Re: [alsa-devel] [RFC PATCH 01/40] soundwire: add debugfs support

Pierre-Louis Bossart
2019-07-26T13:53:15Z

On 7/25/19 5:15 PM, Guennadi Liakhovetski wrote:
> Hi Pierre,
>
> A couple of nitpicks:

Thanks for the feedback!

>> create mode 100644 drivers/soundwire/debugfs.c
>
> [snip]
>
>> diff --git a/drivers/soundwire/bus.h b/drivers/soundwire/bus.h
>> index 3048ca153f22..06ac4adb0074 100644
>> --- a/drivers/soundwire/bus.h
>> +++ b/drivers/soundwire/bus.h
>> @@ -18,6 +18,30 @@ static inline int sdw_acpi_find_slaves(struct sdw_bus *bus)
>> void sdw_extract_slave_id(struct sdw_bus *bus,
>> u64 addr, struct sdw_slave_id *id);
>>
>> +#ifdef CONFIG_DEBUG_FS
>> +struct dentry *sdw_bus_debugfs_init(struct sdw_bus *bus);
>> +void sdw_bus_debugfs_exit(struct dentry *d);
>> +struct dentry *sdw_slave_debugfs_init(struct sdw_slave *slave);
>> +void sdw_slave_debugfs_exit(struct dentry *d);
>> +void sdw_debugfs_init(void);
>> +void sdw_debugfs_exit(void);
>> +#else
>> +struct dentry *sdw_bus_debugfs_init(struct sdw_bus *bus)
>> +{ return NULL; }
>
> static?
>
>> +
>> +void sdw_bus_debugfs_exit(struct dentry *d) {}
>> +
>> +struct dentry *sdw_slave_debugfs_init(struct sdw_slave *slave)
>> +{ return NULL; }
>> +
>> +void sdw_slave_debugfs_exit(struct dentry *d) {}
>> +
>> +void sdw_debugfs_init(void) {}
>> +
>> +void sdw_debugfs_exit(void) {}
>
> Same for all the above. You could also declare them inline, but I really hope
> the compiler will be smart enough to do that itself.

yes, I'll add static inline for all this.

>> +struct dentry *sdw_bus_debugfs_init(struct sdw_bus *bus)
>> +{
>> + struct dentry *d;
>
> I would remove the above
>
>> + char name[16];
>> +
>> + if (!sdw_debugfs_root)
>> + return NULL;
>> +
>> + /* create the debugfs master-N */
>> + snprintf(name, sizeof(name), "master-%d", bus->link_id);
>> + d = debugfs_create_dir(name, sdw_debugfs_root);
>> +
>> + return d;
>
> And just do
>
> + return debugfs_create_dir(name, sdw_debugfs_root);

yep, will do.

>> +static ssize_t sdw_sprintf(struct sdw_slave *slave,
>> + char *buf, size_t pos, unsigned int reg)
>> +{
>> + int value;
>> +
>> + value = sdw_read(slave, reg);
>
> I personally would join the two lines above, but that's just a personal
> preference.

I prefer splitting variables and code, I just can't mentally split the two.

>
>> +
>> + if (value < 0)
>> + return scnprintf(buf + pos, RD_BUF - pos, "%3x\tXX\n", reg);
>> + else
>
> I think it's advised to not use an else in such cases.
>
> Thanks
> Guennadi
>
>> + return scnprintf(buf + pos, RD_BUF - pos,
>> + "%3x\t%2x\n", reg, value);
>> +}

The intent was to provide a visual cue that the register is not
implemented, which is quite useful. Not all registers are mandatory and
not all vendors document the entire set of registers, so it's a good way
to figure things out. The value is not used for any functional purpose,
it's just a register dump for the integrator to look at. I'll add a note
to explain the idea.