[PATCH v4 7/7] doc: board: Add document for DFU boot on am62x SoCs

[Sjoerd Simons]

On Fri, 2024-01-12 at 06:36 -0600, Nishanth Menon wrote:
> On 09:52-20240112, Sjoerd Simons wrote:
> > 
> > +DFU based boot
> > +--------------
> > +
> > +To boot the board over DFU, ensure there is no SD card inserted
> > with a
> > +bootloader. Hold the USR switch while plugging into the Type C to
> > boot into DFU
> > +mode. After power-on the build artifacts needs to be uploaded one
> > by one with a
> > +tool like dfu-util.
> 
> Don't we also need a wiped out emmc unfortunately?

Nope just not having an SD card without boot artifacts is enough (or to
keep things simple no SD card). the USR switch changes the bootmode to
have SD as primary, DFU as fallback, so what's on the eMMC is luckily
not relevant.

So i've been happily testing with the factory eMMC image untouched to
allow me to compare against the factory u-boot behaviour 

> 
> > +
> > +.. include::  ../ti/am62x_sk.rst
> > +    :start-after: .. am62x_evm_rst_include_start_dfu_boot
> > +    :end-before: .. am62x_evm_rst_include_end_dfu_boot
> > +
> >  Debugging U-Boot
> >  ----------------
> >  
> > diff --git a/doc/board/ti/am62x_sk.rst b/doc/board/ti/am62x_sk.rst
> > index b12dc85f06b..904a54cd5ff 100644
> > --- a/doc/board/ti/am62x_sk.rst
> > +++ b/doc/board/ti/am62x_sk.rst
> > @@ -105,6 +105,20 @@ Set the variables corresponding to this
> > platform:
> >  
> >  * 3.1 R5:
> >  
> > +.. include::  ../ti/k3.rst
> > +    :start-after: .. k3_rst_include_start_build_steps_spl_r5
> > +    :end-before: .. k3_rst_include_end_build_steps_spl_r5
> > +
> > +* 3.1.1 Alternatively build R5 for DFU boot:
> > +
> > +As the SPL size can get to big when building with support for
> > booting both from
> > +local storage *and* DFU an extra config fragment should be used to
> > enable DFU
> > +support (and disable storage support)
> > +
> > +.. prompt:: bash $
> > +
> > +  export UBOOT_CFG_CORTEXR=${UBOOT_CFG_CORTEXR}
> > am62x_r5_usbdfu.config
> > +
> >  .. include::  ../ti/k3.rst
> >      :start-after: .. k3_rst_include_start_build_steps_spl_r5
> >      :end-before: .. k3_rst_include_end_build_steps_spl_r5
> > @@ -251,6 +265,29 @@ https://www.ti.com/lit/pdf/spruiv7 under the
> > `Boot Mode Pins` section.
> >  
> >  For SW2 and SW1, the switch state in the "ON" position = 1.
> >  
> > +DFU based boot
> > +--------------
> > +
> > +To boot the board over DFU, set the switches to DFU mode and
> > connect to the
> > +USB Type C DRD Port on the board. After power-on the build
> > artifacts needs to be
> > +uploaded one by one with a tool like dfu-util.
> > +
> > +.. am62x_evm_rst_include_start_dfu_boot
> > +
> > +The initial ROM will have a DFU alt named `bootloader` for the
> > initial R5 spl
> > +upload. The next stages as exposed by u-boot have target alts
> > matching the name
> > +of the artifacts, for these a USB reset has to be done after each
> > upload.
> > +
> > +When using dfu-util the following commands can be used to boot to
> > a u-boot shell:
> > +
> > +.. prompt:: bash $
> > +
> > +  dfu-util -a bootloader -D tiboot3.bin
> > +  dfu-util -R -a tispl -D tispl.bin
> > +  dfu-util -R -a u-boot.img -D u-boot.img
> > +
> > +.. am62x_evm_rst_include_end_dfu_boot
> > +
> >  Debugging U-Boot
> >  ----------------
> >  
> > -- 
> > 2.43.0
> > 
> 

-- 
Sjoerd Simons
Collabora Ltd.