Re: [PATCH] soc: qcom: cmd-db: fix minor version decoding in debugfs output

[ALOK TIWARI <alok.a.tiwari@oracle.com>]

On 3/30/2026 11:05 AM, Sneh Mankad wrote:
>> cmd-db encodes the version as major in the high byte and minor in the low
>> byte. cmd_db_debugfs_dump() prints the full 16 bit value as the minor
>> version, resulting in incorrect output.
>>
>> Extract minor from the low byte using (version & 0xff).
>>
>> Signed-off-by: Alok Tiwari <alok.a.tiwari@oracle.com>
> There should be a "fixes:" tag added since this is a fix.
>> ---
>>   drivers/soc/qcom/cmd-db.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/soc/qcom/cmd-db.c b/drivers/soc/qcom/cmd-db.c
>> index 84a75d8c4b70..eed7013c7676 100644
>> --- a/drivers/soc/qcom/cmd-db.c
>> +++ b/drivers/soc/qcom/cmd-db.c
>> @@ -301,7 +301,7 @@ static int cmd_db_debugfs_dump(struct seq_file 
>> *seq, void *p)
>>           version = le16_to_cpu(rsc->version);
>>           major = version >> 8;
>> -        minor = version;
>> +        minor = version & 0xff;
> 
> Minor is already a u8 type, so assigning a u16 type version to u8 type 
> will automatically truncate the higher 8 bits.
> 
> Its the same reason why version is right shifted by 8 before being 
> assigned to major variable.
> 
> I do not think there would be any difference in output with or without 
> the change, do you have any example?


Thanks for pointing this out.

You are right that if minor is of type u8, assigning a u16 value will
implicitly truncate the upper 8 bits.

However, the intention of the change is to explicitly extract the minor
version from the lower byte, since the encoding defines the version as 
major in the high byte and minor in the low byte.

Using version & 0xff makes the extraction explicit and consistent with 
how major is derived using version >> 8. It improves readability and 
avoids relying on implicit truncation.

Since this change does not alter functionality and is mainly for clarity 
and consistency I believe a Fixes: tag may not be appropriate.
I can also drop “fix” from the subject to avoid confusion.

Thanks,
Alok