On Sun, 15 Feb 2026 22:06:28 +0200 Erikas Bitovtas <[email protected]> wrote:
> On 2/15/26 9:31 PM, Jonathan Cameron wrote: > > On Sun, 15 Feb 2026 19:28:56 +0200 > > Erikas Bitovtas <[email protected]> wrote: > > > >> On 2/14/26 8:09 PM, Jonathan Cameron wrote: > >>>> --- > >>>> drivers/iio/light/vcnl4000.c | 40 > >>>> ++++++++++++++++++++++++++++++++++++++++ > >>>> 1 file changed, 40 insertions(+) > >>>> > >>>> diff --git a/drivers/iio/light/vcnl4000.c b/drivers/iio/light/vcnl4000.c > >>>> index a36c23813679..1f8f4e4586f4 100644 > >>>> --- a/drivers/iio/light/vcnl4000.c > >>>> +++ b/drivers/iio/light/vcnl4000.c > >>>> @@ -185,6 +185,7 @@ static const int vcnl4040_ps_oversampling_ratio[] = > >>>> {1, 2, 4, 8}; > >>>> #define VCNL4000_SLEEP_DELAY_MS 2000 /* before we enter > >>>> pm_runtime_suspend */ > >>>> > >>>> enum vcnl4000_device_ids { > >>>> + CM36672P, > >>>> VCNL4000, > >>>> VCNL4010, > >>>> VCNL4040, > >>>> @@ -235,6 +236,8 @@ struct vcnl4000_chip_spec { > >>>> }; > >>>> > >>>> static const struct i2c_device_id vcnl4000_id[] = { > >>>> + { "cm36672p", CM36672P }, > >>>> + { "cm36686", VCNL4040 }, > >>>> { "vcnl4000", VCNL4000 }, > >>>> { "vcnl4010", VCNL4010 }, > >>>> { "vcnl4020", VCNL4010 }, > >>>> @@ -1842,6 +1845,22 @@ static const struct iio_chan_spec > >>>> vcnl4040_channels[] = { > >>>> } > >>>> }; > >>> > >>> ... > >>> > >>>> [VCNL4000] = { > >>>> .prod = "VCNL4000", > >>>> .init = vcnl4000_init, > >>>> @@ -2033,6 +2065,14 @@ static int vcnl4000_probe(struct i2c_client > >>>> *client) > >>>> } > >>>> > >>>> static const struct of_device_id vcnl_4000_of_match[] = { > >>>> + { > >>>> + .compatible = "capella,cm36672p", > >>>> + .data = (void *)CM36672P, > >>>> + }, > >>>> + { > >>>> + .compatible = "capella,cm36686", > >>>> + .data = (void *)VCNL4040, > >>> > >>> Is this necessary? I 'think' if you drop it we'll match instead > >>> on the vcnl4040 fallback and then the access to the data will be > >>> through the stripped name only bit of the compatible (first entry, not > >>> the fallback so cm36686 in this case). So you do need the cm36686 > >>> entry in the i2c_device_id table above. Probably better to keep > >>> this here to avoid having to reason this out - but perhaps a > >>> comment to that affect would be useful (assuming you verify my > >>> reasoning). > >>> > >> After I removed the entry for "capella,cm36686", I received the "Unable > >> to handle kernel NULL pointer dereference" error in dmesg. And at least > >> stk3310 driver includes a compatible entry both for the device (stk3013) > >> and for the fallback (stk3310). So my assumption is that this entry is > >> needed. > >> I could include a comment explaining that cm36686 is fully compatible > >> with vcnl4040, however, if that is necessary. > > > > Thanks for checking. > > > > What did you get as the backtrace? I'm hoping it'll explain what I'm > > misunderstanding! The hacks around using the wrong table for compatible > > matches have tripped me up before. > > > > Jonathan > > > > I am attaching a link to the dmesg. There were quite a lot of lines in > the stack trace and I am not sure what is the right way to post logs in > the mailing list. > > https://pastebin.com/QgeTdNEP Thanks. only relevant bit is probably: [ 15.566076] vcnl4000_probe+0x54/0x288 [vcnl4000] (P) [ 15.566102] i2c_device_probe+0x2b0/0x358 [ 15.566121] really_probe+0x154/0x448 My guess is my understanding of i2c_client_get_device_id() is wrong and that is returning NULL. That can only happen if client->name is not a match for anything the i2_device_id table. If you have a chance, can you dump what client->name is in this case? I thought it ended up as cm36686 (stripped first entry in compatible) but seems I'm probably wrong on that :( The path I thought worked was via info->type (which gets copied to client->name) set via of_alias_from_compatible() here. https://elixir.bootlin.com/linux/v6.19-rc4/source/drivers/i2c/i2c-core-of.c#L30 Which should just return the first compatible without that vendor prefix. Meh, this doesn't really matter anyway as once we refactor to actually use the data in the of_device_id table, we will need the entry and in the meantime it's sort of documentation. J >
