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

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Message-ID: <5906091.UjTJXf6HLC@steina-w>
Date:   Thu, 05 Jan 2023 13:21:37 +0100
From:   Alexander Stein <alexander.stein@...tq-group.com>
To:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Michael Walle <michael@...le.cc>
Cc:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Jonathan Corbet <corbet@....net>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        Dan Carpenter <error27@...il.com>
Subject: Re: [PATCH v5 00/21] nvmem: core: introduce NVMEM layouts

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@...a8-common:~# uname -r
> >> 6.2.0-rc2-next-20230105
> >> 
> >> > OF: /soc@0: could not get #nvmem-cell-cells for /soc@...us@...00000/
> >> 
> >> efuse@...50000/soc-uid@4
> >> 
> >> > OF: /soc@...us@...00000/ethernet@...e0000: could not get
> >> > #nvmem-cell-cells
> >> 
> >> for /soc@...us@...00000/efuse@...50000/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