libftdi Archives

Subject: _ftdi_determine_max_packet_size reports wrong value in some cases

From: Алексей Косилин <kosilin75@xxxxxxxxx>
To: libftdi@xxxxxxxxxxxxxxxxxxxxxxx
Date: Sun, 26 Jun 2011 15:32:35 +0400
Hi!

As i have discovered, in some cases (at least in my hw config) the function reports zero max packet size. I'm not sure what exactly happens (i'm not a expert in libusb and low-level USB programming), but i definitely see, that field wMaxPacketSize of the first device endpoint is "0" while second endpoint has normal packet size - 64.

So, i suggest to cycle through all endpoints of the given device config / interface / altsetting to find first non-zero max packet size instead of just using wMaxPacketSize of the first endpoint.

Patch file with the changes i've attached to this mail.

lsusb output:
Bus 003 Device 005: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC

Best regards,
Alexey Kosilin


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Attachment: ftdi.c.patch
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