[PATCH v2] USB: gadget: fastboot: introduce optional flag for fastboot partitions

[Sascha Hauer]

On Thu, Sep 22, 2022 at 03:24:10PM +0200, Johannes Zink wrote:
> On some boards, some partitions exposed to fastboot may become
> unavailable under certain circumstances, e.g. if an SD-Card exposed to
> fastboot is removed.
> 
> Previously, this lead to an error and the fastboot gadget did not
> initialize the remaining partitions exposed via fastboot, e.g. an
> eMMC which usually is permanently soldered on the board.
> 
> This patch allows to append an optional flag 'o' to the description of a
> fastboot partition. If this partition is unavailable at the
> initialization of the fastboot gadget, said partition is skipped, while
> the remaining available partitions are still exposed.
> 
> Signed-off-by: Johannes Zink <j.zink at pengutronix.de>
> ---
> Changes since v1:
>  - moved check for FILE_LIST_OPTIONAL flag to fastboot_add_partition_variables().
>    This allows for cleaner error checking on error conditions (Thanks Sascha)
>  - reworded info message to indicate intended condition on skipping optional
>    partitions rather than indicating an error condition (Thanks Ahmad)
>  - added FILE_LIST_OPTIONAL flag to flags_to_str() (Thanks Ahmad

Applied, thanks

Sascha

> 
>  Documentation/user/usb.rst | 1 +
>  common/fastboot.c          | 8 ++++++++
>  common/file-list.c         | 7 ++++++-
>  include/file-list.h        | 1 +
>  4 files changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/user/usb.rst b/Documentation/user/usb.rst
> index 2479efe9d6..f2f57ead98 100644
> --- a/Documentation/user/usb.rst
> +++ b/Documentation/user/usb.rst
> @@ -65,6 +65,7 @@ Several **flags** are supported, each denoted by a single character:
>  * ``r`` Readback. The partition is allowed to be read back (DFU specific)
>  * ``c`` The file shall be created if it doesn't exist. Needed when a regular file is exported.
>  * ``u`` The partition is a MTD device and shall be flashed with a UBI image.
> +* ``o`` The partition is optional, i.e. if it is not available at initialization time, it is skipped instead of aborting the initialization
>  
>  Example:
>  
> diff --git a/common/fastboot.c b/common/fastboot.c
> index 330a06f5a3..249e953ad6 100644
> --- a/common/fastboot.c
> +++ b/common/fastboot.c
> @@ -95,6 +95,14 @@ static int fastboot_add_partition_variables(struct fastboot *fb,
>  	}
>  
>  	if (ret) {
> +		if (fentry->flags & FILE_LIST_FLAG_OPTIONAL) {
> +			pr_info("skipping unavailable optional partition %s for fastboot gadget\n",
> +				fentry->filename);
> +			ret = 0;
> +			type = "unavailable";
> +			goto out;
> +		}
> +
>  		if (fentry->flags & FILE_LIST_FLAG_CREATE) {
>  			ret = 0;
>  			type = "file";
> diff --git a/common/file-list.c b/common/file-list.c
> index 407b312833..3bb3b39d05 100644
> --- a/common/file-list.c
> +++ b/common/file-list.c
> @@ -88,6 +88,9 @@ static int file_list_parse_one(struct file_list *files, const char *partstr, con
>  			case 'u':
>  				flags |= FILE_LIST_FLAG_UBI;
>  				break;
> +			case 'o':
> +				flags |= FILE_LIST_FLAG_OPTIONAL;
> +				break;
>  			default:
>  				pr_err("Unknown flag '%c'\n", *partstr);
>  				return -EINVAL;
> @@ -113,7 +116,7 @@ static int file_list_parse_one(struct file_list *files, const char *partstr, con
>  
>  static const char *flags_to_str(int flags)
>  {
> -	static char str[sizeof "srcu"];
> +	static char str[sizeof "srcuo"];
>  	char *s = str;;
>  
>  	if (flags & FILE_LIST_FLAG_SAFE)
> @@ -124,6 +127,8 @@ static const char *flags_to_str(int flags)
>  		*s++ = 'c';
>  	if (flags & FILE_LIST_FLAG_UBI)
>  		*s++ = 'u';
> +	if (flags & FILE_LIST_FLAG_OPTIONAL)
> +		*s++ = 'o';
>  
>  	*s = '\0';
>  
> diff --git a/include/file-list.h b/include/file-list.h
> index 5090313739..bcb06979c8 100644
> --- a/include/file-list.h
> +++ b/include/file-list.h
> @@ -8,6 +8,7 @@
>  #define FILE_LIST_FLAG_READBACK	(1 << 1)
>  #define FILE_LIST_FLAG_CREATE	(1 << 2)
>  #define FILE_LIST_FLAG_UBI	(1 << 3)
> +#define FILE_LIST_FLAG_OPTIONAL (1 << 4)
>  
>  struct file_list_entry {
>  	char *name;
> -- 
> 2.30.2
> 
> 
> 

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