Re: [PATCH v12 5/7] nvmem: core: Rework layouts to become regular devices

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hi Srinivas,

> > you don't have access to your modules. And anyway it's probably a bad
> > idea to allow endless probe deferrals on your main storage device.
> > 
> > If the cells are not available at that time, it's not a huge deal? The
> > consumers will have to wait a bit more (or take any other action, this
> > is device dependent).  
> 
> In this case the nvmem consumers will get an -ENOENT error, which is very confusing TBH.

Maybe we can solve that situation like that (based on my current
series):

--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -1448,7 +1448,10 @@ struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
        of_node_put(cell_np);
        if (!cell_entry) {
                __nvmem_device_put(nvmem);
-               return ERR_PTR(-ENOENT);
+               if (nvmem->layout)
+                       return ERR_PTR(-EAGAIN);
+               else
+                       return ERR_PTR(-ENOENT);
        }
 
        cell = nvmem_create_cell(cell_entry, id, cell_index);


So this way when a (DT) consumer requests a cell:
- the cell is ready and it gets it
- the cell is not ready and...
   - the cell comes from a layout -> we return EAGAIN, which
     means the cell is not yet ready and this must be retried later
     (the caller may return EPROBE_DEFER in this case).
   - the cell is simply missing/not existing/not available, this is a
     real error.

What do you think?

Thanks,
Miquèl