Hi Stefan,

On 08/04/2017 04:38 PM, Stefan Agner wrote:
From: Stefan Agner <stefan.ag...@toradex.com>

This series adds NXP's Serial Download Protocol (SDP) support via
USB for SPL/U-Boot. It allows to download U-Boot via USB from a
(recovered) SPL using the same tools used to download SPL itself
(specifically imx_usb, but also sb_loader seems to work).


The idea has been brought up when the first targets started to make
use of SPL for DDR initialization, see:

There have been lots of discussions surrounding the use of SDP,
and this seems to be a nice alternative to using the i.MX "plugin"
mode that I explored a while back:


The initial SDP implementation (patch 2) requires the payload to
have the imx specific headers (hence the move of the imx header
file in patch 1).

Patch 3 extends image header support beyond the SDP specification,
specifically implements also support for U-Boot headers. This
allows to use the same SPL/U-Boot binaries for recovery as used on
the regular boot device (SD/eMMC). For that to work also the host
side imx_usb tools needed an extension, currently available here:


The full patchset allows to download SPL and U-Boot over USB to a
target in recovery mode using the same usb_imx utility:


The usb_imx utility also has a batch mode which allows to download
multiple artifacts with a single invocation. The details are
outlined in the imx_usb commit message:

In case this patchset gets accepted in U-Boot, I plan to push the
imx_usb changes upstream as well.

Do you have numbers for how much code/data size this adds to SPL?

I believe some i.MX users have struggled to stay within the
size of internal RAM.


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