Hi Everyone,
Our Xilinx FPGA driver (zynq-fpga.c) is no longer compatible with
fpga-mgr.c and barfs with:
"Invalid bitstream, could not find a sync word. Bitstream must
be a byte swapped .bin file"
It seems to come from here (inside fpga_mgr_write_init_buf()):
size_t header_size = info->header_size;
It uses header_size to decide whether or not to call
fpga_mgr_write_init() with a NULL buffer and a 0 size, or use a real
buffer and real size, like this:
if (header_size > count)
ret = -EINVAL;
else if (!header_size)
ret = fpga_mgr_write_init(mgr, info, NULL, 0);
else
ret = fpga_mgr_write_init(mgr, info, buf, count);
The trouble is, that if I follow my code path, info->header_size isn't
set by anyone. So it's **ALWAYS** zero. But the value **should** be
128:
static const struct fpga_manager_ops zynq_fpga_ops = {
.initial_header_size = 128,
...
};
The issue seems to have been introduced as part of commit 3cc624beba
which I have linked to here:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/fpga/fpga-mgr.c?id=3cc624beba6310a8a534fb00841f22445a200d54
What I find really interesting is that the original mailing list patch
submission didn't have this bug, and would have worked for us:
+ if (info->header_size)
+ header_size = info->header_size;
+ else
+ header_size = mgr->mops->initial_header_size;
Could this be a viable way to ensure that the FPGA manager driver is
compatible with the zynq-fpga.c driver again?
- DG
