On Sat, Apr 09, 2022 at 01:04:23PM +0800, Xu Yilun wrote:
> On Thu, Apr 07, 2022 at 04:36:56PM +0300, Ivan Bornyakov wrote:
> >
> > ... snip ...
> >
> > @@ -148,12 +149,10 @@ static int fpga_mgr_write_init_buf(struct fpga_manager *mgr,
> > int ret;
> >
> > mgr->state = FPGA_MGR_STATE_WRITE_INIT;
> > - if (!mgr->mops->initial_header_size)
> > - ret = fpga_mgr_write_init(mgr, info, NULL, 0);
> > - else
> > - ret = fpga_mgr_write_init(
> > - mgr, info, buf, min(mgr->mops->initial_header_size, count));
> > + if (mgr->mops->initial_header_size)
> > + count = min(mgr->mops->initial_header_size, count);
> >
> > + ret = fpga_mgr_write_init(mgr, info, buf, count);
>
> Here we pass the whole buffer for write_init(). Maybe it works for mapped buf,
> but still doesn't work for sg buf.
>
> It is also inefficient if we change to map and copy all sg buffers just for
> write_init().
>
> We could discuss on the solution.
>
> My quick mind is we introduce an optional fpga_manager_ops.parse_header()
> callback, and a header_size (dynamic header size) field in
> fpga_image_info. FPGA core starts with mapping a buf of initial_header_size
> for parse_header(), let the drivers decide the dynamic header_size.
>
> The parse_header() could be called several times with updated dynamic
> header_size, if drivers doesn't get enough buffer for final decision and
> return -EAGAIN.
>
> Then write_init() be called with the final dynamic header size.
>
> For mapped buffer, just passing the whole buffer for write_init() is
> fine.
>
Ok, that's sounds reasonable. Should we pass PAGE_SIZE of a buffer to
the parse_header() if initial_header_size is not set? The other option
would be to make initial_header_size to be mandatory for usage of
parse_header().
> >
> > ... snip ...
> >
> > @@ -98,6 +101,8 @@ struct fpga_image_info {
> > struct sg_table *sgt;
> > const char *buf;
> > size_t count;
> > + size_t bitstream_start;
>
> How about we name it header_size?
>
> > + size_t bitstream_size;
>
> And how about data_size?
>
Sure, I don't mind.
