Date: Thu, 14 Oct 2021 20:23:00 +0000 From: Brian McGovern (bmcgover) via freebsd-questions <freebsd-questions@freebsd.org> To: "freebsd-questions@freebsd.org" <freebsd-questions@freebsd.org> Subject: QQ on maxcount of ftdi interfaces on USB Bus Message-ID: <BL1PR11MB550964F8D69731BF98D7F325C5B89@BL1PR11MB5509.namprd11.prod.outlook.com>
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I'm running a software terminal server on Raspberry Pi 3s using FTDI->RJ45 =
serial cables. Presently running FreeBSD 12.1, but honestly, version doesn'=
t matter as I can move to anything, including 13.
It appears there is some upper limit that is keeping the number of devices =
I can connect to 20. When I add another device, I get the message "usbus0: =
No free USB device index for new device". This lets me track it bak to usb_=
device.c.
>From there, however, it seems to spread out to a number of possible values =
- EHCI_MAX_DEVICES, XHCI_MAX_DEVICES, OHCI_MAX_DEVICES, etc, based on the =
controller and instance. It eventually seems to reconverge on USB_MAX_DEVIC=
ES, which appears to be 128 in most cases.
Before I go and blow an overnight building an updated kernel on a Pi, I'm c=
urious if anyone can tell me if just bumping up USB_MAX_DEVICES will get me=
a handful more ports - say, setting it to 160 or 192 - or if I'm just goin=
g to start breaking things, and the "right answer" (tm) is to start breakin=
g up the hardware at, say, 16 ports each to stay under the limits?
-Brian
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