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 When using 12 ports and performing serial test (a pair of ports is connected via null-modem cable and a rather short string ca. 90 characters will be sent alternating at 1200 and 115200b/s, testing scripts are written in Python and running as own processes per a pair of ports) there are no timeouts, i.e. all sent characters will be received. As soon as I open ports 13 and 14 I start to get arbitrary timeouts (from test software point of view) on all ports. In order to check, if ftdi_sio has primary to do with this issue, I've performed the same test on a PC and PandaBoard Rev. A2 (EHCI port) and there were no issues with 16 ports. So it seems to have something to do with am335x + musb + number of end points. Any idea? Let me know, if you need our test script. Yegor -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html