target/linux/generic/pending-6.1/401-mtd-don-t-register-NVMEM-devices-for-partitions-with.patch

   1 From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
   2 Date: Tue, 31 Oct 2023 15:51:01 +0100
   3 Subject: [PATCH] mtd: don't register NVMEM devices for partitions with custom
   4  drivers
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 This fixes issue exposed by upstream commit f4cf4e5db331 ("Revert
  10 "nvmem: add new config option"").
  11
  12 Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
  13 ---
  14  drivers/mtd/mtdcore.c | 23 +++++++++++++++++++++++
  15  1 file changed, 23 insertions(+)
  16
  17 --- a/drivers/mtd/mtdcore.c
  18 +++ b/drivers/mtd/mtdcore.c
  19 @@ -519,6 +519,29 @@ static int mtd_nvmem_add(struct mtd_info
  20         struct device_node *node = mtd_get_of_node(mtd);
  21         struct nvmem_config config = {};
  22
  23 +       /*
  24 +        * Do NOT register NVMEM device for any partition that is meant to be
  25 +        * handled by a U-Boot env driver. That would result in associating two
  26 +        * different NVMEM devices with the same OF node.
  27 +        *
  28 +        * An example of unwanted behaviour of above (forwardtrace):
  29 +        * of_get_mac_addr_nvmem()
  30 +        * of_nvmem_cell_get()
  31 +        * __nvmem_device_get()
  32 +        *
  33 +        * We can't have __nvmem_device_get() return "mtdX" NVMEM device instead
  34 +        * of U-Boot env NVMEM device. That would result in failing to find
  35 +        * NVMEM cell.
  36 +        *
  37 +        * This issue seems to affect U-Boot env case only and will go away with
  38 +        * switch to NVMEM layouts.
  39 +        */
  40 +       if (of_device_is_compatible(node, "u-boot,env") ||
  41 +           of_device_is_compatible(node, "u-boot,env-redundant-bool") ||
  42 +           of_device_is_compatible(node, "u-boot,env-redundant-count") ||
  43 +           of_device_is_compatible(node, "brcm,env"))
  44 +               return 0;
  45 +
  46         config.id = -1;
  47         config.dev = &mtd->dev;
  48         config.name = dev_name(&mtd->dev);