Re: [PATCH v5 00/21] nvmem: core: introduce NVMEM layouts

Alexander Stein
2023-01-05T22:22:32Z

Hi Michael,

Am Donnerstag, 5. Januar 2023, 13:11:37 CET schrieb Michael Walle:
> Hi Alexander,
>
> thanks for debugging. I'm not yet sure what is going wrong, so
> I have some more questions below.
>
> >> This causes the following errors on existing boards (imx8mq-tqma8mq-
> >> mba8mx.dtb):
> >> root@tqma8-common:~# uname -r
> >> 6.2.0-rc2-next-20230105
> >>
> >> > OF: /soc@0: could not get #nvmem-cell-cells for /soc@0/bus@30000000/
> >>
> >> efuse@30350000/soc-uid@4
> >>
> >> > OF: /soc@0/bus@30800000/ethernet@30be0000: could not get
> >> > #nvmem-cell-cells
> >>
> >> for /soc@0/bus@30000000/efuse@30350000/mac-address@90
> >>
> >> These are caused because '#nvmem-cell-cells = <0>;' is not explicitly
> >> set in
> >> DT.
> >>
> >> > TI DP83867 30be0000.ethernet-1:0e: error -EINVAL: failed to get nvmem
> >> > cell
> >>
> >> io_impedance_ctrl
> >>
> >> > TI DP83867: probe of 30be0000.ethernet-1:0e failed with error -22
> >>
> >> These are caused because of_nvmem_cell_get() now returns -EINVAL
> >> instead of -
> >> ENODEV if the requested nvmem cell is not available.
>
> What do you mean with not available? Not yet available because of probe
> order?

Ah, I was talking about there is no nvmem cell being used in my PHY node, e.g.
no 'nvmem-cells' nor 'nvmem-cell-names' (set to 'io_impedance_ctrl'). That's
why of_property_match_string returns -EINVAL.

> > Should we just assume #nvmem-cell-cells = <0> by default? I guess it's
> > a safe assumption.
>
> Actually, that's what patch 2/21 is for.
>
> Alexander, did you verify that the EINVAL is returned by
> of_parse_phandle_with_optional_args()?

Yep.

--8<--
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 1b61c8bf0de4..f2a85a31d039 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -1339,9 +1339,11 @@ struct nvmem_cell *of_nvmem_cell_get(struct device_node
*np, const char *id)
if (id)
index = of_property_match_string(np, "nvmem-cell-names", id);

+ pr_info("%s: index: %d\n", __func__, index);
ret = of_parse_phandle_with_optional_args(np, "nvmem-cells",
"#nvmem-cell-cells",
index, &cell_spec);
+ pr_info("%s: of_parse_phandle_with_optional_args: %d\n", __func__,
ret);
if (ret)
return ERR_PTR(ret);
--8<--

Results in:
> [ 1.861896] of_nvmem_cell_get: index: -22
> [ 1.865934] of_nvmem_cell_get: of_parse_phandle_with_optional_args: -22
> [ 1.872595] TI DP83867 30be0000.ethernet-1:0e: error -EINVAL: failed to
get nvmem cell io_impedance_ctrl
> [ 2.402575] TI DP83867: probe of 30be0000.ethernet-1:0e failed with error
-22

So, the index is wrong in the first place, but this was no problem until now.

Best regards,
Alexander