[U-Boot] [PATCH 07/16] usb: hub: Translate USB 3.0 hub port status into old version

[Bin Meng]

Hi Marek,

On Thu, Jun 29, 2017 at 1:25 AM, Marek Vasut <marex at denx.de> wrote:
> On 06/28/2017 10:28 AM, Bin Meng wrote:
>> Hi Marek,
>>
>> On Tue, Jun 27, 2017 at 7:57 AM, Bin Meng <bmeng.cn at gmail.com> wrote:
>>> Hi Marek,
>>>
>>> On Tue, Jun 27, 2017 at 2:06 AM, Marek Vasut <marex at denx.de> wrote:
>>>> On 06/24/2017 03:53 AM, Bin Meng wrote:
>>>>> Hi Marek,
>>>>>
>>>>> On Sat, Jun 24, 2017 at 1:59 AM, Marek Vasut <marex at denx.de> wrote:
>>>>>> On 06/23/2017 11:54 AM, Bin Meng wrote:
>>>>>>> USB 3.0 hub port status field has different bit positions from 2.0
>>>>>>> hubs. Since U-Boot only understands the old version, translate the
>>>>>>> new one into the old one.
>>>>>>
>>>>>> This is quite hairy. I'd rather see some protocol version agnostic flag
>>>>>> field rather than patching the wPortStatus and co.
>>>>>>
>>>>>
>>>>> I am not sure how do do that in a clean way. If we return the raw 3.0
>>>>> hub port status data, that means we need change lot of hub codes here
>>>>> and there to do different parsing.
>>>>
>>>> How does Linux handle this?
>>>
>>> Looks Linux is doing different parsing depending on hub is 3.0 or 2.0,
>>> at least for the power bit that I was just looking at. Do you want to
>>> do that?
>>
>> OK, I will do something similar like Linux in v2.
>
> Thanks

After I checked Linux codes in depth, it looks current way of handling
3.0 port status translation in this patch is the minimum way to fix
the 3.0 hub port status problem in U-Boot. What Linux does is, one
xHCI controller registers two buses, that one is USB 3.0 and the other
is USB 2.0. All 3.0 devices will only show on the 3.0 bus, while all
1.0/2.0 devices will show on the 2.0 bus. We can certainly do similar
thing in U-Boot, but I am afraid that will lead to a overhaul to
current USB stack and xHCI driver. And most important, that support
will be only under DM, which is something you don't like to see.

Regards,
Bin