[U-Boot] [PATCH 2/3] common: dfu: ignore reset for spl-dfu

[Lukasz Majewski <lukma@denx.de>]

On Wed, 26 Apr 2017 12:24:06 -0400
Tom Rini <trini@konsulko.com> wrote:

> On Wed, Apr 26, 2017 at 03:58:27PM +0000, B, Ravi wrote:
> > Hi Tom
> > 
> > >> The SPL-DFU feature enable to load and execute u-boot over usb
> > >> from PC using dfu-util.
> > >> Hence dfu-reset should not be issued
> > >> when dfu-util -R switch is issued.
> > >> 
> > >> Signed-off-by: Ravi Babu <ravibabu@ti.com>
> > >> ---
> > >>  common/dfu.c | 3 +++
> > >>  1 file changed, 3 insertions(+)
> > >> 
> > >> diff --git a/common/dfu.c b/common/dfu.c index 0e9f5f5..fa77526
> > >> 100644 --- a/common/dfu.c
> > >> +++ b/common/dfu.c
> > >> @@ -87,6 +87,9 @@ exit:
> > >>  	g_dnl_unregister();
> > >>  	board_usb_cleanup(usbctrl_index, USB_INIT_DEVICE);
> > >>  
> > >> +#ifdef CONFIG_SPL_BUILD
> > >> +	dfu_reset = 0;
> > >> +#endif
> > >>  	if (dfu_reset)
> > >>  		run_command("reset", 0);
> > 
> > >So we "fix" some of the problems we see by saying that you can't
> > >reset the board in SPL via DFU.  I think maybe we should instead
> > >drop run_command here and make reset-via-DFU call do_reset()
> > >directly like some other small-size-required cases do.  This will
> > >let us drop the command >requirement here but still allow for "use
> > >DFU to flash and reset the board with just SPL" as a use-case.
> > >Thanks!
> > 
> > The SPL-DFU will load and execute u-boot.img from RAM.  If we issue
> > dfu-reset (-R switch), this leads to cpu-reset and we lost the
> > purpose of SPL-DFU itself.  Hence dfu-reset issue shall not be
> > issued for SPL-DFU. 

It seems like a valid use case - maybe it would be beneficial to add
Kconfig option (CONFIG_DFU_SPL_NO_RESET) to give the user possibility
to decide (and in this way document it?).

> > 
> > I agree, the dfu-reset is needed in u-boot, after flashing images to
> > QSPI/eMMC/SD using the DFU to execute newly loaded image.  So,
> > dfu-reset is needed for u-boot, but not required for SPL-DFU.
> > 
> > For u-boot, we can continue to use run_command() for dfu-reset.
> 
> OK.  I guess if someone else wants to try and use SPL for DFU flashing
> that requires more work and they can address the above then, thanks!
> 
> Reviewed-by: Tom Rini <trini@konsulko.com>
> 




Best regards,

Lukasz Majewski

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