On Mon, Apr 25, 2011 at 5:53 PM, Carl-Daniel Hailfinger < [email protected]> wrote:
> Hi, > > Am 26.04.2011 00:43 schrieb David Hendricks: > > I'm using Flashrom with an FTDI FT4232H to read a 1MB SPI ROM (w25q80), >> but >> am encountering difficulties. I believe we may be missing some steps in >> ft2232_spi_init(), however I don't have much experience with libftdi or >> usb >> debugging so I hope someone on the list does :-) >> >> When the programmer is plugged into a "full-speed" USB port slow, things >> seem to work well. However, when plugged into a "high-speed" port, bytes >> simply disappear. There does not seem to be a pattern with regard to where >> the problems start. Sometimes it will fail very early and Flashrom will >> not >> be able to detect the chip. Sometimes we'll get lucky and we can read the >> full chip. It can fail anywhere in between. >> >> The only pattern I've seen is that usb bulk reads return less than the >> requested number of bytes before it fails entirely. For example, if we >> request 256 bytes, then it might return 256-N data bytes. libftdi will >> request the remaining bytes, and libusb will provide the remaining N data >> bytes. On the next 256-byte request, libusb will not return any data bytes >> (only the 2-byte USB header). >> >> > > This is a known problem which may happen with older (>6 months) libftdi > and/or older kernels (>6 months) and/or older libusb. The libftdi mailing > list probably has more information. If you can reproduce the issue with a > recent kernel (2.6.36 or newer) and recent libusb and libftdi from git, > please tell the libftdi mailing list. > IIRC some flashrom patch (sent in the last 6 months or so) tried to make > sure that such issues are worked around in flashrom by requiring recent > libftdi and by setting a parameter which reduces the likelihood of that > event. Sorry, I don't have more details handy right now. Quick follow up -- I got a chance to try flashrom out with the FT4232H out on machine with a 2.6.38 kernel and it worked great, EHCI high speed and all :-) Thanks for the pointer! -- David Hendricks (dhendrix) Systems Software Engineer, Google Inc.
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