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

[Marek Vasut]

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 ?

-- 
Best regards,
Marek Vasut