[U-Boot] SPL Dfu update

[Michael Trimarchi]

Hi Tom

On Thu, Oct 31, 2013 at 2:20 PM, Tom Rini <trini at ti.com> wrote:
> On Wed, Oct 30, 2013 at 09:11:43PM +0100, Wolfgang Denk wrote:
>> Dear Michael Trimarchi,
>>
>> In message <CAOf5uw=hCkwPaqogCO3KvM1erhS-dvC5BRT4USU3uqKETtTQ7A at mail.gmail.com> you wrote:
>> >
>> > > This does not answer Stefano's question: why do it in SPL, what's
>> > > wrong with loading the real U-Boot for this purpose?
>> >
>> > Because it's not possible, internal memory size of some cpus. You need
>> > to have a way to load the second stage and I'm discussing a general
>> > way to do.
>>
>> I'm not sure that there are many use cases where you have sufficient
>> room for all that is needed for DFU (including I/O buffers); and if
>> you move to RAM early, you have other options as well.
>
> No, it's true.  We have some "small" amount of image download area in
> some sort of on-chip RAM (OMAP3 is between 54 and 62KiB, depending on
> how we think about stack, AM335x is ~110KiB) which is where our first
> stage _has_to_ fit.  We can still do a two-step process here of loading
> a regular SPL and then a full U-Boot, but this requires more complicated
> host side tooling.
>
> But this is what I was trying to highlight, about how Scott's comment is
> right.  What's desired here, rightly is a U-Boot build with limited IO
> and a main loop that drops right into DFU.  You can do this today with
> SPL+U-Boot and a CONFIG_BOOTCOMMAND that just kicks off DFU.  But that
> means transferring more data, which is taking more time and yes,
> programming time is a concern.
>
>> > What is your alternative way?
>>
>> Depending on your hardware there is a zillion ways to do this.  For
>> low to medium volumes good old JTAG is still a very powerful tool; for
>> high volumes you will probably just fit pre-programmed NAND on your
>> board.  And of course there is the growing number of systems that can
>> just boot and install from a SDCard or USB MSD.
>
> Exactly.  But you're leaving out "system boots via USB gadget", which is
> what Michael is trying to solve.
>

This should make more sense. Try to have all the dfu support
in the first stage is complicated for the writing routine but having
just ram loading can be more simple considering the image size

#define STR_HELPER(x) #x
#define STR(x) STR_HELPER(x)
#define DFU_BOARD_FLASHINFO "RAM" STR(DFU_RAM_DEVICE_ADDRESS) ";"

void spl_dfu_load_image()
{
        int ret;
        struct image_header *header;

        printf("SPL load image\n");

        ret = dfu_config_entities(DFU_BOARD_FLASHINFO, "ram", 0);
        g_dnl_register("dfu");
        while(1) {
                if (ctrlc())
                        goto exit;
                ret = usb_gadget_handle_interrupts();
                if (ret)
                        goto exit;
        }

        g_dnl_unregister();
        dfu_free_entities();

        header = (struct image_header *)DFU_RAM_DEVICE_ADDRESS;
        spl_parse_image_header(header);
        memcpy((void *)DFU_RAM_DEVICE_ADDRESS, (void *)spl_image.load_addr,
                spl_image.size);
        return;
exit:
        g_dnl_unregister();
        dfu_free_entities();
}
> --
> Tom


Michael