skip over
>> just that single error code, since it isn't really an "unusual" error.
>
> OK that sounds better. Suppressing errors should be done with care.
>

fwiw, efi_loader in the mean time switched to
uclass_first_device_check().. so I guess we don't really need this
patch.  (I've dropped it for now since my stack of WIP patches is
pretty big already.)

BR,
-R