Jie Zhang wrote:
> We can't set readbuffer_chunksize larger than MAX_BULK_BUFFER_LENGTH,
> which is defined in libusb-1.0, on Linux. Otherwise, each USB read
> request will be divided into multiple (to be exactly, 4) URBs. The
> last 3 URBs of these 4 URBs will usually result in abnormal reaps
> because we usually request small number of data. The abnormal reaps
> will concatenate empty ftdi packets to other packet on Linux kernel
> older than 2.6.32. libftdi cannot parse such combined packet. This
> will cause issue for UrJTAG when using libftdi-1.0 with libusb-1.0. I
> have committed this patch on the libftdi-1.0 git tree.
>
>
> Jie
>
>
> --
> libftdi - see http://www.intra2net.com/en/developer/libftdi for details.
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> Index: src/ftdi.c
> ===================================================================
> --- src/ftdi.c (revision 3932)
> +++ src/ftdi.c (working copy)
> @@ -1621,6 +1621,14 @@ int ftdi_read_data_set_chunksize(struct
> // Invalidate all remaining data
> ftdi->readbuffer_offset = 0;
> ftdi->readbuffer_remaining = 0;
> +#ifdef __linux__
> + /* We can't set readbuffer_chunksize larger than MAX_BULK_BUFFER_LENGTH,
> + which is defined in libusb-1.0. Otherwise, each USB read request will
> + be divided into multiple URBs. This will cause issues on Linux kernel
> + older than 2.6.32. */
> + if (chunksize > 16384)
> + chunksize = 16384;
Shouldn't this be
> + if (chunksize > MAX_BULK_BUFFER_LENGTH)
> + chunksize = MAX_BULK_BUFFER_LENGTH;
-jim
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