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Date:   Thu, 05 Jan 2023 13:51:53 +0100
From:   Michael Walle <michael@walle.cc>
To:     Alexander Stein <alexander.stein@ew.tq-group.com>
Cc:     Miquel Raynal <miquel.raynal@bootlin.com>,
        Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Rob Herring <robh+dt@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
        Dan Carpenter <error27@gmail.com>
Subject: Re: [PATCH v5 00/21] nvmem: core: introduce NVMEM layouts
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References: <20221206200740.3567551-1-michael@walle.cc>
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 <5906091.UjTJXf6HLC@steina-w>
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Hi,

Am 2023-01-05 13:21, schrieb Alexander Stein:
> Am Donnerstag, 5. Januar 2023, 13:11:37 CET schrieb Michael Walle:
>> 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.

Ahh I see. You mean ENOENT instead of ENODEV, right?

>> > 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.

Thanks, could you try the following patch:

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 1b61c8bf0de4..1085abfcd9b1 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -1336,8 +1336,11 @@ struct nvmem_cell *of_nvmem_cell_get(struct 
device_node *np, const char *id)
         int ret;

         /* if cell name exists, find index to the name */
-       if (id)
+       if (id) {
                 index = of_property_match_string(np, "nvmem-cell-names", 
id);
+               if (index < 0)
+                       return ERR_PTR(-ENOENT);
+       }

         ret = of_parse_phandle_with_optional_args(np, "nvmem-cells",
                                                   "#nvmem-cell-cells",

Before patch 6/21, the -EINVAL was passed as index to of_parse_phandle()
which then returned NULL, which caused the nvmem core to return ENOENT.
I have a vague memory, that I made sure, that
of_parse_phandle_with_optional_args() will also propagate the
wrong index to its return code. But now, it won't be converted
to ENOENT.

-michael