[U-Boot] [PATCH v6] cmd: usb: ignore blk, emulation devices in usb tree/info display

[Bin Meng]

Hi Marek,

On Thu, Oct 19, 2017 at 5:47 PM, Marek Vasut <marex at denx.de> wrote:
> On 10/19/2017 10:56 AM, Bin Meng wrote:
>> Hi Marek,
>>
>> On Thu, Oct 19, 2017 at 4:43 PM, Marek Vasut <marex at denx.de> wrote:
>>> On 10/19/2017 10:37 AM, Bin Meng wrote:
>>>> Hi Marek,
>>>
>>> Hi,
>>>
>>>> On Thu, Oct 19, 2017 at 3:33 PM, Marek Vasut <marex at denx.de> wrote:
>>>>> On 10/19/2017 05:24 AM, Suneel Garapati wrote:
>>>>>> On Wed, Oct 18, 2017 at 6:39 PM, Marek Vasut <marex at denx.de> wrote:
>>>>>>> On 10/19/2017 03:22 AM, Suneel Garapati wrote:
>>>>>>>> usb tree/info commands iterate over all usb uclass devices
>>>>>>>> recursively. blk uclass child devices are created for mass storage,
>>>>>>>> treating these as usb uclass devices and referencing usb config
>>>>>>>> interface descriptors cause crash. To fix, ignore blk and usb_emul
>>>>>>>> uclass devices(sandbox)
>>>>>>>                  ^^^^^^^ what's this about ? USB_EMUL devices can be
>>>>>>> enables elsewhere too, right ?
>>>>>> Only disabled during the tree/info dump.
>>>>>
>>>>> I don't understand this answer. Can USB_EMUL devices be enabled on any
>>>>> other machine than sandbox or not ? I presume it can ...
>>>>>
>>>>
>>>> No, it cannot.
>>>
>>> Why ? Because of the Kconfig thing ? That can easily change and then
>>> this breaks ...
>>
>> Yes, it's currently on on Sandbox. But whether it's on Sandbox or not
>> does not matter. These devices are should be filtered out as they are
>> not supposed to be on the USB topology.
>
> I agree with that, I was just commenting on this "(sandbox)" in the
> description, which IMO is not precise.
>
>>>>>>> Anyway, shouldn't you rather filter for positive matches (usb uclass
>>>>>>> devices etc) , rather than filtering out a few negative matches (blk
>>>>>>> etc) which might break in the future ?
>>>>>> usb_for_each_root_dev does that but we dont have uclass_find_first_child_device
>>>>>> to call on UCLASS_USB like uclass_find_first_device.
>>>>>> So, device_find_first_child and check on uclass id is performed.
>>>>>
>>>>> I mean, rather than doing
>>>>> (device_get_uclass_id(child) != UCLASS_USB_xxx &&
>>>>> device_get_uclass_id(child) != UCLASS_USB_yyy)
>>>>>    dump
>>>>>
>>>>> do
>>>>>
>>>>> (device_get_uclass_id(child) == UCLASS_USB_nnn)
>>>>>    dump
>>>>>
>>>>> for nnn being only the relevant USB classes for which we actually want
>>>>> to dump.
>>>>>
>>>>> Does that work ?
>>>>>
>>>>
>>>> No, I don't think you can enumerate all USB devices here. It can be
>>>> any uclass device.
>>>
>>> And only the blk one breaks things ?
>>
>> Yes, blk devices are not "struct usb_device" declared, as they are not
>> USB devices. However their parent is.
>
> In which case, _that_ should be in the commit message.
>
> Anyway, is there any chance something else will come in, ie. net device
> for USB ethernet devices ?
>

No problem with any USB devices that end up in the leaf node in the DM tree.

Regards,
Bin