[PATCH v2 0/4] Better smartphone support (Qualcomm)

[Caleb Connolly]

Hi Peter,

On 3/13/25 19:07, Peter Robinson wrote:
> Hey Caleb,
> 
>     Improve support for running U-Boot on [Qualcomm] smartphones, with:
> 
> 
> Is there anything in this that is QCom specific? Like should this also 
> work on the Pinephone phones which have either a Allwinner or Rockchip SoC?

The ideas here could be adapted to other platforms, but unfortunately 
the implementation itself (e.g. the environment file) is Qualcomm 
specific. Every device will be slightly different here and - at least 
with the current approach - it can't be made very generic.

> 
>     * A boot menu which can be entered by holding power during boot
>     * Hang on panic (so errors can be read on the display)
>     * Serial gadget which can be enabled by holding volume down or via
>        boot menu
> 
>     In its current form, U-Boot's boot menu is perfectly adequate, however
>     once an option is picked U-Boot will never return to the menu, always to
>     the CLI.
> 
> 
> I wonder if it makes sense to make this a generic option selectable by 
> Kconfig.

I couldn't really see a nice way to do this. The commands get run 
through the shell interpreter anyways.
> 
>     On a phone (with no keyboard), dropping to the CLI effectively makes the
>     device unusable until manually rebooted, since there is no way to run
>     any commands...
> 
>     To rectify this, let's revive CONFIG_BOOT_RETRY for the hush parser and
>     add an option CONFIG_RETRY_BOOTCMD to run the contents of "bootcmd".
> 
> 
> Is there a way to do this without hush, a bit of thinking out loud by 
> with this hush makes less sense, and compiling it out has the plus of it 
> not being available from a security PoV.

I don't think so, since we rely on the shell to run the commands in the 
menu.
> 
>     This provides for a flexible menu system which we can enter and exit.
>     See qcom-phone.env in patch 1 for more details.
> 
> 
> This over all sounds like a good way forward.
> 
>     Finally, provide some rough-ish documentation to describe how Qualcomm
>     phone support works and outline some debugging steps for when UART and
>     the framebuffer are unavailable.
> 
> 
> Can we make that generic phone?

The techniques described in the doc may apply to non-Qualcomm hardware, 
but I have no experience with it, and I know that a lot of the things I 
describe are Qualcomm specific. For example under what situations a 
Qualcomm device is likely to hang and/or reset itself, as well the 
framebuffer.

> 
> I have both of the pinephones, I can likely try this id there's no 
> specific qcom-isms, or if there's specific features I need to be aware 
> of I can see what they're missing at least.

You could surely write a similar env file for the pinephone with a boot 
menu based on the same logic, I don't think that would be a lot of effort.
> 
>     ---
>     Changes in v3:
>     - Minor wording/clarification improvements in docs
>     - Introduce CONFIG_RETRY_BOOTCMD rather than changing the default
>        behaviour.
>     - Enable some more gadgets in the phone config fragment.
>     - Link to v2: https://lore.kernel.org/u-boot/20241004-qcom-phones-
>     v2-0-c7ab67ac3043 at linaro.org <https://lore.kernel.org/u-
>     boot/20241004-qcom-phones-v2-0-c7ab67ac3043 at linaro.org>
> 
>     Changes in v2:
>     - Fix CONFIG_BUTTON_REMAP_PHONE_KEYS name in qcom-phone.config
>     - Add Tom and Simon to CC
>     - Link to v1: https://lore.kernel.org/r/20240831-qcom-phones-
>     v1-0-08614edd8e35 at linaro.org <https://lore.kernel.org/r/20240831-
>     qcom-phones-v1-0-08614edd8e35 at linaro.org>
> 
>     ---
>     Caleb Connolly (4):
>            board/qualcomm: introduce phone config
>            cli_hush: support running bootcmd on boot retry
>            bootretry: check for bootretry variable changes
>            doc: board/qualcomm: describe phone support and bringup
> 
>       board/qualcomm/qcom-phone.config |  17 ++++++
>       board/qualcomm/qcom-phone.env    |  49 ++++++++++++++++
>       boot/Kconfig                     |   7 +++
>       boot/bootretry.c                 |   2 +
>       common/cli_hush.c                |   6 +-
>       common/cli_hush_upstream.c       |   6 +-
>       doc/board/qualcomm/board.rst     |   5 ++
>       doc/board/qualcomm/index.rst     |   1 +
>       doc/board/qualcomm/phones.rst    | 122 +++++++++++++++++++++++++++
>     ++++++++++++
>       9 files changed, 211 insertions(+), 4 deletions(-)
>     ---
>     base-commit: 78f8c8c58f7d3f7c3a26af4afbd08aba21c14c90
> 
>     Caleb Connolly <caleb.connolly at linaro.org
>     <mailto:caleb.connolly at linaro.org>>
> 

-- 
Caleb (they/them)