Cypress-based USB-serial converters and Linux

Dec 12, 2004 4 Replies
L

(Xposted to c.a.e because we've been talking about these adapters there recently).



I'm trying to use a Cypress-based USB-serial adapter to connect an 8-bit embedded system

formatting link
to a Linux-based computer. Actually, I want to get it working on PPC Linux running on an MPC8241 but as a first step, I'm trying to get it to work on a regular PC.



I upgraded to 2.6.10-rc3 specifically to get the cypress_m8 driver. It loads OK when I insert the cable, but when I power up the external device and it starts sending bytes, I get a kernel message:



usbhid: probe of 1-2.4:1.0 failed with error -5



(which is -EIO)



When I attempt to send any byte to the external device, I get:



cyphidcom ttyUSB0: cypress_write - usb_submit_urb (write interrupt) failed with status -19



(which is -ENODEV)



Has anyone seen this kind of behavior? Any fixes?



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L

The usbhid error -EIO just means that this subsystem should not claim the device, which is the standard when the device is hid based (purposfully blacklisted so usb-serial can take it over). The -ENODEV error however is new to me. Give me a few hours to prepare a patch for rc3 with the latest development build.

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L

Hi Lonnie,

Great :) FWIW, I am running at 115k2 8N1 with no flow control, using minicom (at the moment). I've also experimented with the uisp in-system programming tool for the Atmel STK500 and while it doesn't show the kernel errors,

BTW, I would have expected to get the blacklist error when the driver loads, no? It doesn't seem to work that way. Seems like the driver loads without any messages, then once the first byte arrives and the calling app tries to read it, that's when it reports the -EIO err.

-ENODEV happens when the app tries to write to the port.

I have the system working with other USB-serial adapters, so I know there isn't a systemwide problem (though I gotta say, USB-serial isn't very reliable overall!)

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L

Let me know if that patch works. I'll be submitting the latest development release soon to usb-devel so it might make it into 2.6.10 before it's released over the holidays.

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L

Er... where did you post that patch? Happy to test it tonight as long as I can find it :)

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