target/linux/generic/backport-6.1/811-v6.4-0003-nvmem-core-handle-the-absence-of-expected-layouts.patch

   1 From 6468a6f45148fb5e95c86b4efebf63f9abcd2137 Mon Sep 17 00:00:00 2001
   2 From: Miquel Raynal <miquel.raynal@bootlin.com>
   3 Date: Tue, 4 Apr 2023 18:21:22 +0100
   4 Subject: [PATCH] nvmem: core: handle the absence of expected layouts
   5
   6 Make nvmem_layout_get() return -EPROBE_DEFER while the expected layout
   7 is not available. This condition cannot be triggered today as nvmem
   8 layout drivers are initialed as part of an early init call, but soon
   9 these drivers will be converted into modules and be initialized with a
  10 standard priority, so the unavailability of the drivers might become a
  11 reality that must be taken care of.
  12
  13 Let's anticipate this by telling the caller the layout might not yet be
  14 available. A probe deferral is requested in this case.
  15
  16 Please note this does not affect any nvmem device not using layouts,
  17 because an early check against the "nvmem-layout" container presence
  18 will return NULL in this case.
  19
  20 Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
  21 Tested-by: Michael Walle <michael@walle.cc>
  22 Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
  23 Link: https://lore.kernel.org/r/20230404172148.82422-15-srinivas.kandagatla@linaro.org
  24 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  25 ---
  26  drivers/nvmem/core.c | 10 +++++++++-
  27  1 file changed, 9 insertions(+), 1 deletion(-)
  28
  29 --- a/drivers/nvmem/core.c
  30 +++ b/drivers/nvmem/core.c
  31 @@ -755,7 +755,7 @@ EXPORT_SYMBOL_GPL(nvmem_layout_unregiste
  32  static struct nvmem_layout *nvmem_layout_get(struct nvmem_device *nvmem)
  33  {
  34         struct device_node *layout_np, *np = nvmem->dev.of_node;
  35 -       struct nvmem_layout *l, *layout = NULL;
  36 +       struct nvmem_layout *l, *layout = ERR_PTR(-EPROBE_DEFER);
  37
  38         layout_np = of_get_child_by_name(np, "nvmem-layout");
  39         if (!layout_np)
  40 @@ -938,6 +938,13 @@ struct nvmem_device *nvmem_register(cons
  41          * pointer will be NULL and nvmem_layout_put() will be a noop.
  42          */
  43         nvmem->layout = config->layout ?: nvmem_layout_get(nvmem);
  44 +       if (IS_ERR(nvmem->layout)) {
  45 +               rval = PTR_ERR(nvmem->layout);
  46 +               nvmem->layout = NULL;
  47 +
  48 +               if (rval == -EPROBE_DEFER)
  49 +                       goto err_teardown_compat;
  50 +       }
  51
  52         if (config->cells) {
  53                 rval = nvmem_add_cells(nvmem, config->cells, config->ncells);
  54 @@ -970,6 +977,7 @@ struct nvmem_device *nvmem_register(cons
  55  err_remove_cells:
  56         nvmem_device_remove_all_cells(nvmem);
  57         nvmem_layout_put(nvmem->layout);
  58 +err_teardown_compat:
  59         if (config->compat)
  60                 nvmem_sysfs_remove_compat(nvmem, config);
  61  err_put_device: