[PATCH] dfu: define a callback function for the dfu_alt_info environment variable

[Rasmus Villemoes]

I'm trying to use dfu-util for bootstrapping an stm32mp board. It
mostly works fine, but something goes horribly wrong as soon as I make
use of the ability to run arbitrary u-boot shell commands. The shell
commands themselves work fine, but the heuristic "dfu_alt_info may
have changed, we have to reinit" seems to cause the board and/or my
host machine to go into some bad state, and further dfu-util commands
fail.

U-Boot already has a mechanism whereby C code can be told about
changes to specific environment variables. So instead of always doing
re-init, add a hook to the dfu_alt_info variable so that we only do
set dfu_reinit_needed if the commands actually did modify that
variable.

Signed-off-by: Rasmus Villemoes <rasmus.villem...@prevas.dk>
---
 drivers/dfu/dfu.c      | 16 ++++++++++++++++
 drivers/dfu/dfu_mmc.c  |  3 ++-
 include/dfu.h          |  1 +
 include/env_callback.h |  7 +++++++
 4 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/drivers/dfu/dfu.c b/drivers/dfu/dfu.c
index 540d48fab77..7a4d7ba2a7f 100644
--- a/drivers/dfu/dfu.c
+++ b/drivers/dfu/dfu.c
@@ -27,6 +27,21 @@ static unsigned long dfu_timeout = 0;
 #endif
 
 bool dfu_reinit_needed = false;
+bool dfu_alt_info_changed = false;
+
+static int on_dfu_alt_info(const char *name, const char *value, enum env_op op,
+                          int flags)
+{
+       switch (op) {
+       case env_op_create:
+       case env_op_overwrite:
+       case env_op_delete:
+               dfu_alt_info_changed = true;
+               break;
+       }
+       return 0;
+}
+U_BOOT_ENV_CALLBACK(dfu_alt_info, on_dfu_alt_info);
 
 /*
  * The purpose of the dfu_flush_callback() function is to
@@ -152,6 +167,7 @@ int dfu_init_env_entities(char *interface, char *devstr)
        int ret = 0;
 
        dfu_reinit_needed = false;
+       dfu_alt_info_changed = false;
 
 #ifdef CONFIG_SET_DFU_ALT_INFO
        set_dfu_alt_info(interface, devstr);
diff --git a/drivers/dfu/dfu_mmc.c b/drivers/dfu/dfu_mmc.c
index 8f7ecfa8fc7..c19eb919388 100644
--- a/drivers/dfu/dfu_mmc.c
+++ b/drivers/dfu/dfu_mmc.c
@@ -232,7 +232,8 @@ int dfu_flush_medium_mmc(struct dfu_entity *dfu)
                break;
        case DFU_SCRIPT:
                /* script may have changed the dfu_alt_info */
-               dfu_reinit_needed = true;
+               if (dfu_alt_info_changed)
+                       dfu_reinit_needed = true;
                break;
        case DFU_RAW_ADDR:
        case DFU_SKIP:
diff --git a/include/dfu.h b/include/dfu.h
index 6c5431b3948..e25588c33cb 100644
--- a/include/dfu.h
+++ b/include/dfu.h
@@ -517,6 +517,7 @@ static inline int dfu_fill_entity_virt(struct dfu_entity 
*dfu, char *devstr,
 #endif
 
 extern bool dfu_reinit_needed;
+extern bool dfu_alt_info_changed;
 
 #if CONFIG_IS_ENABLED(DFU_WRITE_ALT)
 /**
diff --git a/include/env_callback.h b/include/env_callback.h
index 8e500aaaf80..66cc8309e71 100644
--- a/include/env_callback.h
+++ b/include/env_callback.h
@@ -69,6 +69,12 @@
 #define BOOTSTD_CALLBACK
 #endif
 
+#ifdef CONFIG_DFU
+#define DFU_CALLBACK "dfu_alt_info:dfu_alt_info,"
+#else
+#define DFU_CALLBACK
+#endif
+
 /*
  * This list of callback bindings is static, but may be overridden by defining
  * a new association in the ".callbacks" environment variable.
@@ -79,6 +85,7 @@
        NET_CALLBACKS \
        NET6_CALLBACKS \
        BOOTSTD_CALLBACK \
+       DFU_CALLBACK \
        "loadaddr:loadaddr," \
        SILENT_CALLBACK \
        "stdin:console,stdout:console,stderr:console," \
-- 
2.46.0