Re: musb: communication issue with more than 12 FTDI ports

[Felipe Balbi <balbi-l0cyMroinI0@public.gmane.org>]

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Hi,

Bin Liu <b-liu-l0cyMroinI0@public.gmane.org> writes:
> Felipe,
>
> On 10/14/2015 11:25 AM, Felipe Balbi wrote:
>>
>> Hi,
>>
>> Bin Liu <b-liu-l0cyMroinI0@public.gmane.org> writes:
>>> On 10/14/2015 10:56 AM, Felipe Balbi wrote:
>>>>
>>>> Hi,
>>>>
>>>> Bin Liu <b-liu-l0cyMroinI0@public.gmane.org> writes:
>>>>> Hi,
>>>>>
>>>>> On 10/13/2015 01:22 PM, Felipe Balbi wrote:
>>>>>> Yegor Yefremov <yegorslists-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org> writes:
>>>>>>> On Mon, Oct 12, 2015 at 11:34 AM, Yegor Yefremov
>>>>>>> <yegorslists-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org> wrote:
>>>>>>>> We have a problem, when using more than 12 FTDI ports. Kernels tried:
>>>>>>>> 3.18.1, 4.2.3 and 4.3-rc5. SoC am335x 600MHz
>>>>>>>>
>>>>>>>> Below the USB topology:
>>>>>>>>
>>>>>>>> # lsusb -t
>>>>>>>> /:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=musb-hdrc/1p, 480M
>>>>>>>> /:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=musb-hdrc/1p, 480M
>>>>>>>>        |__ Port 1: Dev 2, If 0, Class=, Driver=hub/4p, 480M
>>>>>>>>            |__ Port 1: Dev 9, If 0, Class=, Driver=hub/4p, 480M
>>>>>>>>                |__ Port 1: Dev 10, If 0, Class=, Driver=ftdi_sio, 12M
>>>>>>>>                |__ Port 2: Dev 11, If 0, Class=, Driver=ftdi_sio, 480M
>>>>>>>>                |__ Port 2: Dev 11, If 1, Class=, Driver=ftdi_sio, 480M
>>>>>>>>                |__ Port 2: Dev 11, If 2, Class=, Driver=ftdi_sio, 480M
>>>>>>>>                |__ Port 2: Dev 11, If 3, Class=, Driver=ftdi_sio, 480M
>>>>>>>>                |__ Port 3: Dev 12, If 0, Class=, Driver=ftdi_sio, 480M
>>>>>>>>                |__ Port 3: Dev 12, If 1, Class=, Driver=ftdi_sio, 480M
>>>>>>>>                |__ Port 3: Dev 12, If 2, Class=, Driver=ftdi_sio, 480M
>>>>>>>>                |__ Port 3: Dev 12, If 3, Class=, Driver=ftdi_sio, 480M
>>>>>>>>            |__ Port 2: Dev 4, If 0, Class=, Driver=ftdi_sio, 480M
>>>>>>>>            |__ Port 2: Dev 4, If 1, Class=, Driver=ftdi_sio, 480M
>>>>>>>>            |__ Port 2: Dev 4, If 2, Class=, Driver=ftdi_sio, 480M
>>>>>>>>            |__ Port 2: Dev 4, If 3, Class=, Driver=ftdi_sio, 480M
>>>>>>>>            |__ Port 3: Dev 7, If 0, Class=, Driver=ftdi_sio, 480M
>>>>>>>>            |__ Port 3: Dev 7, If 1, Class=, Driver=ftdi_sio, 480M
>>>>>>>>            |__ Port 3: Dev 7, If 2, Class=, Driver=ftdi_sio, 480M
>>>>>>>>            |__ Port 3: Dev 7, If 3, Class=, Driver=ftdi_sio, 480M
>>>>>
>>>>> How many EPs does each FTDI device require? at least one INT EP, right?
>>>>> If I read it right, the topology above has 2 hubs, and 16 high-speed
>>>>> FTDI and 1 full-speed FTDI. So it requires at least 18 high-speed INT
>>>>> EPs. MUSB driver only has 11 high-speed EPs for mode-4 which is the EP
>>>>> configuration used by default. I am wondering how those devices got
>>>>> enumerated properly.
>>>>
>>>> dynamic EP allocation, but that has its own limitations.
>>>>
>>> MUSB does not support dynamic EP allocation for INT/ISOCH.
>>
>> I remember isoc doesn't, not sure about int. Do you remember where that
>> part of the code is off the top of your head ?
>>
>
> The MUSB EP allocation is in musb_schedule() in musb_host.c.
>
> It does not have specific policy for INT/ISOCH, but the issue is that 
> for periodic EP, it got allocated during device enumeration but freed 
> only when the device is disconnected. So practically there is no dynamic 
> EP allocation for INT/ISOCH.

This is not exactly what I can see when trying things out:

minicom.cap:56:[   90.909917] musb-hdrc musb-hdrc.1.auto: qh df62d240 urb dc4ebec0 dev3 ep1in-intr, hw_ep 10, df700680/1
minicom.cap:66:[   91.175860] musb-hdrc musb-hdrc.1.auto: qh df62d240 urb dc4ebec0 dev3 ep1in-intr, hw_ep 10, df700680/1
minicom.cap:100:[   91.697827] musb-hdrc musb-hdrc.1.auto: qh df62d240 urb dc4ebec0 dev3 ep1in-intr, hw_ep 10, df700680/1
minicom.cap:106:[   91.818066] musb-hdrc musb-hdrc.1.auto: qh dc4eb340 urb df5b7e40 dev4 ep1in-intr, hw_ep 11, df5c3400/1
minicom.cap:149:[   92.475792] musb-hdrc musb-hdrc.1.auto: qh df62d240 urb dc4ebec0 dev3 ep1in-intr, hw_ep 10, df700680/1
minicom.cap:162:[   92.736808] musb-hdrc musb-hdrc.1.auto: qh dc07d5c0 urb dc4ebec0 dev3 ep1in-intr, hw_ep 10, df700680/1
minicom.cap:207:[   93.703046] musb-hdrc musb-hdrc.1.auto: qh df551cc0 urb df65ee40 dev7 ep1in-intr, hw_ep 12, df6a2bc0/1
minicom.cap:215:[   93.977574] musb-hdrc musb-hdrc.1.auto: qh df551cc0 urb df65ee40 dev7 ep1in-intr, hw_ep 12, df6a2bc0/1
minicom.cap:240:[   94.388472] musb-hdrc musb-hdrc.1.auto: qh dc4eb340 urb df5b7e40 dev4 ep1in-intr, hw_ep 11, df5c3400/1
minicom.cap:289:[   95.422325] musb-hdrc musb-hdrc.1.auto: qh dc4eb340 urb df5b7e40 dev4 ep1in-intr, hw_ep 11, df5c3400/1
minicom.cap:305:[   95.688207] musb-hdrc musb-hdrc.1.auto: qh dc4eb340 urb df5b7e40 dev4 ep1in-intr, hw_ep 11, df5c3400/1
minicom.cap:335:[   96.291453] musb-hdrc musb-hdrc.1.auto: qh df551cc0 urb df65ee40 dev7 ep1in-intr, hw_ep 12, df6a2bc0/1
minicom.cap:410:[   97.696976] musb-hdrc musb-hdrc.1.auto: qh df6b70c0 urb dc011f40 dev11 ep1in-intr, hw_ep 2, dd842080/8
minicom.cap:56:[   90.909917] musb-hdrc musb-hdrc.1.auto: qh df62d240 urb dc4ebec0 dev3 ep1in-intr, hw_ep 10, df700680/1
minicom.cap:66:[   91.175860] musb-hdrc musb-hdrc.1.auto: qh df62d240 urb dc4ebec0 dev3 ep1in-intr, hw_ep 10, df700680/1
minicom.cap:100:[   91.697827] musb-hdrc musb-hdrc.1.auto: qh df62d240 urb dc4ebec0 dev3 ep1in-intr, hw_ep 10, df700680/1
minicom.cap:106:[   91.818066] musb-hdrc musb-hdrc.1.auto: qh dc4eb340 urb df5b7e40 dev4 ep1in-intr, hw_ep 11, df5c3400/1
minicom.cap:149:[   92.475792] musb-hdrc musb-hdrc.1.auto: qh df62d240 urb dc4ebec0 dev3 ep1in-intr, hw_ep 10, df700680/1
minicom.cap:162:[   92.736808] musb-hdrc musb-hdrc.1.auto: qh dc07d5c0 urb dc4ebec0 dev3 ep1in-intr, hw_ep 10, df700680/1
minicom.cap:207:[   93.703046] musb-hdrc musb-hdrc.1.auto: qh df551cc0 urb df65ee40 dev7 ep1in-intr, hw_ep 12, df6a2bc0/1
minicom.cap:215:[   93.977574] musb-hdrc musb-hdrc.1.auto: qh df551cc0 urb df65ee40 dev7 ep1in-intr, hw_ep 12, df6a2bc0/1
minicom.cap:240:[   94.388472] musb-hdrc musb-hdrc.1.auto: qh dc4eb340 urb df5b7e40 dev4 ep1in-intr, hw_ep 11, df5c3400/1
minicom.cap:289:[   95.422325] musb-hdrc musb-hdrc.1.auto: qh dc4eb340 urb df5b7e40 dev4 ep1in-intr, hw_ep 11, df5c3400/1
minicom.cap:305:[   95.688207] musb-hdrc musb-hdrc.1.auto: qh dc4eb340 urb df5b7e40 dev4 ep1in-intr, hw_ep 11, df5c3400/1
minicom.cap:335:[   96.291453] musb-hdrc musb-hdrc.1.auto: qh df551cc0 urb df65ee40 dev7 ep1in-intr, hw_ep 12, df6a2bc0/1
minicom.cap:410:[   97.696976] musb-hdrc musb-hdrc.1.auto: qh df6b70c0 urb dc011f40 dev11 ep1in-intr, hw_ep 2, dd842080/8

Note how the same ep1in-intr was used with different devices and
different hw_eps. OTOH, within the same device, hw_ep was
constant. Hmmm...


-- 
balbi

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