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

[Bin Liu]

On 10/14/2015 12:19 PM, Felipe Balbi wrote:

Hi,

Bin Liu <b-...@ti.com> writes:
On 10/14/2015 12:05 PM, Felipe Balbi wrote:

Hi,

Bin Liu <b-...@ti.com> writes:
Felipe,

On 10/14/2015 11:25 AM, Felipe Balbi wrote:

Hi,

Bin Liu <b-...@ti.com> writes:
On 10/14/2015 10:56 AM, Felipe Balbi wrote:

Hi,

Bin Liu <b-...@ti.com> writes:
Hi,

On 10/13/2015 01:22 PM, Felipe Balbi wrote:
Yegor Yefremov <yegorsli...@googlemail.com> writes:
On Mon, Oct 12, 2015 at 11:34 AM, Yegor Yefremov
<yegorsli...@googlemail.com> 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

Maybe I am wrong, but ep1in-intr is the EP reference to the device EP,
while hw_ep is the reference to MUSB host EP.

We can't really know which EP the device side is using, right ? :-) The

Right, ep1in-intr is the EP# from the descriptor.

device sides gives us an address in the EP descriptor, but that's just a
USB view, we don't know which hw endpoint the device is using; we only

The host does not have to know the hw EP on the device side.

know its USB address.

The host know the device address and each EP reported from the 
descriptors. That is all for communication.


constant. Hmmm...

My understanding here is that a dedicated MUSB EP is allocated
permanently for each device.

Could be, it has been quite a long time since I messed around that part
of MUSB.

Hope you can pick it up, I have a list of issues with MUSB. I did not 
send them out just because I know you have other high priority things to 
do. ;)

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