Re: [PATCH 2/2] mtd: spi-nor: add initial sysfs support

[Vignesh Raghavendra]

On 4/6/21 2:17 PM, Michael Walle wrote:
> Hi,
> 
> Am 2021-04-06 09:56, schrieb Vignesh Raghavendra:
>> Hi,
>>
>> On 3/18/21 2:54 PM, Michael Walle wrote:
>>> Add support to show the name and JEDEC identifier as well as to dump the
>>> SFDP table. Not all flashes list their SFDP table contents in their
>>> datasheet. So having that is useful. It might also be helpful in bug
>>> reports from users.
>>>
>>
>> Sorry for the delay..
>>
>> There is already debugfs support for dumping JEDEC ID [1]. Any reason to
>> add sysfs entry as well?
> 
> This is per mtd while the sfdp is per flash device. IMHO both should
> be at the same place.
> 
>> That brings up another question. Since SFDP dumps are more of a debug
>> aid, should this be a debugfs entry rather than sysfs entry?
> 
> And you're not the first one asking that. My argument was that the
> debugfs might not be available just when you need it. A developer
> could easily rebuild a kernel, but imagine some user with a COTS
> distro and some problems, then it is not that easy anymore. But
> thats your call to make.
> 
>> Note that sysfs entries are userspace ABIs just like syscalls and thus
>> need to be documented in Documentation/ABI/testing/ or
>> Documentation/ABI/stable. Thus need to be carefully designed compared to
>> debugfs which are much more flexible.
> 
> Ok. But I don't see a problem adding these read-only files
>  /sfdp
>  /name
>  /jedec-id
> 

Hmm, ok. but do add documentation please.

Regards
Vignesh