Re:RE: [PATCH] pinctrl: mcp23s08: reject devices without match data

[jiale yao]

Hi Biju,

At 2026-09-26 18:07:14, "Biju Das" <biju.das.jz@xxxxxxxxxxxxxx> wrote:
>Hi,
>
>> -----Original Message-----
>> From: Jiale Yao <yaojiale02@xxxxxxx>
>> Sent: 25 September 2026 14:38
>> Subject: [PATCH] pinctrl: mcp23s08: reject devices without match data
>> 
>> A device bound through driver_override need not match an entry in the driver tables. In that case
>> spi_get_device_match_data() returns NULL, but mcp23s08_probe() later passes the result to the regmap
>> setup and dereferences it while setting up each device.
>
>I believe this is an invalid use case as the user trying driver_override
>and the probe returns error. Am I missing anything here?

Yes, my commit message was not clear enough. This patch is intended to fix
a regression introduced by commit 2e44555b05c0, rather than to make an
unmatched device probe successfully through driver_override.

Before that commit, missing match data effectively resulted in type 0,
which fell through to the default switch case and returned -EINVAL.
Commit 2e44555b05c0 replaced the type value with an info pointer, but the
SPI path missed the corresponding NULL check before dereferencing
info->type. The I2C path preserved the previous error handling with an
explicit NULL check after the same conversion.

Consequently, an unmatched device bound through driver_override used to
fail cleanly. It can now cause a NULL pointer dereference when a valid
spi-present-mask property is present. This patch restores the previous
failure behavior.

>
>Can you please prepare a patch that makes the driver probe success by using driver_override
>Feature? Also please share some logs to see how it works in real device
>
>Cheers,
>Biju
>
>> 
>> Reject devices without match data before reading device properties.
>> 
>> Fixes: 2e44555b05c0 ("pinctrl: mcp23s08: Simplify probe()/mcp23s08_spi_regmap_init()")
>> Signed-off-by: Jiale Yao <yaojiale02@xxxxxxx>
>> ---
>>  drivers/pinctrl/pinctrl-mcp23s08_spi.c | 2 ++
>>  1 file changed, 2 insertions(+)
>> 
>> diff --git a/drivers/pinctrl/pinctrl-mcp23s08_spi.c b/drivers/pinctrl/pinctrl-mcp23s08_spi.c
>> index bacebcff67ef..926034fcd512 100644
>> --- a/drivers/pinctrl/pinctrl-mcp23s08_spi.c
>> +++ b/drivers/pinctrl/pinctrl-mcp23s08_spi.c
>> @@ -146,6 +146,8 @@ static int mcp23s08_probe(struct spi_device *spi)
>>  	u8 v;
>> 
>>  	info = spi_get_device_match_data(spi);
>> +	if (!info)
>> +		return -ENODATA;
>> 
>>  	ret = device_property_read_u8(dev, "microchip,spi-present-mask", &v);
>>  	if (ret) {
>> --
>> 2.34.1

Cheers,
Jiale