[PATCH] doc: usage: man-page for ums command

[Heinrich Schuchardt]

On 6/2/21 3:52 PM, Patrick Delaunay wrote:
> Provide a man-page for the ums command for USB Mass Storage.
>
> Signed-off-by: Patrick Delaunay <patrick.delaunay at foss.st.com>
> ---
>
>   doc/usage/index.rst |  1 +
>   doc/usage/ums.rst   | 54 +++++++++++++++++++++++++++++++++++++++++++++
>   2 files changed, 55 insertions(+)
>   create mode 100644 doc/usage/ums.rst
>
> diff --git a/doc/usage/index.rst b/doc/usage/index.rst
> index 41b247bc62..1bab6ae3e9 100644
> --- a/doc/usage/index.rst
> +++ b/doc/usage/index.rst
> @@ -43,3 +43,4 @@ Shell commands
>      scp03
>      size
>      true
> +   ums
> diff --git a/doc/usage/ums.rst b/doc/usage/ums.rst
> new file mode 100644
> index 0000000000..cf0e3a9479
> --- /dev/null
> +++ b/doc/usage/ums.rst
> @@ -0,0 +1,54 @@
> +.. SPDX-License-Identifier: GPL-2.0+
> +
> +ums command
> +===========
> +
> +Synopsis
> +--------
> +
> +::
> +
> +    <USB_controller> [<devtype>] <dev[:part]>
> +
> +Description
> +-----------
> +
> +Use the USB Mass Storage class (also known as USB MSC or UMS) to make
> +accessible a block device (based on UCLASS_BLK) to a host computing device and
> +to enable file transfers between the host and the U-Boot device.

Thank you for writing this man-page.

Unfortunately it is still unclear to me how to use it. Is this related
to USB OTG? What requirements have to be met to use the command?

> +
> +This command "ums" stays in the USB's treatment loop until user enters Ctrl-C.
> +
> +USB_controller
> +    USB device number
> +
> +devtype
> +    block device interface, defaults to "mmc"
> +
> +dev
> +    device number for devtype
> +
> +part
> +    partition number, defaults to 0 (first partition)
> +
> +Example
> +-------
> +
> +::
> +
> +    => ums 0 mmc 0
> +    => ums 0 usb 1:2
> +
> +Configuration
> +-------------
> +
> +The ums command is only available if CONFIG_CMD_USB_MASS_STORAGE=y.

The symbol does not even depend on USB and mass storage being enabled. I
would have expected CONFIG_USB_GADGET and CONFIG_BLK as requirements.
Either this description or cmd/Kconfig is wrong. I suggest both to be
updated.

Best regards

Heinrich

> +
> +Return value
> +------------
> +
> +The return value $? is set to 0 (true) when the USB stack was successfully
> +started and interrupted Ctrl-C or after USB cable detection issue
> +(timeout or cable removal).
> +
> +If an error occurs, the return value $? is set to 1 (false).
>