FTDI user space on Windows

[Lubomir I. Ivanov]

On 13 September 2018 at 21:44, Bill Perry <bill at billandterrie.com> wrote:
> Just a reminder that last summer I saw that the code in serial_ftdi_read() doesn't guarantee that a timeout occurs
> in the desired timeout period.
> Due to the way it is written, you can get MUCH longer delays when the bytes don't stream in right away or
> This was an issue I was fighting last year when I was trying to get retries to work on the Pelagic data cable with Android.
> It actually affects any ftdi device.
> This is likely an issue on Windows as well.
>
> ftdi_read_data() took a few milliseconds of time before returning and that time is not accounted for.
> And on android the the LIBUSB_ERROR_INTERRUPTED was also happening.
> This caused the while loop to loop for several minutes before timing out.
> My solution (which I posted a patch for to the list back in Nov 2017) was to get rid of slept and to always sleep for 1ms.
> Then rather than comparing slept >= timeout - which doesn't work, was to use gettimofday()
> to check for the elapsed time to check for the desired timeout period.
>

sleeping for small chunks of time can end up being better.
would you like to submit a github PR to address this improvement as
per your experiments?

lubomir
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