cmd: mtdparts: Probe MTD devices in mtdparts_init()

Calling "mtdparts" currently fails when its called before any other mtd command (or ubi command) has been called. The MTD devices are not probed at this point and therefore it fails e.g. with this message:

=> mtdparts
Device spi-nand0 not found!

This patch adds a call to mtd_probe_devices() to mtdparts_init() to solve this issue. This also fixes a problem when calling "ubi part" as first flash storage related command.

Here also the warning from
above is printed without this patch.

Signed-off-by Stefan Roese <[email protected]>

Cc Miquel Raynal <[email protected]>

Cc Boris Brezillon <[email protected]>

Cc Jagan Teki <[email protected]>

---
 cmd/mtdparts.c | 4 ++++
 1 file changed, 4 insertions(+)

cmd/mtdparts.c +4 -0

index f7ed1a0779..d90e568143 100644
@@ -73,6 +73,7 @@
 #include <common.h>
 #include <command.h>
 #include <malloc.h>
+#include <mtd.h>
 #include <jffs2/load_kernel.h>
 #include <linux/list.h>
 #include <linux/ctype.h>

@@ -1726,6 +1727,9 @@ int mtdparts_init(void)
 	char tmp_ep[PARTITION_MAXLEN + 1];
 	char tmp_parts[MTDPARTS_MAXLEN];
 
+	/* First probe all MTD devices */
+	mtd_probe_devices();
+
 	debug("\n---mtdparts_init---\n");
 	if (!initialized) {
 		INIT_LIST_HEAD(&mtdids);

Quoted 4 lines · On Tue, 30 Oct 2018 10:51:51 +0100 Stefan Roese <[email protected]> wrote:

Calling "mtdparts" currently fails when its called before any other mtd command (or ubi command) has been called. The MTD devices are not probed at this point and therefore it fails e.g. with this message:

Quoted 2 lines

=> mtdparts
Device spi-nand0 not found!

IIRC, we decided that mtdparts should not call mtd_probe_devices() to encourage people to stop using it.

Quoted 4 lines

This patch adds a call to mtd_probe_devices() to mtdparts_init() to solve this issue. This also fixes a problem when calling "ubi part" as first flash storage related command.

Hm, this one is unexpected. Miquel, any idea why this happens. Do we need to enable a specific option if we want mtd_probe_devices() to be called in the ubi part path?

Quoted 27 lines

Here also the warning from
above is printed without this patch.

Signed-off-by Stefan Roese <[email protected]>

Cc Miquel Raynal <[email protected]>

Cc Boris Brezillon <[email protected]>

Cc Jagan Teki <[email protected]>

---
  cmd/mtdparts.c | 4 ++++
  1 file changed, 4 insertions(+)

cmd/mtdparts.c +1 -0

index f7ed1a0779..d90e568143 100644
@@ -73,6 +73,7 @@
  #include <common.h>
  #include <command.h>
  #include <malloc.h>
+#include <mtd.h>
  #include <jffs2/load_kernel.h>
  #include <linux/list.h>
  #include <linux/ctype.h>

@@ -1726,6 +1727,9 @@ int mtdparts_init(void)
  	char tmp_ep[PARTITION_MAXLEN + 1];
  	char tmp_parts[MTDPARTS_MAXLEN];
 

cmd/mtdparts.c int mtdparts_init(void) · line 1735

Quoted 6 lines

cmd/mtdparts.c +3 -0

+	/* First probe all MTD devices */
+	mtd_probe_devices();
+
  	debug("\n---mtdparts_init---\n");
  	if (!initialized) {
  		INIT_LIST_HEAD(&mtdids);

Hi Boris,

Quoted 7 lines · Boris Brezillon

Quoted 4 lines · On Tue, 30 Oct 2018 10:51:51 +0100 Stefan Roese <[email protected]> wrote:

Calling "mtdparts" currently fails when its called before any other mtd command (or ubi command) has been called. The MTD devices are not probed at this point and therefore it fails e.g. with this message:

Quoted 5 lines

Quoted 2 lines

=> mtdparts
Device spi-nand0 not found!

IIRC, we decided that mtdparts should not call mtd_probe_devices() to encourage people to stop using it.

I see. But I don't quite get how this missing call (and reslting error message) would encourage people to stop using it.

Quoted 8 lines

Quoted 4 lines

This patch adds a call to mtd_probe_devices() to mtdparts_init() to solve this issue. This also fixes a problem when calling "ubi part" as first flash storage related command.

Hm, this one is unexpected. Miquel, any idea why this happens. Do we need to enable a specific option if we want mtd_probe_devices() to be called in the ubi part path?

Please note that "ubi part part-foo" does still work. It only prints this error message before attaching the MTD partition. The error is printed because of this call-chain:

ubi_part()
-> ubi_detach()

     -> mtdparts_init()  

So again, mtdparts_init() is called without the MTD devices being probed.

Quoted 16 lines · On Tue, 30 Oct 2018 11:13:37 +0100 Stefan Roese <[email protected]> wrote:

Hi Boris,

Quoted 12 lines · Boris Brezillon

Quoted 6 lines · On Tue, 30 Oct 2018 10:51:51 +0100 Stefan Roese <[email protected]> wrote:

Calling "mtdparts" currently fails when its called before any other mtd command (or ubi command) has been called. The MTD devices are not probed at this point and therefore it fails e.g. with this message:

=> mtdparts
Device spi-nand0 not found!

IIRC, we decided that mtdparts should not call mtd_probe_devices() to encourage people to stop using it.

Quoted 2 lines

I see. But I don't quite get how this missing call (and reslting error message) would encourage people to stop using it.

You're right, this message does not encourage people to stop using mtdparts on existing setups (mtdparts should work just fine on any MTD devices except SPI NANDs) but it does discourage them from using it on spi-nand devices since it returns an error.

Quoted 17 lines

Quoted 8 lines

Quoted 4 lines

This patch adds a call to mtd_probe_devices() to mtdparts_init() to solve this issue. This also fixes a problem when calling "ubi part" as first flash storage related command.

Hm, this one is unexpected. Miquel, any idea why this happens. Do we need to enable a specific option if we want mtd_probe_devices() to be called in the ubi part path?

Please note that "ubi part part-foo" does still work. It only prints this error message before attaching the MTD partition. The error is printed because of this call-chain:

ubi_part()
-> ubi_detach()

      -> mtdparts_init()

Quoted 2 lines

So again, mtdparts_init() is called without the MTD devices being probed.

I guess we forgot to remove this mtdparts_init() call from the detach path. I think it's no longer needed since we now call mtd_probe_devices() in ubi_part(), and mtd_probe_devices() will take care of creating MTD partitions based on the mtdparts= and mtdids= variables.

Quoted 22 lines · Boris Brezillon

Quoted 18 lines · On Tue, 30 Oct 2018 11:13:37 +0100 Stefan Roese <[email protected]> wrote:

Hi Boris,

Quoted 7 lines · Boris Brezillon

Quoted 4 lines · On Tue, 30 Oct 2018 10:51:51 +0100 Stefan Roese <[email protected]> wrote:

Calling "mtdparts" currently fails when its called before any other mtd command (or ubi command) has been called. The MTD devices are not probed at this point and therefore it fails e.g. with this message:

Quoted 5 lines

Quoted 2 lines

=> mtdparts
Device spi-nand0 not found!

IIRC, we decided that mtdparts should not call mtd_probe_devices() to encourage people to stop using it.

I see. But I don't quite get how this missing call (and reslting error message) would encourage people to stop using it.

Quoted 4 lines

You're right, this message does not encourage people to stop using mtdparts on existing setups (mtdparts should work just fine on any MTD devices except SPI NANDs) but it does discourage them from using it on spi-nand devices since it returns an error.

IMHO, that's more confusing than discouraging.

Quoted 18 lines

Quoted 18 lines

Quoted 9 lines

Quoted 5 lines

This patch adds a call to mtd_probe_devices() to mtdparts_init() to solve this issue. This also fixes a problem when calling "ubi part" as first flash storage related command.

Hm, this one is unexpected. Miquel, any idea why this happens. Do we need to enable a specific option if we want mtd_probe_devices() to be called in the ubi part path?

Please note that "ubi part part-foo" does still work. It only prints this error message before attaching the MTD partition. The error is printed because of this call-chain:

ubi_part()
-> ubi_detach()

      -> mtdparts_init()  

Quoted 8 lines

Quoted 2 lines

So again, mtdparts_init() is called without the MTD devices being probed.

I guess we forgot to remove this mtdparts_init() call from the detach path. I think it's no longer needed since we now call mtd_probe_devices() in ubi_part(), and mtd_probe_devices() will take care of creating MTD partitions based on the mtdparts= and mtdids= variables.

A quick test reveals that this removal does not remove the error message. Instead the command does not work anymore at all:

=> ubi part nand
Partition nand not found!

Before (and without my patch) its this:

=> ubi part nand
Device spi-nand0 not found!
Error initializing mtdparts!
ubi0: attaching mtd2
ubi0: scanning is finished
ubi0: attached mtd2 (name "nand", size 128 MiB)
...

Thanks,
Stefan

Quoted 19 lines · Boris Brezillon

Quoted 16 lines · On Tue, 30 Oct 2018 11:13:37 +0100 Stefan Roese <[email protected]> wrote:

Hi Boris,

Quoted 12 lines · Boris Brezillon

Quoted 6 lines · On Tue, 30 Oct 2018 10:51:51 +0100 Stefan Roese <[email protected]> wrote:

Calling "mtdparts" currently fails when its called before any other mtd command (or ubi command) has been called. The MTD devices are not probed at this point and therefore it fails e.g. with this message:

=> mtdparts
Device spi-nand0 not found!

IIRC, we decided that mtdparts should not call mtd_probe_devices() to encourage people to stop using it.

Quoted 7 lines

Quoted 2 lines

I see. But I don't quite get how this missing call (and reslting error message) would encourage people to stop using it.

You're right, this message does not encourage people to stop using mtdparts on existing setups (mtdparts should work just fine on any MTD devices except SPI NANDs) but it does discourage them from using it on spi-nand devices since it returns an error.

IMHO, that's more confusing than discouraging.

Quoted 17 lines

Quoted 17 lines

Quoted 8 lines

Quoted 4 lines

This patch adds a call to mtd_probe_devices() to mtdparts_init() to solve this issue. This also fixes a problem when calling "ubi part" as first flash storage related command.

Hm, this one is unexpected. Miquel, any idea why this happens. Do we need to enable a specific option if we want mtd_probe_devices() to be called in the ubi part path?

Please note that "ubi part part-foo" does still work. It only prints this error message before attaching the MTD partition. The error is printed because of this call-chain:

ubi_part()
-> ubi_detach()

      -> mtdparts_init()  

Quoted 8 lines

Quoted 2 lines

So again, mtdparts_init() is called without the MTD devices being probed.

I guess we forgot to remove this mtdparts_init() call from the detach path. I think it's no longer needed since we now call mtd_probe_devices() in ubi_part(), and mtd_probe_devices() will take care of creating MTD partitions based on the mtdparts= and mtdids= variables.

A quick test reveals that this removal does not remove the error message. Instead the command does not work anymore at all:

=> ubi part nand
Partition nand not found!

Before (and without my patch) its this:

=> ubi part nand
Device spi-nand0 not found!
Error initializing mtdparts!
ubi0: attaching mtd2
ubi0: scanning is finished
ubi0: attached mtd2 (name "nand", size 128 MiB)

Quoted 63 lines · On Tue, 30 Oct 2018 11:59:13 +0100 Stefan Roese <[email protected]> wrote:

Quoted 19 lines · Boris Brezillon

Quoted 16 lines · On Tue, 30 Oct 2018 11:13:37 +0100 Stefan Roese <[email protected]> wrote:

Hi Boris,

Quoted 12 lines · Boris Brezillon

Quoted 6 lines · On Tue, 30 Oct 2018 10:51:51 +0100 Stefan Roese <[email protected]> wrote:

Calling "mtdparts" currently fails when its called before any other mtd command (or ubi command) has been called. The MTD devices are not probed at this point and therefore it fails e.g. with this message:

=> mtdparts
Device spi-nand0 not found!

IIRC, we decided that mtdparts should not call mtd_probe_devices() to encourage people to stop using it.

Quoted 7 lines

Quoted 2 lines

I see. But I don't quite get how this missing call (and reslting error message) would encourage people to stop using it.

You're right, this message does not encourage people to stop using mtdparts on existing setups (mtdparts should work just fine on any MTD devices except SPI NANDs) but it does discourage them from using it on spi-nand devices since it returns an error.

IMHO, that's more confusing than discouraging.

Quoted 17 lines

Quoted 17 lines

Quoted 8 lines

Quoted 4 lines

This patch adds a call to mtd_probe_devices() to mtdparts_init() to solve this issue. This also fixes a problem when calling "ubi part" as first flash storage related command.

Hm, this one is unexpected. Miquel, any idea why this happens. Do we need to enable a specific option if we want mtd_probe_devices() to be called in the ubi part path?

Please note that "ubi part part-foo" does still work. It only prints this error message before attaching the MTD partition. The error is printed because of this call-chain:

ubi_part()
-> ubi_detach()

      -> mtdparts_init()    

Quoted 8 lines

Quoted 2 lines

So again, mtdparts_init() is called without the MTD devices being probed.

I guess we forgot to remove this mtdparts_init() call from the detach path. I think it's no longer needed since we now call mtd_probe_devices() in ubi_part(), and mtd_probe_devices() will take care of creating MTD partitions based on the mtdparts= and mtdids= variables.

A quick test reveals that this removal does not remove the error message. Instead the command does not work anymore at all:

=> ubi part nand
Partition nand not found!

Quoted 8 lines

Before (and without my patch) its this:

=> ubi part nand
Device spi-nand0 not found!
Error initializing mtdparts!
ubi0: attaching mtd2
ubi0: scanning is finished
ubi0: attached mtd2 (name "nand", size 128 MiB)

I think I found what's missing in mtd_probe_devices(): we don't use the default mtdparts and mtdids when those env vars are NULL (see what's done in mtdparts_init() to handle this case [1]).

Quoted 75 lines · On Tue, 30 Oct 2018 23:02:50 +0100 Boris Brezillon…

Quoted 63 lines · On Tue, 30 Oct 2018 11:59:13 +0100 Stefan Roese <[email protected]> wrote:

Quoted 19 lines · Boris Brezillon

Quoted 16 lines · On Tue, 30 Oct 2018 11:13:37 +0100 Stefan Roese <[email protected]> wrote:

Hi Boris,

Quoted 12 lines · Boris Brezillon

Quoted 6 lines · On Tue, 30 Oct 2018 10:51:51 +0100 Stefan Roese <[email protected]> wrote:

Calling "mtdparts" currently fails when its called before any other mtd command (or ubi command) has been called. The MTD devices are not probed at this point and therefore it fails e.g. with this message:

=> mtdparts
Device spi-nand0 not found!

IIRC, we decided that mtdparts should not call mtd_probe_devices() to encourage people to stop using it.

Quoted 7 lines

Quoted 2 lines

I see. But I don't quite get how this missing call (and reslting error message) would encourage people to stop using it.

You're right, this message does not encourage people to stop using mtdparts on existing setups (mtdparts should work just fine on any MTD devices except SPI NANDs) but it does discourage them from using it on spi-nand devices since it returns an error.

IMHO, that's more confusing than discouraging.

Quoted 17 lines

Quoted 17 lines

Quoted 8 lines

Quoted 4 lines

This patch adds a call to mtd_probe_devices() to mtdparts_init() to solve this issue. This also fixes a problem when calling "ubi part" as first flash storage related command.

Hm, this one is unexpected. Miquel, any idea why this happens. Do we need to enable a specific option if we want mtd_probe_devices() to be called in the ubi part path?

Please note that "ubi part part-foo" does still work. It only prints this error message before attaching the MTD partition. The error is printed because of this call-chain:

ubi_part()
-> ubi_detach()

       -> mtdparts_init()

Quoted 8 lines

Quoted 2 lines

So again, mtdparts_init() is called without the MTD devices being probed.

I guess we forgot to remove this mtdparts_init() call from the detach path. I think it's no longer needed since we now call mtd_probe_devices() in ubi_part(), and mtd_probe_devices() will take care of creating MTD partitions based on the mtdparts= and mtdids= variables.

A quick test reveals that this removal does not remove the error message. Instead the command does not work anymore at all:

=> ubi part nand
Partition nand not found!

Quoted 8 lines

Before (and without my patch) its this:

=> ubi part nand
Device spi-nand0 not found!
Error initializing mtdparts!
ubi0: attaching mtd2
ubi0: scanning is finished
ubi0: attached mtd2 (name "nand", size 128 MiB)

Quoted 3 lines

I think I found what's missing in mtd_probe_devices(): we don't use the default mtdparts and mtdids when those env vars are NULL (see what's done in mtdparts_init() to handle this case [1]).

Can you try with the following diff applied?

--->8---

cmd/ubi.c +0 -5

index 767a4a453640..2b74a9814463 100644
@@ -417,11 +417,6 @@ static int ubi_dev_scan(struct mtd_info *info, const char *vid_header_offset)
 
  int ubi_detach(void)
  {
-       if (mtdparts_init() != 0) {
-               printf("Error initializing mtdparts!\n");
-               return 1;
-       }
-
  #ifdef CONFIG_CMD_UBIFS
         /*
          * Automatically unmount UBIFS partition when user

drivers/mtd/mtd_uboot.c +58 -0

index 7d7a11c990d6..1d0a505754f2 100644
@@ -92,12 +92,70 @@ static void mtd_probe_uclass_mtd_devs(void) { }
  #endif
 
  #if defined(CONFIG_MTD_PARTITIONS)
+extern void board_mtdparts_default(const char **mtdids,
+                                  const char **mtdparts);
+
+static const char *get_mtdids(void)
+{
+       __maybe_unused const char *mtdparts = NULL;
+       const char *mtdids = env_get("mtdids");
+
+       if (mtdids)
+               return mtdids;
+
+#if defined(CONFIG_SYS_MTDPARTS_RUNTIME)
+       board_mtdparts_default(&mtdids, &mtdparts);
+#elif defined(MTDIDS_DEFAULT)
+       mtdids = MTDIDS_DEFAULT;
+#elif defined(CONFIG_MTDIDS_DEFAULT)
+       mtdids = CONFIG_MTDIDS_DEFAULT;
+#endif
+
+       if (mtdids)
+               env_set("mtdids", mtdids);
+
+       return mtdids;
+}
+
+#define MTDPARTS_MAXLEN         512
+
+static const char *get_mtdparts(void)
+{
+       __maybe_unused const char *mtdids = NULL;
+       static char tmp_parts[MTDPARTS_MAXLEN];
+       static bool use_defaults = true;
+       const char *mtdparts = NULL;
+
+       if (gd->flags & GD_FLG_ENV_READY)
+               mtdparts = env_get("mtdparts");
+       else if (env_get_f("mtdparts", tmp_parts, sizeof(tmp_parts) != -1))
+               mtdparts = tmp_parts;
+
+       if (mtdparts || !use_defaults)
+               return mtdparts;
+
+#if defined(CONFIG_SYS_MTDPARTS_RUNTIME)
+       board_mtdparts_default(&mtdids, &mtdparts);
+#elif defined(MTDPARTS_DEFAULT)
+       mtdparts = MTDPARTS_DEFAULT;
+#elif defined(CONFIG_MTDPARTS_DEFAULT)
+       mtdparts = CONFIG_MTDPARTS_DEFAULT;
+#endif
+
+       if (mtdparts)
+               env_set("mtdparts", mtdparts);
+
+       use_defaults = false;
+
+       return mtdparts;
+}
+
  int mtd_probe_devices(void)

Quoted 63 lines · On Tue, 30 Oct 2018 11:59:13 +0100 Stefan Roese <[email protected]> wrote:

Quoted 19 lines · Boris Brezillon

Quoted 16 lines · On Tue, 30 Oct 2018 11:13:37 +0100 Stefan Roese <[email protected]> wrote:

Hi Boris,

Quoted 12 lines · Boris Brezillon

Quoted 6 lines · On Tue, 30 Oct 2018 10:51:51 +0100 Stefan Roese <[email protected]> wrote:

Calling "mtdparts" currently fails when its called before any other mtd command (or ubi command) has been called. The MTD devices are not probed at this point and therefore it fails e.g. with this message:

=> mtdparts
Device spi-nand0 not found!

IIRC, we decided that mtdparts should not call mtd_probe_devices() to encourage people to stop using it.

Quoted 7 lines

Quoted 2 lines

I see. But I don't quite get how this missing call (and reslting error message) would encourage people to stop using it.

You're right, this message does not encourage people to stop using mtdparts on existing setups (mtdparts should work just fine on any MTD devices except SPI NANDs) but it does discourage them from using it on spi-nand devices since it returns an error.

IMHO, that's more confusing than discouraging.

Quoted 17 lines

Quoted 17 lines

Quoted 8 lines

Quoted 4 lines

This patch adds a call to mtd_probe_devices() to mtdparts_init() to solve this issue. This also fixes a problem when calling "ubi part" as first flash storage related command.

Hm, this one is unexpected. Miquel, any idea why this happens. Do we need to enable a specific option if we want mtd_probe_devices() to be called in the ubi part path?

Please note that "ubi part part-foo" does still work. It only prints this error message before attaching the MTD partition. The error is printed because of this call-chain:

ubi_part()
-> ubi_detach()

      -> mtdparts_init()    

Quoted 8 lines

Quoted 2 lines

So again, mtdparts_init() is called without the MTD devices being probed.

I guess we forgot to remove this mtdparts_init() call from the detach path. I think it's no longer needed since we now call mtd_probe_devices() in ubi_part(), and mtd_probe_devices() will take care of creating MTD partitions based on the mtdparts= and mtdids= variables.

A quick test reveals that this removal does not remove the error message. Instead the command does not work anymore at all:

=> ubi part nand
Partition nand not found!

Quoted 8 lines

Before (and without my patch) its this:

=> ubi part nand
Device spi-nand0 not found!
Error initializing mtdparts!
ubi0: attaching mtd2
ubi0: scanning is finished
ubi0: attached mtd2 (name "nand", size 128 MiB)

I think I found what's missing in mtd_probe_devices(): we don't use the default mtdparts and mtdids when those env vars are NULL (see what's done in mtdparts_init() to handle this case [1]).

[1]https://elixir.bootlin.com/u-boot/v2018.11-rc3/source/cmd/mtdparts.c#L1763

Hi Boris,

Boris Brezillon <[email protected]> wrote on Tue, 30 Oct 2018 23:02:50 +0100:

Quoted 79 lines

Quoted 63 lines · On Tue, 30 Oct 2018 11:59:13 +0100 Stefan Roese <[email protected]> wrote:

Quoted 19 lines · Boris Brezillon

Quoted 16 lines · On Tue, 30 Oct 2018 11:13:37 +0100 Stefan Roese <[email protected]> wrote:

Hi Boris,

Quoted 12 lines · Boris Brezillon

Quoted 6 lines · On Tue, 30 Oct 2018 10:51:51 +0100 Stefan Roese <[email protected]> wrote:

Calling "mtdparts" currently fails when its called before any other mtd command (or ubi command) has been called. The MTD devices are not probed at this point and therefore it fails e.g. with this message:

=> mtdparts
Device spi-nand0 not found!

IIRC, we decided that mtdparts should not call mtd_probe_devices() to encourage people to stop using it.

Quoted 7 lines

Quoted 2 lines

I see. But I don't quite get how this missing call (and reslting error message) would encourage people to stop using it.

You're right, this message does not encourage people to stop using mtdparts on existing setups (mtdparts should work just fine on any MTD devices except SPI NANDs) but it does discourage them from using it on spi-nand devices since it returns an error.

IMHO, that's more confusing than discouraging.

Quoted 17 lines

Quoted 17 lines

Quoted 8 lines

Quoted 4 lines

This patch adds a call to mtd_probe_devices() to mtdparts_init() to solve this issue. This also fixes a problem when calling "ubi part" as first flash storage related command.

Hm, this one is unexpected. Miquel, any idea why this happens. Do we need to enable a specific option if we want mtd_probe_devices() to be called in the ubi part path?

Please note that "ubi part part-foo" does still work. It only prints this error message before attaching the MTD partition. The error is printed because of this call-chain:

ubi_part()
-> ubi_detach()

      -> mtdparts_init()      

Quoted 8 lines

Quoted 2 lines

So again, mtdparts_init() is called without the MTD devices being probed.

I guess we forgot to remove this mtdparts_init() call from the detach path. I think it's no longer needed since we now call mtd_probe_devices() in ubi_part(), and mtd_probe_devices() will take care of creating MTD partitions based on the mtdparts= and mtdids= variables.

A quick test reveals that this removal does not remove the error message. Instead the command does not work anymore at all:

=> ubi part nand
Partition nand not found!

Quoted 8 lines

Before (and without my patch) its this:

=> ubi part nand
Device spi-nand0 not found!
Error initializing mtdparts!
ubi0: attaching mtd2
ubi0: scanning is finished
ubi0: attached mtd2 (name "nand", size 128 MiB)

I think I found what's missing in mtd_probe_devices(): we don't use the default mtdparts and mtdids when those env vars are NULL (see what's done in mtdparts_init() to handle this case [1]).

Quoted 1 line

[1]https://elixir.bootlin.com/u-boot/v2018.11-rc3/source/cmd/mtdparts.c#L1763

Isn't the right solution to always define these env variables when they are needed? Defining such default behavior with a Kconfig entry is, from my opinion, a lot of noise for such an useless feature...